Re: [Cryptography] funding Tor development

2013-10-17 Thread Dave Howe
On 14/10/2013 14:36, Eugen Leitl wrote:
 Guys, in order to minimize Tor Project's dependance on
 federal funding and/or increase what they can do it
 would be great to have some additional funding ~10 kUSD/month.
I would say what is needed is not one source at $10K/month but 10K
sources at $1/month.

A single source of funding is *always* a single source of control.
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Re: [Cryptography] AES [was NSA and cryptanalysis]

2013-09-17 Thread Dave Howe
On 16/09/2013 23:39, Perry E. Metzger wrote:
 On Mon, 16 Sep 2013 11:54:13 -1000 Tim Newsham
 tim.news...@gmail.com wrote:
 - A backdoor that leaks cryptographic secrets

 consider for example applications using an intel chip with
 hardware-assist for AES. You're feeding your AES keys
 directly into the cpu. Any attacker controlling the cpu has
 direct access and doesn't have to do any fancy pattern matching
 to discover the keys. Now if that CPU had a way to export
 some or all of the bits through some channel that would also
 be passively observable, the attacker could pull off an offline
 passive attack.

 What about RNG output? What if some bits were redundantly
 encoded in some of the RNG output bits which where then
 used directly for tcp initial sequence numbers?

 Such a backdoor would be feasible.
 It might be feasible in theory (and see the Illinois Malicious
 Processor as an example) but I think it would be hard to pull off
 well -- too hard to account for changes in future code, too hard to
 avoid detection of what you've done.
Not sure this is true. If instead of leaking via the RNG, you leak via
the cryptographic libraries *and* the windows socket libraries, then
while there are probably two different teams involved, there is only one
manufacturer - Microsoft.

Ok that would exclude non-windows systems, which in this world of BYOD
means an increasing number of ios or android devices - but the odds of
one end or the other of any given exchange being a MS platform are
good.  Provided the cryptographic libraries are queried in a specific
manner for tcp sequence numbers (which can be enforced) the winsock team
never need know how those are generated, leaving just the cryptographic
library holding both the input and output.




 On the other hand, we know from the press reports that several
 hardware crypto accelerators have been either backdoored or
 exploited. In those, leaking key material to observers in things like
 IVs or choices of nonces might be quite feasible. Such devices are
 built to be tamper resistant so no one will even notice if you add
 features to try to conceal the extra functionality of the device.

 For the Intel chips, I suspect that if they've been gimmicked, it
 will be more subtle, like a skew in the RNG that could be explained
 away as a manufacturing or design error. That said, things like the
 IMP do give one pause. And *that* said, if you're willing to go as
 far as what the IMP does, you no longer need to simply try to leak
 information via the RNG or other crypto hardware, you can do far far
 worse.

 (For those not familiar with the Illinois Malicious Processor:
 https://www.usenix.org/legacy/event/leet08/tech/full_papers/king/king_html/
 )

 Perry

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Re: Source for Skype Trojan released

2009-09-08 Thread Dave Howe
Stephan Neuhaus wrote:
 
 On Aug 31, 2009, at 13:20, Jerry Leichter wrote:
 
 It can “...intercept all audio data coming and going to the Skype
 process.”
 
 Interesting, but is this a novel idea? As far as I can see, the process
 intercepts the audio before it reaches Skype and after it has left
 Skype. Isn't that the same as calling a keylogger a PGP Trojan?

Not really. more generically, you could call it a VoIP trojan or even
Audio monitoring trojan - presumably a more advanced version could
listen to the mic stream even when the VoIP application is not in use,
in order to obtain information.

However, in context, this was designed to be used for law enforcement to
bug a skype VoIP session, so the name reflects the design goal; yes,
it is a more generalized attack than that, but not in intent or
(presumed) usage.

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Re: X.509 certificate overview + status

2009-03-02 Thread Dave Howe
Travis wrote:
 Hello,
 
 Recently I set up certificates for my server's SSL, SMTP, IMAP, XMPP,
 and OpenVPN services.  Actually, I created my own CA for some of the
 certificates, and in other cases I used self-signed.  It took me
 substantially more time than I had anticipated, and I'm left with
 feelings of unease.

odd. the openssl installations I am familiar with came with example
config files that were perfectly functional, took me about ten minutes
to figure out what needed doing purely from the man pages and the
example config.

if ten minutes is too long, just go with xca
(http://sourceforge.net/projects/xca) which does it all in a nice,
pretty gui for you. A few distros (suse, for example) also have a gui
for certificate issuing in their central admin tool.

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Re: once more, with feeling.

2008-09-10 Thread Dave Howe
Darren J Moffat wrote:
 Warnings aren't enough in this context [ whey already exists ] the
 only thing that will work is stopping the page being seen - replacing
 it with a clearly worded explanation with *no* way to pass through
 and render the page (okay maybe with a debug build of the browser but
 not in the shipped product).

One thing that concerns me is that in the new release of firefox, there
appears to be NO way to get to a site that has a bad certificate (or
self signed certificate) other than overriding the warning permanently -
no ok let me see it, I have seen the warning and want to look just this
once that the remember mismatched domains plugin for 2.x gave you.

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Re: once more, with feeling.

2008-09-10 Thread Dave Howe
Paul Hoffman wrote:
 At 11:21 PM +0100 9/9/08, Dave Howe wrote:
 Darren J Moffat wrote:
  Warnings aren't enough in this context [ whey already exists ] the
  only thing that will work is stopping the page being seen - replacing
  it with a clearly worded explanation with *no* way to pass through
  and render the page (okay maybe with a debug build of the browser but
  not in the shipped product).

 One thing that concerns me is that in the new release of firefox, there
 appears to be NO way to get to a site that has a bad certificate (or
 self signed certificate) other than overriding the warning permanently -
 no ok let me see it, I have seen the warning and want to look just this
 once that the remember mismatched domains plugin for 2.x gave you.
 
 That may concern you, but I consider it a feature. Instead of teaching
 users to always click through the damn dialog boxes, FF3 says if you
 fell for it once, you're going to always fall for it so we won't teach
 you bad habits. There are arguments for either strategy.

True enough, but the clickthru bandits will just see a button that
reads to them make this error go away then next time will forget they
did it - and will take the fact that they went straight into the site to
mean the problem was fixed or simply not remember there ever was a
problem.

In the meantime, a choice I *used to have* is now taken from me, in the
interests of selling more EV certificates.

 Given that few or none of us on this list are actually trained interface
 experts, I'm sure we could debate this until Perry pulls the moderator
 switch again. The salient point is that people who have more stake in
 the game (Mozilla Inc.) have spent longer thinking about this than we
 give them credit for and come to the design decisions that they have.

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Re: Ransomware

2008-06-11 Thread Dave Howe

The Fungi wrote:

On Tue, Jun 10, 2008 at 11:41:56PM +0100, Dave Howe wrote:

The key size would imply PKI; that being true, then the ransom may
be  for a session key (specific per machine) rather than the
master key it  is unwrapped with.


Per the computerworld.com article:

   Kaspersky has the public key in hand ? it is included in the
   Trojan's code ? but not the associated private key necessary to
   unlock the encrypted files.

http://www.computerworld.com/action/article.do?command=viewArticleBasicarticleId=9094818

This would seem to imply they already verified the public key was
constant in the trojan and didn't differ between machines (or that
I'm giving Kaspersky's team too much credit with my assumptions).


Sure. however, if the virus (once infecting the machine) generated a 
random session key, symmetric-encrypted the files, then encrypted the 
session key with the public key as part of the ransom note then that 
would allow a single public key to be used to issue multiple ransom 
demands, without the unlocking of any one machine revealing the master 
key that could unlock all of them.


giving away your entire extortion capability to the first person to pay 
up doesn't seem sane, if you could as easily make each machine a unique 
proposition...


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Re: Ransomware

2008-06-10 Thread Dave Howe

Jim Youll wrote:

If there's just one key, then Kaspersky could get maximum press by
paying the ransom and publishing it. If there are many keys, then Kaspersky
still has reached its press-coverage quota, just not as dramatically.


The key size would imply PKI; that being true, then the ransom may be 
for a session key (specific per machine) rather than the master key it 
is unwrapped with.


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Re: Can we copy trust?

2008-06-03 Thread Dave Howe

Ben Laurie wrote:

Ed Gerck wrote:

Ben Laurie wrote:
But doesn't that prove the point? The trust that you consequently 
place in the web server because of the certificate _cannot_ be copied 
to another webserver. That other webserver has to go out and buy its 
own copy, with its own domain name it it.


A copy is something identical. So, in fact you can copy that server 
cert to another server that has the same domain (load balancing), and 
it will work. Web admins do it all the time. The user will not notice 
any difference in how the SSL will work.


Obviously. Clearly I am talking about a server in a different domain.


Up until recently, you could buy a cert for one domain, use *it* to 
issue a cert for another domain, and the major web browsers wouldn't 
kick at the traces provided you sent both certs in the ssl handshake.


Thankfully, they fixed that before *too* many phishers figured it out.


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Re: How is DNSSEC

2008-03-26 Thread Dave Howe

James A. Donald wrote:
 From time to time I hear that DNSSEC is working fine, and on examining 
the matter I find it is working fine except that 


DNSSEC is working fine as a technology. However, it is worth 
remembering that it works based on digitally signing an entire zone - 
the state of the world being what it is, most people prohibit xfer so 
any other technology that would allow a zonewalk is not going to be 
deployed.


as far as I can tell, this is a basic design flaw, so isn't going to be 
rectified anytime soon.


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Re: delegating SSL certificates

2008-03-19 Thread Dave Howe

John Levine wrote:

| Presumably the value they add is that they keep browsers from popping
| up scary warning messages
Apple's Mail.app checks certs on SSL-based mail server connections.
It has the good - but also bad - feature that it *always* asks for
user approval if it gets a cert it doesn't like.


Good point -- other mail programs such as Thunderbird also pop up
the scary warnings.  I've paid the $15 protection money for the certs
on my mail servers.


I have found that just adding the cert to the local keystore had pretty 
much the same effect. There is a nice addon for Thunderbird/Firefox 
(which will apparently be a native ability in v3 of the latter) called 
remember mismatched domains that lets you suppress an error for a 
specific cert/domain mismatch.


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Re: delegating SSL certificates

2008-03-15 Thread Dave Howe

[EMAIL PROTECTED] wrote:

So at the company I work for, most of the internal systems have
expired SSL certs, or self-signed certs.  Obviously this is bad.


Sorta. TLS gets along with self signed just fine though, and obviously 
you can choose to accept a root or unsigned cert on a per-client basis.



I know that if we had IT put our root cert in the browsers, that we
could then generate our own SSL certs.


sure. for IE its just a registry key, trivial to push out using login 
scripts etc.



Are there any options that don't involve adding a new root CA?


buying a intermediate cert from an existing CA? buying a wildcard cert 
 for your domain, and using the same wildcard cert on all nodes?



I would think this would be rather common, and I may have heard about
certs that had authority to sign other certs in some circumstances...


at one point, you could use *any* cert to sign another cert; IE didn't 
bother checking. I believe they have fixed that now.



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Re: Fixing SSL (was Re: Dutch Transport Card Broken)

2008-01-31 Thread Dave Howe

Philipp Gühring wrote:

I once implemented SSL over GSM data channel (without PPP and without
TCP), and discovered that SSL needs better integrity protection than
raw GSM delivers. (I am quite sure that´s why people normally run PPP
over GSM channels ...) SSH has the same problems. It also assumes an
active attack in case of integrity problems of the lower layer, and
terminates the connection.


TBH I can't see the problem - the unix philosophy of doing one thing
well, and chaining simple tools to make complex ones, works well here.

we have:

TCP - well understood, has crude integrity and reliability checks built
in, works reasonably well at converting a bunch of packets leaving and
arriving via your network connection into something vaguely like a
stream point-to-point connection. Provided by every ISP across the
planet, problems at this level can be handed off to experienced network
engineers who will at least understand the problem.

SSL - Cludge thrown together by a browser manufacturer, probably to
create a market for a bunch of companies who generated two prime numbers
and now sell the answers to simple math queries involving the numbers.
However, works reasonably well, has some crude authentication of the
server built in (via the aformentioned bunch of companies) which at
least limits potential hackers to those whose money the bunch of
companies will accept ;)
  Again, works well in its domain, but requires a reasonably reliable
channel to talk over, and a message to carry. Effectively turns an
unencrypted channel into an encrypted one, Would work as well over a
serial link as a tcp link (modulo the domain name check in the cert)

HTTP - pretty basic file transfer protocol, with limited scope for
negotiation, but designed largely to move text files from a server to a
client. requires transport, can use tcp, ssl-over-tcp, serial, whatever
your server will listen on and your client request on.

add them together and you get HTTPS. leave out the SSL, and you get HTTP
as-normally-spoke, so the SSL and HTTP are pretty much drop in modules.
you could define HTTPG (HTTP over a security protocol other than SSL)
and if a browser could support it, both TCP and HTTP would still be
happy. you could also define HTTPS-over-adis-lamp and provided the
operators were sufficiently accurate, securely download your web page
from a server on a nearby hilltop after dark by replacing the TCP layer :)

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Re: patent of the day

2008-01-23 Thread Dave Howe

Perry E. Metzger wrote:

http://www.google.com/patents?vid=USPAT6993661

Hat tip to a party who prefers to remain anonymous who sent me the
patent number.


Interesting. he patented E4M, then two years old or so...

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Re: Bid on a SnakeOil Crypto Algorithm Patent

2007-10-05 Thread Dave Howe

Saqib Ali wrote:

http://www.freepatentauction.com/patent.php?nb=950


googlepatent gives me:
http://www.google.com/patents?id=HaN6EBAJdq=7,088,821

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Re: Seagate announces hardware FDE for laptop and desktop machines

2007-09-15 Thread Dave Howe

Leichter, Jerry wrote:

First off, it depends on how the thing is implemented.  Since the entire
drive is apparently encrypted, and you have to enter a password just to
boot from it, some of the support is in an extended BIOS or some very
early boot code, which is below any OS you might actually have on the
disk.  
If I had to guess, I would suggest they were using the ATA secure hd 
password api, and really providing security rather than the 
firmware-lock usually associated with such passwords. That would allow 
you to retrofit it to a lot of laptops which already use that 
functionality, in a plug-and-play manner.


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Re: A crazy thought?

2007-06-09 Thread Dave Howe
Allen wrote:
 Hi Gang,
 
 In a class I was in today a statement was made that there is no way that 
 anyone could present someone else's digital signature as their own because no
 one has has their private key to sign it with. This was in the context of a
 CA certificate which had it inside. I tried to suggest that there might be
 scenarios that could accomplish this but was told impossible. Not being
 totally clear on all the methods that bind the digital signature to an
 identity I let it be; however, the impossible mantra got me to thinking
 about it and wondering what vectors might make this possible.

Awareness of the failure models of various PKI solutions is an important part of
using and designing uses for them. There are many, many failure models for the
current x509/Certification Authority model used by ssl.

(everyone already familiar with the failure modes should probably hit next
message now, unless they want to double check I am not giving out bad advice;
this email is going to get rather long :)

Consider the following steps. I will predefine three actors here -
[SITE] which for email is the *recipient*, for web traffic is the server owner.
[USER] which is the mail sender and/or site user - originator of protected data.
[CA] which is the certificate authority

1. [CA] generates and stores securely a private key

  This is a once-in-a-decade event, but even so, there are failure modes. One
  possible mode is to use political pressure (or just bad coding) to force one
  of the two primes used in RSA to be either fixed or from a very small subset
  of possible primes (aka canned primes). As you can imagine, finding the
  private key becomes near trivial if you know one of the two primes in
  advance... We can move onto the security of the key later.

2. [CA] generates and stores a public certificate using the private key

  This at least is without any real issues (except security of the private key
  of course). In practice, this would be the same operation as (1) but need not
  be.

3. [CA] transmits the public key verifiably to the end recipients

  This is actually more complex than it sounds - I would guess 99% of the keys
  everyone has on their machine (if not 100%) were supplied to them with the
  browser, or in the case of IE, preinstalled on the machine. The vast majority
  of users have no idea how to even display those keys, never mind check them.

  To verify, ask yourself this question. For each web browser or email package
  installed to your machine,

  a) Where are root keys stored?
  b) How do I view them?
  c) Where is the public key or hash I should check?
  d) where do I obtain a known-good copy of that so I can verify it?

  The answers to some of those might surprise you (for instance, IE stores its
  root certs unprotected in the registry, and your AD administrator can override
  them at will; IE keys are used by almost everything supplied by microsoft,
  including execution digital signatures and email - Outlook or OE). All are
  trivially over-ridable by an attacker with write access to your machine.

4. [SITE] Generates and stores securely a private key

  Pretty much the same provisos apply here as did for the CA. Do you know and
  can you trust your key generation software? IIS for instance relies on a tool
  supplied my microsoft for the purpose; Apache usually suggests OpenSSL, email
  clients usually use their associated web browser for an interactive generation
  of both key and CSR while connected to the CA's website. However as another
  exercise - for each, where (and how) is the private key stored and protected?

5. [SITE] Generates and forwards to the CA a certificate signing request (CSR)

  Modulo the usual private key concerns, this is usually trouble-free (and
  again, is usually a combined step with key generation)

6. [CA] Receives and (for a payment) signs the CSR with its private key.

  This is where things get interesting. The certificate generated at this stage
  may or may not use exact copies of the data in the CSR; It may or may not be
  signed directly by the CA master key (for many CA's, their master key is kept
  offline in a bank vault and used to sign an intermediate key which is used for
  actual CSRs. In fact, it may sign *multiple* intermediate keys, for a number
  of good reasons (which we won't go into at this stage) but which also
  introduce another possible attack vector for a TLA with the power to force a
  CA of his choice (or someone with access to a private key there) to do
  selected tasks.

  Several potential attacks require that this transmission to the CA be
  intercepted and fulfilled by someone other than the CA themselves.
  Conventional wisdom says that there is little or no risk caused by site
  certificate substitution, and to a great extent this is correct - other than
  the possible forcing of the symmetric encryption method to one breakable by
  the TLA, there is little or no benefit to such a substitution.

7. 

Re: the return of key escrow?

2006-02-16 Thread Dave Howe
Chris Olesch wrote:
 Ok the lurker posts...
 
 Can someone explain to me why security specialists think this:
 
 The system uses BitLocker Drive Encryption through a chip called TPM
 (Trusted Platform Module) in the computer's motherboard.
 
 is going to stop authorities from retreiving data?
 
 I ask this question on the basis of their encrypted hard drive on the
 old xbox. It supposedly used a secure key so the hard drive couldn't be
 upgraded, yet this fact didn't slow down the modd scene. Its not as if
 they are hardware encrypting tightly is it?
The old XBox didn't encrypt the data on the hard drive - instead, it used a
password on the drive firmware that almost all modern hard drives support (your
home pc's drive almost certainly supports the same thing, even if your bios 
doesn't)
Defeating the password requires one of:
a) obtaining the password
b) replacing the drive bios or controller
c) using an already unlocked drive
d) defeating the os on a running system to allow writes to the drive

all known xbox hacks used method c) or d) - using a game to bypass the write
protection, or disconnecting the ide cable after the drive was unlocked and
using a standard usbide adaptor to write to the drive.

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Re: Hiding data on 3.5 using 40 track mode

2006-02-04 Thread Dave Howe
Travis H. wrote:
 In the FBI's public statement about Hannsen, they relate how he used a 3.5 
 floppy in 40 track mode to store data, but if it was read in the ordinay
 way it would appear blank.  IIRC, high-density floppies are 80 tracks per
 inch, and double density were 40 tpi.  So, how do you suppose this trick
 works? The official details are, of course, vague

  It would have to be a guess.

  Back in the 5 1/2 days, we would frequently use a disk on both standard and
1.2mb drives; on the 1.2s, the head was literally half the width of a standard
5.25 drive, so you got the occasional problem due to this.

  For virgin disks, reading a file written on a 1.2 on a standard was no
problem; writing *any* disk on a standard always worked

  After a bit of use though, a interesting but predictable problem emerged - if
you wrote a file on a standard, then overwrote that file on a 1.2, then only
half the track (the lowest half) would be overwritten; the other half would
retain its original data, and a standard drive attempting to read back the data
would in fact read unreliably.

  Applying this to the problem would seem to suggest that, if you format a
standard 1.44 floppy as a 720, only *alternate* tracks are actually formatted,
and the intervening tracks are left blank.

  If you wrote and installed a special driver, you could read and write those
*alternate* tracks independently of the formatted tracks; even in a classic
720 3 1/2 drive, the worst you could expect would be an unreliable read, and
the best would be that you would get a reliable read from the real tracks,
ignoring the interleaved alternates. Of course, reading this floppy on a normal
1.44mb drive would show nothing wrong, and read it as being a perfectly usable
720K floppy. of course, *why* you would want to do that is another issue.

  Oh - before I forget, I was thinking about covert channels and cds a few days
ago and realised there is already one - CDs support a special mode called CD+G
- this is used making karaoke cds to support the video data stream; the vast
majority of pc drives cannot read this data - there are exceptions of course.
however, karaoke players (and many low-end dvd players) CAN, and by design
display them on the screen of the playback device.  This is pretty much STO, but
could conceal a message trivially that normal examination of the cd would not
reveal, but which the recipient could display (again, trivially) using nothing
more than a tv set and cheap mass-produced DVD player.

  Needless to say, you could always write or read data from the low bits of the
audio too, provided you got a reliable read of that data... the software to do
that could be considered suspicous though, while a cd that has a short text
message imbedded in track #12 of a 20 track audio collection would be harder to
detect (but of course for even vague security would have to be treated as a steg
channel and encrypted in addition, with something decodable by hand like a book
code)

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Re: [EMAIL PROTECTED]: Re: thoughts on one time pads]

2006-01-31 Thread Dave Howe
Eugen Leitl wrote:
 Sudden thermal stress (liquid nitrogen, etc) might be good enough to
 delaminate, leaving clear disks behind.

Not sure what the data surface is made from but - surely a suitable organic
solvent could remove the paint into suspension leaving a clear plastic disc
and no trace of organized data?

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Re: thoughts on one time pads

2006-01-28 Thread Dave Howe
John Denker wrote:
 Dave Howe wrote:
 
 Hmm. can you selectively blank areas of CD-RW?
 
 
 Sure, you can.  It isn't s much different from rewriting any
 other type of disk.
Yeah, I know. just unsure how effective blanking is on cd-rw for (say) a pattern
that has been in residence for two years, but now must be unrecoverable.


 There are various versions of getting rid of a disk file.
  5) Grinding the disk to dust.  AFAIK this is the only NSA-approved
   method.  A suitable grinder costs about $1400.00.
http://cdrominc.com/product/1104.asp
for most, scratching off the carrier substrate is usually enough - I *might* be
persuaded some trace remains on the plastic disc afterwards, but I can't imagine
anyone recovering from a disk that had been
a) scraped clean then
b) thrown into a blast furnace containing liquid iron, or even a small home 
smelter.

However, I am more interested in methods to destroy just a single track at a
time, and I doubt you could deface the disk reliably *and* still retain read
abilty on the remaining tracks.

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Re: a crypto wiki

2006-01-28 Thread Dave Howe
Anton Stiglic wrote:
 I agree.  The cryptodox page looks nice, but I would rather see the content
 go in wikipedia, which is worked on, and looked at, by many more people, a
 really beautiful community work.
There is also the wiki crypto wikibook, which is sorta a co-production and
shares a lot of text with the wiki crypto entries. The idea is to get a slightly
more fixed view of the pages, which can then be published in paper form.

http://en.wikibooks.org/wiki/Cryptography

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Re: thoughts on one time pads

2006-01-27 Thread Dave Howe
Jonathan Thornburg wrote:
 1. How to insure physical security for the N years between when you
 exchange CDs and the use of a given chunk of keying material?  The
 single CD system is brittle -- a single black-bag burglary to
 copy the CD, and poof, the adversary has all your keys for the next
 N years.
Hmm. can you selectively blank areas of CD-RW?

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Re: [Clips] Sony to Help Remove its DRM Rootkit

2005-11-04 Thread Dave Howe
R.A. Hettinga wrote:
 http://www.betanews.com/article/print/Sony_to_Help_Remove_its_DRM_Rootkit/1130965475

Unfortunately, this is an exaggeration of what Sony have agreed to do - they
have issued an installable which removes the filename cloaking component while
leaving the rest (primarily, the cd rom driver chain filters in place. It is
still not possible to remove these other than manually (and yes, the system as a
whole still uses up cpu and memory for no benefit other than for sony (and even
then, its a trivial hack to prevent the DRM from installing in the first place -
just disable autorun, which anyone halfway paranoid does anyhow)
  Mind you, sony seem to have added another wrinkle to this story with their new
DRM - which is aimed, not at preventing p2p copies, but at isolating Sony CDs
from itunes
  http://bigpicture.typepad.com/comments/2005/10/drm_crippled_cd.html

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Re: Is there any future for smartcards?

2005-09-13 Thread Dave Howe
Eugen Leitl wrote:
 On Sun, Sep 11, 2005 at 06:49:58PM -0400, Scott Guthery wrote:
1) GSM/3G handsets are networked card readers that are pretty
successful.  They are I'd wager about as secure as an ATM or a POS,
particularly with respect to social attacks.
 The smartphones not secure at all, because anything you enter
 on the keypad and see on the display can be compromised, so
 the tamper-proof cryptographic goodness locked inside the SIM
 smartcard will cheerfully approve whatever the code running
 on the smartphone will tell it to approve, regardless of
 what is being displayed to the user.
  TBH I don't think the smartcard approach will work - really, everything needed
to verify what you are signing or encrypting needs to be within your secure
boundary, so the only sensible approach is for a mobile-sized cryptographic
device to be autonomous, but accept *dumb* storage cards for reading and
writing; that dumb card can then be used to transfer a unsigned document to the
cryptographic device, which when inserted uses a relay or switch to assume
control of the keyboard and screen; person wishing a digital signature stores
the document to be signed onto the card; signer inserts into his device, uses
the device's display to assure himself this is really what he wants to sign and
then keys his access code. The device then produces a digital signature
certificate (possibly deliberately adding some harmless salt value to the end
before signing, which is noted in the detached certificate's details) and copies
that to the dumb card, retaining a copy for the user's own records.
  by using a switch controlled by the cryptographic module, the display can be
then used by an alternate system when not in use - for example, a mobile phone -
while providing an airgap between the secure module and the insecure (and yes,
this would mean if you received a contract via email, you would have to write it
to a card, remove that card from a slot, insert it into a different slot, then
check it. I can't see how the system can be expected to work otherwise)

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Re: Another entry in the internet security hall of shame....

2005-08-29 Thread Dave Howe

Peter Gutmann wrote:

TLS-PSK fixes this problem by providing mutual authentication of client and
server as part of the key exchange.  Both sides demonstrate proof-of-
possession of the password (without actually communicating the password), if
either side fails to do this then the TLS handshake fails.  Its only downside
is that it isn't widely supported yet, it's only just been added to OpenSSL,
and who knows when it'll appear in Windows/MSIE, Mozilla, Konqueror, Safari,
So, the solution to nobody using the existing (but adequate) solution is another 
existing (but barely implimented and also unused) solution?


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Re: Another entry in the internet security hall of shame....

2005-08-29 Thread Dave Howe

James A. Donald wrote:
SSL works in practice, X509 with CA certs does not work 
in practice.  People have been bullied into using it by 
their browsers, but it does not give the protection 
intended, because people do what is necessary to avoid 
being nagged by browsers, not what is necessary to be 
secure. 
  Indeed so - however, if Google makes it just work then there will be a 
large swathe of people out there wondering what does this DIGITAL SIGNATURE 
button do in gmail? plus a smaller subset who have google talk and can perform 
secure e2e voip using x509 certs that they don't even know they have.
  Its not ideal, but its not a bad thing either - a little more security, using 
a known method, without any individual user having to know or care how it works 
(and lets face facts here, no solution that requires an end user to get his 
finger out and do something without being forced to, no matter how trivial the 
task is, ever had a decent update)


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Re: Another entry in the internet security hall of shame....

2005-08-28 Thread Dave Howe

Nicolas Williams wrote:

Yes, a challenge-response password authentication protocol, normally
subject to off-line dictionary attacks by passive and active attackers
can be strengthened by throwing in channel binding to, say, a TLS
channel, such that: a) passive attacks are not possible, b) MITMs below
TLS get nothing that can be attacked off-line, and c) server
impersonators can be detected heuristically when the attacker can't
retrieve the password in real-time (such an attack is indistinguishable
from password incorrect situations, but...).
  Indeed. The main problem with TLS is lack of PKI support; in principle, this 
isn't true - TLS uses X509 certs, just like any other SSL based protocol - but 
in practice, everyone uses self signed certificates and nobody checks them or 
even caches them to see if they change.


  So - interesting idea time. what if

1) Talk strongly authenticated *all* connections, even p2p ones, using a 
GoogleMail master certificate and a Googletalk.Googlemail single-use certificate 
to authenticate the GoogleMail server.


2) Google got into the CA business; namely, all GoogleMail owners suddenly found 
they could send and receive S/Mime messages from their googlemail accounts, 
using a certificate that just appeared and was signed by the GoogleMail master 
cert. Given the GoogleMail user base, this could make GoogleMail a defacto CA in 
days.


3) This certificate was downloaded to your GoogleTalk client on login, and NEVER 
cached locally


  Ok, from a Security Professional's POV this would be a horror - certificates 
all generated by the CA (with no guarantees they aren't available to third 
parties) but it *would* bootstrap X509 into common usage, and takeup of s/mime 
certificates was always the bottleneck for getting encrypted mail to go 
mainstream (PGP has the same problem, but in addition has the WoT issues and up 
to recently actual obtaining of the software to contend with)


  I can only hope that if this *is* in the gameplan, that the certificates be 
marked autogenerated so that in the longer term a more conventional, 
clientside-generated certificate can be used instead.


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Re: Another entry in the internet security hall of shame....

2005-08-26 Thread Dave Howe

Ian G wrote:

none of the above.  Using SSL is the wrong tool
for the job.  
For the one task mentioned - transmitting the username/password pair to the 
server - TLS is completely appropriate.  However, hash based verification would 
seem to be more secure, require no encryption overhead on the channel at all, 
and really connections and crypto should be primarily P2P (and not server 
relayed) anyhow.


 It's a chat message - it should be

encrypted end to end, using either OpenPGP or
something like OTR.  And even then, you've only
covered about 10% of the threat model - the
server.
yeah. you have a unencrypted interchange point - the server. There are aspects 
to that which make it both a good and bad thing, mostly bad. for example you 
allow interception at the server (may be a requirement for an american based 
company, but still bad), and you provide a single point of failure for hackers 
(very bad)
Most of the good aspects revolve around only having to support one client cert 
you can embed in your own client (or make available on your website) and not an 
entire PKI infrastructure.


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Re: solving the wrong problem

2005-08-07 Thread Dave Howe

Ilya Levin wrote:

John Denker [EMAIL PROTECTED] wrote:


So, unless/until somebody comes up with a better metaphor,
I'd vote for one-picket fence.



Nonsense fence maybe less metaphoric but more clear.
I disagree - one picket fence gives a clear impression of a protective device 
that is hardened at but one point - leaving the rest insecure. nonsense fence 
doesn't give any real image.


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Re: aid worker stego

2005-05-20 Thread Dave Howe
Peter Fairbrother wrote:
I don't think there is much danger of severe torture, but I don't think
innocent-until-proven-guilty applies either, and suspicion should be
minimised or avoided.
Depends on what you want to avoid.
Best solution for software is dual-use - 7-zip for file encryption, 
standard s/mime capable email software (such as thunderbird or even 
outlook express) for pki. However, encrypted emails are *always* going 
to stick out like a sore thumb if intercepted, and even the output of 
most stego packages will look suspect (unless your aid worker is in the 
habit of sending large numbers of digital photos by email. This could be 
arranged - get him to take new, original photos of what he sees while 
doing his work, use them exactly once for stego, then keep the stegoed 
versions around on the hd so that any comparison later will show the 
original version identical to the intercepted email version.

Probably the best overall solution to this would be a bootable mini-cd; 
a mini-linux distro would give a gui, and still leave room for 
conventional encryption packages, stego packages and the user's 
secret/public keyring, leave no trace on the HD at all (no matter how 
good the forensic package), can be hidden in a wallet amongst credit 
cards, and can be distroyed trivially by simply scratching off the 
printed surface with the back of a key or against a rough surface such 
as a wall or stone paving slab (ie, drop it face down, then stand on it 
and move foot back and forth until you have an oblong of worthless 
plastic and a slightly messy walkway)

assuming stego, you could load digicam photos (either via a driver on 
the minicd or via windows, whichever you happen to be using at the time) 
not long after they were taken, for later stego purposes, and the space 
they use on the digicam reused for more photos before the first set were 
used for stego (or again, if in a hurry, just remove and discard the sd 
card from the cam)

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Re: SHA1 broken?

2005-02-17 Thread Dave Howe
Joseph Ashwood wrote:
  I believe you are incorrect in this statement. It is a matter of public
record that RSA Security's DES Challenge II was broken in 72 hours by 
$250,000 worth of semi-custom machine, for the sake of solidity let's 
assume they used 2^55 work to break it. Now moving to a completely 
custom design, bumping up the cost to $500,000, and moving forward 7 
years, delivers ~2^70 work in 72 hours (give or take a couple orders of 
magnitude). This puts the 2^69 work well within the realm of realizable 
breaks, assuming your attackers are smallish businesses, and if your 
attackers are large businesses with substantial resources the break can 
be assumed in minutes if not seconds.

2^69 is completely breakable.
   Joe
  Its fine assuming that moore's law will hold forever, but without 
that you can't really extrapolate a future tech curve. with *todays* 
technology, you would have to spend an appreciable fraction of the 
national budget to get a one-per-year break, not that anything that 
has been hashed with sha-1 can be considered breakable (but that would 
allow you to (for example) forge a digital signature given an example)
  This of course assumes that the break doesn't match the criteria 
from the previous breaks by the same team - ie, that you *can* create a 
collision, but you have little or no control over the plaintext for the 
colliding elements - there is no way to know as the paper hasn't been 
published yet.

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Re: Quantum cryptography gets practical

2004-10-06 Thread Dave Howe
Dave Howe wrote:
 I think this is part of the
purpose behind the following paper:
http://eprint.iacr.org/2004/229.pdf
which I am currently trying to understand and failing miserably at *sigh*
Nope, finally strugged to the end to find a section pointing out that it 
does *not* prevent mitm attacks.
Anyone seen a paper on a scheme that does?

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Re: IBM's original S-Boxes for DES?

2004-10-05 Thread Dave Howe
Steven M. Bellovin wrote:
It was only to protect against differential cryptanalysis; they did not 
know about linear cryptanalysis.  
  More accurately, they didn't protect against linear cryptanalysis - 
there is no way to know if they knew about it and either didn't want to 
make changes to protect against that (they weakened the key, so may have 
wished to keep *some* attacks viable against it to weaken it still 
further), had to choose (against *either* differential or linear, as 
they didn't know how to protect against both) or simply the people doing 
the eval on DES didn't know, as it was rated above their clearance level.
  We only have a single event to go from (that DES was indeed protected 
against one not the other) so can't really judge motivation or knowledge.

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Re: They Said It Couldn't Be Done

2004-09-20 Thread Dave Howe
R. A. Hettinga wrote:
Nevada has taken the lead on paper trails not only in its own elections,
but also in Congress. Its senators - John Ensign, a Republican, and Harry
Reid, a Democrat - have co-sponsored the bipartisan Voting Integrity and
Verification Act, one of a number of pending bills that would require that
all electronic voting machines produce voter-verifiable paper trails.
Congress should pass such legislation right away so all Americans can have
the same confidence in their elections as Nevadans now have.
I must admit I am surprised a new law is needed.
Under the Help America Vote Act 2002 electronic voting machines appear 
to have the following audit requirement:

   TITLE III--UNIFORM AND NONDISCRIMINATORY ELECTION TECHNOLOGY AND
  ADMINISTRATION REQUIREMENTS
   Subtitle A--Requirements
SEC. 301. NOTE: 42 USC 15481 VOTING SYSTEMS STANDARDS.
   (a) Requirements.--Each voting system used in an election for
Federal office shall meet the following requirements:
   (2) Audit capacity.--
   (A) In general.--The voting system shall produce a
   record with an audit capacity for such system.
   (B) Manual audit capacity.--
 (i) The voting system shall produce a
 permanent paper record with a manual audit
 capacity for such system.
 (ii) The voting system shall provide the voter
 with an opportunity to change the ballot or
 correct any error before the permanent paper
 record is produced.
 (iii) The paper record produced under
 subparagraph (A) shall be available as an official
 record for any recount conducted with respect to
 any election in which the system is used.
(taken from http://www.fec.gov/hava/law_ext.txt )
So unless there is a amendment to that law (that I am obviously unaware 
of) it isn't up to individual States to add this as an additional 
requirement - its already required. perhaps someone could enlighten me?

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Re: How a Digital Signature Works

2004-08-12 Thread Dave Howe
R. A. Hettinga wrote:
 The publisher first has to obtain a digital certificate from a recognized
certificate authority or CA (VeriSign (VRSN ) is the largest and best
known CA in the U.S.). The publisher receives a private and a public key,
each of which is a long number of about 300 digits. These are used to
create a digital signature for each program (see BW Online, 8/10/04,
Windows of Vulnerability No More?).
And which will guarantee to... erm... *try* not to sell the same 
certificate to someone else, or to at least notice if they do (provided 
it has a famous name on it like microsoft of course)

and what is new about MS's signed executable support? its been around 
long enough...

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Re: Use cash machines as little as possible

2004-07-07 Thread Dave Howe
Anne  Lynn Wheeler wrote:
ONE of Britain's biggest banks is asking customers to use cash
machines as little as possible to help combat soaring card fraud.
That's odd - given a deliberate policy of encouraging Cash Machine use 
over the last few years, as Cash Machine costs+fraud still come to less 
than the running costs of sufficient local branches to allow you to 
obtain *Your* money back from them when needed

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Re: Yahoo releases internet standard draft for using DNS as public key server

2004-06-01 Thread Dave Howe
Ed Gerck wrote:
No -- DomainKeys has nothingf to do with 'email cryptography'. They are
S/MIME and PGP/MIME.
I wouldn't say PGP/MIME (as opposed to pgp inline) was a widely enough 
used standard to be considered one of two options - pgp (both methods) 
certainly, but not pgp/mime exclusively.

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Re: Yahoo releases internet standard draft for using DNS as public key server

2004-06-01 Thread Dave Howe
Peter Gutmann wrote:
It *is* happening, only it's now called STARTTLS (and if certain vendors
(Micromumblemumble) didn't make it such a pain to set up certs for their MTAs
but simply generated self-signed certs on install and turned it on by default,
it'd be happening even more).
TLS for SMTP is a nice, efficient way to encrypt the channel. However, 
it offers little or no assurance that your mail will *stay* encrypted 
all the way to the recipients.
Most of us (including me most of the time) are in the position of using 
their ISPs or Employer's smarthost to relay email to its final 
destination; in fact, most employers (and many ISPs) actually enforce 
this, redirecting or blocking port 25 traffic.
If my employer or isp accept TLS traffic from me, but then turn around 
and send that completely unprotected to my final recipient, I have no 
way of preventing or even knowing that.
Sendmail's documentation certainly used to warn this was the case - 
probably still does :)

How many messages to the Cryptography Mailing List are cryptographically
signed?
The S/MIME list debated this some time ago, and decided (pretty much
unanimously) against it, for two reasosn.  Firstly, because it adds huge ugly
blobs of base64 crap to each message (and before the ECC fans leap in here,
that still adds small ugly blobs of base64 crap to each message).  Secondly,
because if you get a message from someone you know you'll be able to get a
pretty good idea of its authenticity from the content (for example an SSH
developer would be unlikely to be advocating SSL in a list posting), and if
you get a message from someone you don't know then it's pretty much irrelevant
whether it's signed or not.  So the consensus was not to sign messages.
Agreed.  In cases of spoofing, there could of course be an issue - but 
lets be honest here; when was the last time a mailing list regular 
*anywhere* lost reputation because someone posted spam or trollishness 
to the list in their name?
I am not saying that doesn't happen - but it is rare, and usually the 
real poster points out the difference in header data that would indicate 
that email came from a source other than him.

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Re: A National ID

2004-06-01 Thread Dave Howe
R. A. Hettinga wrote:
If we're going to move to a national identification card, we can't afford
to do it badly. Now is the time to figure out how to create a card that
helps identify people but doesn't rob them of a huge swath of their civil
liberties in the process.
Just watch how the british do it - then don't do it that way.
I am still trying to figure out how over a decade of terrorist bombings 
in mainland UK didn't justify introducing a national ID card - but the 
americans wanting biometric passports for visitors does.

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Re: Software Helps Rights Groups Protect Sensitive Information

2004-06-01 Thread Dave Howe
R. A. Hettinga wrote:
To prevent loss or theft, the data is backed up automatically and
redundantly on dedicated Martus servers in Manila, Toronto, Seattle and
Budapest. Nobody can read the files without access to the original user's
cryptography key and password -- with the exception of sophisticated
code-cracking organizations such as the U.S. National Security Agency or
China's Public Security Bureau.
I might be missing something here but - exactly how does a system 
insecure enough that interested governments can crack it help protect 
people who are releasing information concealed by those governments?

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Re: Yahoo releases internet standard draft for using DNS as public key server

2004-06-01 Thread Dave Howe
Ian Grigg wrote:
Dave Howe wrote:
No - it means you might want to consider a system that guarantees 
end-to-end encryption - not just first link, then maybe if it feels 
like it
That doesn't mean TLS is worthless - on the contrary, it adds an 
additional layer of both user authentication and session encryption 
that are both beneficial - but that *relying* on it to protect your 
messages is overoptimistic at best, dangerous at worst.
This I believe is a bad way to start looking
at cryptography.  There is no system that you
can put in place that you can *rely* upon to
protect your message.
No, there are plenty that you can rely on to protect your message while 
still in transit.
If you can ensure that the only possible points of vulnerability are at 
the two endpoints, then you and your correspondent take control of your 
security - it won't be perfect, as you point out - but you won't be 
reliant on the goodwill and efforts of some third party whose most 
economic option is to accidentally or deliberately neglect TLS between 
your local smart host and your correspondent's email spooler, or indeed, 
to supply minimal security to the email spools at smarthost or destination.

(Adi Shamir again: #1 there are no secure systems,
ergo, it is not possible to rely on them, and
to think about relying will take one down false
paths.)
Secure systems exist - but are rarely worth the effort involved.
Many PDAs can handle PGP or S/Mime traffic these days - certainly, you 
could offload your message (already encrypted) to flash media, insert 
into sending host, receive (from email spool) at the destination and 
transfer to flash media, then insert into decoding PDA.  To compromise 
either PDA would require access - so if you keep it about your person 
(and within sight when you bathe), you should be safe against anything 
but a midnight intrusion with sleeping gas
But regardless - the level of defence required is proportional to the 
likely threat.  It is entirely possible that it would be worthwhile for 
some hacker to compromise a router between your ISP's mail server and 
your correspondent's spool, or that spool itself. It is less likely that 
it would be worth someone's while to break into your home with exquisite 
timing and tracelessly alter software on your trusted airgapped machine 
while you shower (and if that *is* your threat model, I envy the income 
you must get to justify being in such a position or bow to the value of 
your information to some repressive regime)

Otherwise, we adopt what military people call
tactical security:  strong enough to keep
the message secure enough so that most of the
time it does the job.
Indeed so.
The principle which needs to be hammered time
and time again is that cryptography, like all
other security systems, should be about risk
and return - do what you can and put up with
the things you can't.
Again, true. I suspect we differ in what we consider an acceptable risk 
- I don't consider any setup where the security of the channel is 
against the best interests of the people controlling that channel 
acceptable - especially where I have no way to discover if that channel 
was compromised.
I have what I hope is an acceptably secure system at home - and I also 
hope my correspondents do likewise. If our messages are compromised (not 
that they contain anything worth stealing) then it is my fault or theirs 
- not an admin at the isp, or some minimum-wage employee on a helpdesk 
bribed to let someone take a peak at my mailspool. This extra security 
comes free, gratis, not a penny does it cost - beyond the effort of 
learning how to use it - and while I was used to hotkeying my way into 
the current window, my recent switch to Enigmail means I don't even have 
to do that. Why would I settle for less?

Applying the specifics to things like TLS and
mail delivery - yes, it looks very ropey.  Why
for example people think that they need CA-signed
certs for such a thing when (as you point out)
the mail is probably totally unprotected for half
the journey is just totally mysterious.
And indeed I had a conversation with someone who was interested in a 
secure mailing list only a few days ago. I suggested he not bother and 
 just set up a HTTPS website with any one of a dozen BBoard systems and 
local certificate support - because that was free and all the complexity 
(and most of the vulnerabilites) are at the server side - while setting 
up a secure email burster would be almost impossible and would rely on 
not only training the end users, but ensuring they have the right 
software installed.

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Accoustic Cryptoanalysis for RSA?

2004-05-25 Thread Dave Howe
opinions?
http://www.wisdom.weizmann.ac.il/~tromer/acoustic/

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Vulnerability in the WinZip implimentation of AES?

2004-05-25 Thread Dave Howe
http://www.cse.ucsd.edu/users/tkohno/papers/WinZip/

 Abstract: WinZip is a popular compression utility for Microsoft Windows
computers, the latest version of which is advertised as having
easy-to-use AES encryption to protect your sensitive data. We exhibit
several attacks against WinZip's new encryption method, dubbed AE-2 or
Advanced Encryption, version two. We then discuss secure alternatives.
Since at a high level the underlying WinZip encryption method appears
secure (the core is exactly Encrypt-then-Authenticate using AES-CTR and
HMAC-SHA1), and since one of our attacks was made possible because of the
way that WinZip Computing, Inc.~decided to fix a different security
problem with its previous encryption method AE-1, our attacks further
underscore the subtlety of designing cryptographically secure software.

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Re: Do Cryptographers burn?

2004-04-04 Thread Dave Howe
Hadmut Danisch wrote:
 - He didn't find any single mistake. He just says that everything is
   already known and taken from literature.
certainly possible - if he didn't know (or deliberately ignored) that it had
been written in 1988 :)
How much of it is *still* new or at least hard to find in the literature?
how much of it would be known *today* out of hand by someone who was
familiar with the state of the art?  If the university had instructed him to
take a look at your work in that context, he may well not have found
anything new or novel in there - because your work had since been
duplicated, and after 16  years I would expect it to have been duplicated
several times.  If he had been instructed to find pre-1987 published work
that duplicated yours, that would be different - but I would assume the
university neglected that direction while instructing him.

 Maybe it's a minority writing false expertises. But it's a majority
 accepting that.
We have the same problem with expert witnesses in court here in the uk -
after a while, prosecutors learn which experts can be relied on to give the
answer they want rather than admit it is a matter of opinion and either case
could be correct - such experts get a lot more work from the prosecution for
their unbiassed opinions than those which gave an unbiassed opinion the
prosecution didn't like (it isn't unknown for the prosecution to approach
three or four experts and take the most favourable return to court)

 So my doubt is not so much about that someone found the magic way to
 factorize. It's about someone intenionally selling snake-oil or
 backdoors and other's keeping their mouth shut and tolerate this as
 they do it here.
no, it isn't.
it is about someone deliberately choosing to concentrate on the worst
aspects of a 16 year old dissertation (almost certainly, that it is 16 years
out of date) and ignoring the context. I am sure if I paid 100 experts to
evaluate *anything* I could find at least one I liked the resulting report
from.
I am not too surprised either - for the reasons I have detailed above. I
know it is hard to have fought this way though the legal system to find the
university has tried to throw money at the problem to make it go away - but
it happens, and I can only assume you will eventually prove it in court.
what you have here is a legal problem with some individuals, that their
employer has chosen to back against a student, and in doing so bent any or
all rules it could to win. This says little about the individual who wrote
the new examination and more about your opponents in the university's legal
team.  BTW is there any way you can find out how many experts were asked
to evaluate your work before they found one whose answer they liked?

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Re: Do Cryptographers burn?

2004-04-03 Thread Dave Howe
 Do Cryptographers burn?
Sometimes they blush hard enough to ignite, if that helps :)

 Cryptography is a lot about math, information theory,
 proofs, etc. But there's a certain level where all this
 is too complicated and time-consuming to follow all those
 theories and claims. At a certain point cryptography is based
 on trusting the experts.
  This is universally true though - nobody can live long enough to work
though the theory and practical of almost anything - consider for example a
classic (no computer engine or breaking control) automobile. You would need
to understand every part of chemical theory that relates to petroleum
fractions and additives commonly found in car fuel; thermodynamic, materials
and physical theory and engineering design that relates to the functions of
the engine and its mechanical coupling to the drive wheels; the
differential, the gearing, the steering, the breaking, the materials that
form the tyres, the ergonomic design of the seating area, vision angles
though the windshield, glass (materials) theory for the material that forms
the windshield (toughness, resistance to random impacts, refraction though
the medium), the materials of the road surface and how they behave under
different conditions of wet, dry, temperature... and that is just the
generic stuff. once you get down to a specific instance, you have to decide
if your instance of car meets the theoretical data you learnt on a abstract
car, and if the instance of road you are driving on meets similar data you
have on abstract driving surfaces.
  Even those who work in that field can take decades to reach the point they
could design one component of a modern automobile - the engine, the gearbox,
the chassis and so on. It would be insane to learn all that if you just
wanted to drive to work in the mornings
  At a basic level, you have to define basic functions in terms that an
expert can verify and say yes, that is a truism - then you can drop them
into more complex systems in different patterns, not knowing if the system
will work but able to rely on the components to perform within their design
parameters. the same is true of cryptography; an accepted algo will have
been hammered on and peer reviewed by dozens of people - and as even a minor
predictability under extreme conditions using a simplified form of an algo
is worth writing up a paper on, there is a world of pre-established work to
review and verify for even the most ambitious would-be-cryptoanalyst to cut
his teeth on (and use as training examples to apply similar techniques to
algos that have not yet had that attack publically attempted on them)
  So,if the basic level for a mathematician is the maths within the
algorithm; the basic level for a programmer is the algorithm itself, as a
process to produce cryptotext from plain, or plaintext from crypto.
Normally, a programmer won't worry about verifying the algo - he will accept
that as part of the design he is to impliment, and if he has a choice of
several suitable algos, will simply impliment them all as alternative
settings.
  Programmers love to re-use code though - it saves a *lot* of work, and as
you become familiar with and improve the code you can feed back changes to
earlier software, improving its efficiency for free. Of course for this to
work well, the code must be independent of the body of the software, have
clearly defined interfaces (so that you can't mess up an earlier
implimentation when improving a later one, by forgetting a side effect you
earlier relied on but don't need any more) and indeed act as a basic
component itself - forming a subprogram that you hand data to and receive
data back from as a black box operation. Another strength of doing your
crypto as such a library of pre-written code is that you can test and
prove it independently of your main program - you can hand your crypto
library to your peers for their review, you can encourage its use (thus
ensuring good crypto in a wide range of software, improving compatability,
and not incidentally improving your peer reputation :) and generally
maintain your library as a product in its own right.
  At the end of the chain is a programmer who doesn't want to know about how
the algo works, would rather not have to know the details of how to make it
work, but likes the idea of being able to write something like

use MyFirstCryptoLibrary;
ask user for message store in [messagedata]
ask user for key store in [key]
DoCrypto(chosenalgo,[key],[messagedata]) store in [encrypted message]
ask user for destination store in [EmailToName]
SendEmailTo([EmailToName],[encrypted message])

and have it work. and indeed, until the average programmer *can* use a
library that easily to include decent crypto in his product, the majority of
the products out there will be either not supporting crypto at all, or doing
it badly.

 Is anyone here on this list who can
 claim to have read and understood all those publications
 about cryptography?
I can 

Re: PKI root signing ceremony, etc.

2003-12-15 Thread Dave Howe
Peter Gutmann wrote:
 Dave Howe [EMAIL PROTECTED] writes:
 Key management and auditing is pretty much external to the actual
 software regardless of which solution you use I would have thought.

 Not necessarily.  I looked at this in an ACSAC'2000 paper (available
 from http://www.acsac.org/2000/abstracts/18.html).  This uses a
 TP-capable database as its underlying engine, providing the necessary
 auditing capabilities for all CA operations.  This was desgined to
 meet the security/auditing requirements in a number of PKI standards
 (see the paper for full details, I've still got about 30cm of paper
 stacked up somewhere from this).  The paper is based on
 implementation experience with cryptlib, you can't do anything
 without generating an audit trail provided you have proper security
 on the TP system (that is, a user can't inject arbitrary transactions
 into the system or directly access the database files).  I tested the
 setup by running it inside a debugger and resetting/halting the
 program at every point in a transaction, and it recovered from each
 one.  It can be done, it's just a lot of work to get right.
*nods*
I meant in this context - certainly, a well designed CA package would
enforce security and audit trailing (I can easily visualise one that uses
a composite (split) access key n of m, and could probably code up such a
tool in a day or so) but Rich's original design had no audit or key
management other than that imposed externally on the (essentially
flatfile) stucture of Openssl command line tools.

 I should mention after having done all that work that most CAs rely on
 physical and personnel security more than any automatic
 logging/auditing. Take a PC and an HSM, lock it in a back room
 somewhere, and declare it a secure CA.
*nods* and that is probably as secure as any other method, and a *lot*
more secure than a safe exe running on insecure hardware.

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Re: Cryptophone locks out snoopers

2003-11-26 Thread Dave Howe
Ian Grigg wrote:
 (link is very slow:)
 http://theregister.co.uk/content/68/34096.html
 
 
 Cryptophone locks out snoopers
 By electricnews.net
 Posted: 20/11/2003 at 10:16 GMT
 I see the source release has been put back... again.

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Re: Test of BIOS Spyware

2003-10-16 Thread Dave Howe
Ralf-P. Weinmann wrote:
 This is *NOT* the interesting part. The interesting part is the
 payload it is to deliver. The claim This enables the software to spy
 on the user and remain hidden to the operating system. rather
 interests me. How do they achieve this in an OS-agnostic fashion?
They won't even try - I am under the impression this is for use as a
black bag job, possibly even remotely; they can target the machine with
a specific update for the currently running OS.

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Re: Easy VPNs?

2003-10-11 Thread Dave Howe
Ian Grigg wrote:
 I'm curious - my understanding of a VPN was that
 it set up a network that all applications could
 transparently communicate over.
spot on.

 Port forwarding appears not to be that, in
 practice each application has to be reconfigured
 to talk to the appropriate port, or, each port
 has to be forwarded.
also correct

 Am I missing something here?  If there is an
 easy SSH based strategy for VPNs, what is it?
what you are missing is joining the dots. the VPN part requires that a
server process be running that intercepts packets destined for the
remote end of the VPN (usually a virtual network card or ip stack shim).
That says nothing about how the data gets from *that* intercept server to
the matching server at the receiving end - the transport method.
IPSec uses an assortment of custom ip types and standard tcp/udp
connections. ssl vpn uses an ssl encrypted tcp/ip connection, but there
is no reason why the two intercept servers couldn't talk to each other
over (for example) a ssh tunnel, zebedee, or whatever else takes its
author's fancy.
In practice, you want the tunnel to have low overhead, so udp is often
used; tcp however traverses nat and pat servers much more easily and the
additional convenience of ssh transport (being an existing, established
standard that uses only a single port and that firewalls - and their
admins - are already familiar with) may be of more value than the more
complex and less well understood (and damned hard to get though anything,
including firewalls) IPSec.

so as I say - think of vpn as two components - intercept (the virtual
network functionality) and transport (a secure, authenticated,
encapsulated communications standard) and how vpn over *anything* becomes
more clear.

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Re: Monoculture

2003-10-02 Thread Dave Howe
slightly ranting, you might want to hit del now :)
Ian Grigg wrote:

 What is written in these posts (not just the present one)
 does derive from that viewpoint and although one can
 quibble about the details, it does look very much from
 the outside that there is an informal Cryptographers
 Guild in place [1].

 I don't think the jury has reached an opinion on why
 the cryptography group looks like a guild as yet,
 and it may never do so.  A guild, of course, is either
 a group of well-meaning skilled people serving the
 community, or a cartel for raising prices, depending
 on who is doing the answering.
To me it seems more like a academic community - particularly the way many
can't handle the concept of good enough but look for theoretically
perfect solutions that may be unworkable in the Real World.  And yes, I
*am* an outsider - I dabble a little, and I am a programmer, but I am the
first to admit my math skills are nowhere near adequate to make any
meaningful contribution to the field.
It seems to me there is no more a cryptography guild than a linux guild -
yes, you get advocates who foam at the mouth if you say the wrong thing,
but the majority seem more interested in getting it to work.  From my POV
as a programmer, learning the field consists of identifying the
available building blocks (hash, symmetric, asymmetric), standards
(openpgp, x509, ssl, ssh, ipsec) and prior implimentations (paying
particular attention to what had to be patched due to discovered
vunerablities, so as to avoid the same errors in my own code)
It also seems the crypto community is very open to questions, very hostile
to statements - so often knowing how to phrase something to them is as
important as the content of the question. Stating I am doing $FOO will
not be as productive as If I were to do $FOO what vunerabilities would
that introduce? - remembering that any good advice you get back for free
would have probably cost you weeks of study or possibly thousands of
dollars trying to obtain a security certification for your solution later
on.
Just ignore any posts of because it isn't done that way unless they give
a good reason why your way isn't better (note as good isn't good
enough - you always need a good reason to stray from a tested and known
path, and it is often worth putting up with a few minor inconveniences to
stay on it)
Oh - and make sure you can recognise a good reason when you see it ::)

 The guild would like the application builder to learn the
 field.  They would like him to read up on all the literature,
 the analysies.  To emulate the successes and avoid the
 pitfalls of those protocols that went before them.  The
 guild would like the builder to present his protocol and
 hope it be taken seriously.  The guild would like the
 builder of applications to reach acceptable standards.
I would certainly expect a house builder to know how to lay bricks - but
if he insisted on designing the house too, I would expect him to know how
to do that (and not just start putting up walls and hoping it will all
work out later.
Design requires a fair understanding of what you are designing and what
the capabilities and limitations of the materials are - this is why SAs
get paid more than their programming teams (not that I like that given I
am a programmer not a SA).  If you aren't willing to learn how to do that,
you can still follow someone else's design - or take a modular approach
and just drop pre-built units (normally libraries) into those parts of the
code that need them. Libraries can be surprisingly good - if the designer
put in enough effort, they can have sufficient inline M/C for the
timing-critical parts that they are noticably more efficient than
implimenting your own code in a medium or high level language.

 And, the guild would like the builder to take the guild
 seriously, in recognition of the large amounts of time
 guildmembers invest in their knowledge.
That does tend to happen - in any community, you get those who get used to
being authorities, and react badly to being challenged. At least in this
community most of them have the sense to back down when proved wrong :)

 None of that is likely to happen.  The barrier to entry
 into serious cryptographic protocol design is too high
 for the average builder of new applications [2].  He has,
 after all, an application to build.
Indeed so - that is why using a prebuilt standard (or better yet, a
library) as your base is such a good idea. However, a lot of programmers
don't like doing that because
they feel it is either cheating or means all their hard work is going to
be dismissed as just an implimentation of someone else's idea rather
than something original and novel.  However, the odds of someone rolling
their own protocol getting something more efficient or effective as work
that has already been done are low - and if the package you put together
is sufficently good, no users will care it uses SSH (protocol) for comms
or someone else's AES library for 

Re: Monoculture

2003-10-02 Thread Dave Howe
Guus Sliepen [EMAIL PROTECTED] wrote:
 Thor Lancelot Simon wrote:
 In that case, I don't see why you don't bend your efforts towards
 producing an open-source implementation of TLS that doesn't suck.
 We don't want to program another TLS library, we want to create
 a VPN daemon.
And RMS didn't want to write a grep tool/compiler/editor/whatever - he
wanted to write hurd. however, he recognised that hurd needed to be *built
on* a solid foundation of tools and resources; most people have never
heard of hurd, but use directly or indirectly something in the gnu toolbox
every day (mostly without knowing it)
if you build a decent TLS library, then build a VPN daemon to use that
library, you have contributed both a daemon and a TLS library, and
thousands of people may well use the TLS library without needing or
wanting a VPN daemon (given a TLS library is of much more general use than
a vpn daemon)


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Re: Monoculture

2003-10-01 Thread Dave Howe
Jill Ramonsky wrote:
 Is it possible for Bob to instruct his browser to (a) refuse to trust
 anything signed by Eve, and (b) to trust Alice's certificate (which
 she handed to him personally)? (And if so, how?)

 I am very much hoping that you can answer both (a) and (b) with a yes,
ok then yes :)

What it comes down to is a browser will trust any certificate either
a) explicitly marked as trusted or
b) signed by a root CA in its root certificate store

so the correct procedure for (a) is for bob to delete eve's root
certificate from his root store.
for (b) he can either explicitly mark Alice's cert as accepted, or
(technically more interesting) if he trusts her as introducer add her
root cert - which is the same thing if she self-signed her cert - to his
root store, so that *any* cert she signs is accepted.

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Re: why are CAs charging so much for certs anyway? (Re: End of the line for Ireland's dotcom star)

2003-09-25 Thread Dave Howe
Joel Sing wrote:
 Hi Adam,
 I believe they have, at least to a large degree. InstantSSL
 (www.instantssl.com) sell 128-bit certificates for $49USD/annum.
 Certainly far cheaper than the VeriSign or Thawte equivalent. This is
 their 'base' level service which comes with a $50USD warranty, email
 based support and a 30 day refund/reissue policy. One of our clients
 uses one of their certificates and we haven't had an issue with it.
What is their browser coverage like?

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Re: quantum hype

2003-09-21 Thread Dave Howe
 no. its the underlieing hard problem for QC. If there is
 a solution to any of the Hard Problems, nobody knows about them.
right, so it's no better than the arguable hard problem of
factoring a 2048 bit number.
Peter Fairbrother may well be in possession of a break for the QC hard
problem - his last post stated there was a way to clone photons with
high accuracy in retention of their polarization (at the cost of a
irrelevent increase in wavelength) so that Mallory could test photons with
BOTH filters, determining the value of the bit (from the correct filter
which would show a strong bias to the correct bit value) and the
orientation (given the incorrect filter would be roughly 50/50)

 wrong. i don't consider those that shouldn't know about
 some things to be my enemies. i know that crypto is
 useful when someone actively seeks information.
Hmm. normally, the agent attempting to intercept your traffic is termed
the attacker; I don't know many attackers that aren't enemies :)

 but if i want my girlfriend not to see those
 mails i send to this other chick (i have no
 girlfriend btw),
I suspect my wife might not like it if I had one :)

 i encrypt them and guard against the risk that i leave
 the window open when she comes home and she
 accidentally hits enter to read that email.
but not against you accidentally leaving the plaintext window open, or
your system having stored a draft of the plaintext someplace.
endpoint security is typically much, much harder than transmission
security (despite key exchange not being an issue) simply because so many
standard machines and software is orientated towards data loss prevention,
not security.

 i guess it's a matter of definition, so let's just leave it there.
indeed. perhaps interceptor rather than enemy would be closer?

 You seem to have a lot more of a grasp than I.
I am (as usual) standing on the shoulders of giants; I am simply repeating
my understanding of what they said trying to dumb it down to my miserable
level :)

 Anyhow, we are deviating here and there from the topic.
 So let me summarise:
   - QC, if correctly used, can serve as the basis for OTP
encryption.
correct - it is a key negotiation method, not an actual transmission
method.

  - The provable security of QC thus actually comes from OTP.
no, the provable security of OTP is a given. the security of QC comes from
not being able to determine the polarization of a photon without pushing
it though a filter and seeing if it fits :)

  - QC needs an unbroken channel. The channel does not have to be
private because an observer destroys photons, which can be
detected.
destroying photons would mean breaking (diverting the flow of photons
down) the channel, so there is no real distinction.

  - This observer could DoS the communication, but that's akin to
cutting the land-line.
indeed. not only akin, but actually a case of :)

  - Actually, no, because if I don't rely on QC but have other
means, I can switch to another medium if someone cuts my
landline.
in fact, you would be better served using another channel (or channels)
for actual data, and keeping the optical channel for key negotiation only.
a successful MiTM attack relies on controlling *all* the communications
between alice and bob. if there are multiple channels, and even one is
missed, alice and bob can determine there was a middleman involved and the
attack breaks down. Ideal for transmitting the actual data would be (say)
a broadcast medium; alice can check her own trasmissions, and bob can read

 Btw: is this list archived?
yes
http://www.mail-archive.com/cryptography%40metzdowd.com/index.html
and in general terms, always assume mailing lists are not only archived,
but read avidly by the enemies I have and you haven't got ;)

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Re: Pre-cursor to Non-Secret Encryption

2003-06-18 Thread Dave Howe
John Young wrote:
 James Ellis, GCHQ, in his account of the development of non-secret
 encryption credits a Bell Laboratories 1944 report  on Project
 C-43 for stimulating his conception:
However the concept seems familiar enough - unless I am missing something, a
PRNG (n for noise rather than number this time) in sync with a similar PRNG
at the recipient end is mixed with the plaintext signal to give a
cryptotext; the matching unit subtracts the same values from the received
signal to give the original plaintext.  If it were digital we would probably
xor it :)


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Re: An attack on paypal

2003-06-08 Thread Dave Howe
 in a world where there are repeated human mistakes/failures 
 at some point it is recognized that people aren't perfect and the design
 is changed to accommodate peoples foibles. in some respects that is what
 helmets, seat belts, and air bags have been about.

The problem is here, we are blaming the protective device for not being able
to protect against the deliberate use of an attack that bypasses, not
challenges it - by exploiting the gullibility or tendency to take the path
of least resistance of the user.
The real weakness in HTTPS is the tendency of certificates signed by Big
Name CAs to be automagically trusted - even if you have never visited that
site before.  yes, you can fix this almost immediately by untrusting the
root certificate - but then you have to manually verify each and every site
at least once, and possibly every time if you don't mark the cert as
trusted for future reference.
To blame HTTPS for an attack where the user fills in a web form received via
html-rendering email (no https involved at all) is more than a little unfair
though.

 in the past systems have designed long, complicated passwords that are
 hard to remember and must be changed every month. that almost worked when
 a person had to deal with a single shared-secret.
 when it became a fact of life that a person might have tens of such
 different interfaces it became impossible. It wasn't the fault of any
 specific institution, it was a failure of humans being able to deal with
 large numbers of extremely complex, frequently changing passwords.
 Because of known human foibles, it might be a good idea to start shifting
 from an infrastructure with large numbers of shared-secrets to a
 non-shared-secret paradigm.

I am not aware of one (not that that means much, given I am a novice in this
field)
Even PKI relies on something close to a shared secret - a *trustworthy* copy
of the public key, matching a secret copy of the private key. In x509, this
trustworthyness is established by an Ultimately Trusted CA; in pgp, by the
Web Of Trust, in a chain leading back to your own key; in SSH, by your
placing of the public key into your home dir manually (using some other form
of authentication to presumably gain access)
in each of these cases, the private key will almost invariably be protected
by a passphrase; at best, you can have a single passphrase (or even single
private key) to cover all bases.. but that just makes that secret all the
more valuable.

 at a recent cybersecurity conference, somebody made the statement that (of
 the current outsider, internet exploits, approximately 1/3rd are buffer
 overflows, 1/3rd are network traffic containing virus that infects a
 machine because of automatic scripting, and 1/3 are social engineering
 (convince somebody to divulge information). As far as I know, evesdropping
 on network traffic  doesn't even show as a blip on the radar screen.
That is pretty much because defence occupies the position of the interior -
attackers will almost invariably attack weak points, not strong ones. It is
easy to log and calculate how many attacks happen on weak points, but
impossible to calculate how many attacks *would* have happened had the
system not been in place to protect against such attacks, so the attackers
moved onto easier targets.
It makes little sense to try and break one https connection (even at 40 bit)
if by breaking into the server you get that information, hundreds of others
(until discovered) and possibly thousands of others inadvisedly stored
unprotected in a database.

snip
 The types of social engineering attacks then become convincing people to
 insert their hardware token and do really questionable things or mailing
 somebody their existing hardware token along with the valid pin (possibly
 as part of an exchange for replacement). The cost/benefit ratio does start
 to change since there is now much more work on the crooks part for the
 same or less gain. One could also claim that such activities are just part
 of child-proofing the environment (even for adults). On the other hand, it
 could be taken as analogous to designing systems to handle observed
 failure modes (even when the failures are human and not hardware or
 software). Misc. identify theft and credit card fraud reference:

Which again matches well to the Nigerian analogy. Everyone *knows* that
handing over your bank details is a Bad Thing - yet they still do it.


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Re: Maybe It's Snake Oil All the Way Down

2003-06-04 Thread Dave Howe
Bill Frantz wrote:
 I know of one system that takes credit cards over HTTPS, and then
 sends the credit card number, encrypted with GPG to a backend system
 for processing.
For that matter, our system here discards the CC after use (the pre-auth
step with the merchant bank agent gives us back a fulfillment handle that
can only be used to fulfill or cancel that individual transaction - but of
course Amazon *want* to keep your CC details so they can do their
fast-checkout patented thingy.


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