Re: [Cryptography] prism-proof email in the degenerate case

2013-10-10 Thread John Denker
On 10/10/2013 02:20 PM, Ray Dillinger wrote: split the message stream into channels when it gets to be more than, say, 2GB per day. That's fine, in the case where the traffic is heavy. We should also discuss the opposite case: *) If the traffic is light, the servers should generate cover

[Cryptography] heterotic authority + web-of-trust + pinning

2013-09-28 Thread John Denker
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 09/25/2013 04:59 AM, Peter Gutmann wrote: Something that can sign a new RSA-2048 sub-certificate is called a CA. For a browser, it'll have to be a trusted CA. What I was asking you to explain is how the browsers are going to deal with

Re: [Cryptography] real random numbers

2013-09-15 Thread John Denker
Previously I said we need to speak more carefully about these things. Let me start by taking my own advice: Alas on 09/14/2013 12:29 PM, I wrote: a) In the linux random device, /any/ user can mix stuff into the driver's pool. This is a non-privileged operation. The idea is that it can't

Re: [Cryptography] real random numbers

2013-09-13 Thread John Denker
Executive summary: The soundcard on one of my machines runs at 192000 Hz. My beat-up old laptop runs at 96000. An antique server runs at only 48000. There are two channels and several bits of entropy per sample. That's /at least/ a hundred thousand bits per second of real industrial-strength

[Cryptography] auditing a hardware RNG

2013-09-09 Thread John Denker
On 09/05/2013 05:11 PM, Perry E. Metzger wrote: A hardware generator can have horrible flaws that are hard to detect without a lot of data from many devices. Can you be more specific? What flaws? On 09/08/2013 08:42 PM, James A. Donald wrote: It is hard, perhaps impossible, to have test

Re: [Cryptography] tamper-evident crypto?

2013-09-06 Thread John Denker
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 09/05/2013 06:48 PM, Richard Clayton wrote: so you'd probably fail to observe any background activity that tested whether this information was plausible or not and then some chance event would occur that caused someone from Law Enforcement

Re: [Cryptography] tamper-evident crypto? (was: BULLRUN)

2013-09-05 Thread John Denker
I don't have any hard information or even any speculation about BULLRUN, but I have an observation and a question: Traditionally it has been very hard to exploit a break without giving away the fact that you've broken in. So there are two fairly impressive parts to the recent reports: (a)

Re: [Cryptography] Snowden fabricated digital keys to get access to NSA servers?

2013-06-29 Thread John Denker
On 06/28/2013 04:00 PM, John Gilmore wrote: Let's try some speculation about what this phrase, fabricating digital keys, might mean. Here's one hypothesis to consider. a) The so-called digital key was not any sort of decryption key. b) The files were available on the NSA machines in the

Re: Disk encryption advice...

2010-10-08 Thread John Denker
On 10/08/2010 04:27 PM, Perry E. Metzger wrote: I have a client with the following problem. They would like to encrypt all of their Windows workstation drives, but if they do that, the machines require manual intervention to enter a key on every reboot. Why is this a problem? Because

Re: customizing Live CD images

2010-09-10 Thread John Denker
On 08/02/2010 10:47 PM, I wrote: We have been discussing the importance of a unique random-seed file each system. This is important even for systems that boot from read-only media such as CD. To make this somewhat more practical, I have written a script to remix a .iso image so as to add

Re: Randomness, Quantum Mechanics - and Cryptography

2010-09-07 Thread John Denker
On 09/07/2010 10:21 AM, Marsh Ray wrote: If anybody can think of a practical attack against the randomness of a thermal noise source, please let us know. By practical I mean to exclude attacks that use such stupendous resources that it would be far easier to attack other elements of the

Re: Randomness, Quantum Mechanics - and Cryptography

2010-09-07 Thread John Denker
On 09/07/2010 11:19 AM, Perry E. Metzger wrote: 2) You can shield things so as to make this attack very, very difficult. I suspect that for some apps like smart cards that might be hard. OTOH, it might be straightforward to detect the attempt. We should take the belt-and-suspenders

customizing Live CD images (was: urandom etc.)

2010-08-03 Thread John Denker
We have been discussing the importance of a unique random-seed file each system. This is important even forsystems that boot from read-only media such as CD. To make this somewhat more practical, I have written a script to remix a .iso image so as to add one or more last-minute files. The

Re: init.d/urandom : saving random-seed

2010-08-02 Thread John Denker
On 07/31/2010 09:00 PM, Jerry Leichter wrote: I wouldn't recommend this for high-value security, but then if you're dealing with high-value information, there's really no excuse for not having and using a source of true random bits. Yes indeed! On the question of what to do if we can't be

Re: init.d/urandom : saving random-seed

2010-07-31 Thread John Denker
Hi Henrique -- This is to answer the excellent questions you asked at Since that bug is now closed (as it should be), and since these questions are only tangentially related to that bug anyway, I am emailing you directly. Feel free

Re: Persisting /dev/random state across reboots

2010-07-29 Thread John Denker
On 07/29/2010 12:47 PM, Richard Salz wrote: At shutdown, a process copies /dev/random to /var/random-seed which is used on reboots. [1] Actually it typically copies from /dev/urandom not /dev/random, but we agree, the basic idea is to save a seed for use at the next boot-up. Is this a

Re: unattended reboot (was: clouds ...)

2009-08-03 Thread John Denker
On 08/01/2009 02:06 PM, Jerry Leichter wrote: A while back, I evaluated a technology that did it best to solve a basically insoluble problem: How does a server, built on stock technology, keep secrets that it can use to authenticate with other servers after an unattended reboot? This

Re: combining entropy

2008-10-28 Thread John Denker
On 10/28/2008 09:43 AM, Leichter, Jerry wrote: | We start with a group comprising N members (machines or | persons). Each of them, on demand, puts out a 160 bit | word, called a member word. We wish to combine these | to form a single word, the group word, also 160 bits | in length.

Re: combining entropy

2008-10-27 Thread John Denker
On 10/25/2008 04:40 AM, IanG gave us some additional information. Even so, it appears there is still some uncertainty as to interpretation, i.e. some uncertainty as to the requirements and objectives. I hereby propose a new scenario. It is detailed enough to be amenable to formal analysis. The

Re: combining entropy

2008-10-27 Thread John Denker
Alas on 10/25/2008 01:40 PM, I wrote: To summarize: In the special sub-case where M=1, XOR is as good as it gets. In all other cases I can think of, the hash approach is much better. I should have said that in the special sub-case where the member word has entropy density XX=100% _or_ in

Re: combining entropy

2008-10-25 Thread John Denker
On 10/24/2008 03:40 PM, Jack Lloyd wrote: Perhaps our seeming disagreement is due to a differing interpretation of 'trusted'. I took it to mean that at least one pool had a min-entropy above some security bound. You appear to have taken it to mean that it will be uniform random? Thanks, that

Re: combining entropy

2008-10-24 Thread John Denker
On 09/29/2008 05:13 AM, IanG wrote: My assumptions are: * I trust no single source of Random Numbers. * I trust at least one source of all the sources. * no particular difficulty with lossy combination. If I have N pools of entropy (all same size X) and I pool them together with XOR,

Re: combining entropy

2008-10-24 Thread John Denker
On 10/24/2008 01:12 PM, Jack Lloyd wrote: is a very different statement from saying that lacking such an attacker, you can safely assume your 'pools of entropy' (to quote the original question) are independent in the information-theoretic sense. The question, according to the original

Re: Lava lamp random number generator made useful?

2008-09-21 Thread John Denker
On 09/20/2008 12:09 AM, IanG wrote: Does anyone know of a cheap USB random number source? Is $7.59 cheap enough? For that you get a USB audio adapter with mike jack, and then you can run turbid(tm) to produce high-quality randomness.

On randomness

2008-07-31 Thread John Denker
In 1951, John von Neumann wrote: Any one who considers arithmetical methods of producing random digits is, of course, in a state of sin. That may or may not be an overstatement. IMHO it all depends on what is meant by random. The only notion of randomness that I have found worthwhile is the

Re: how to check if your ISP's DNS servers are safe

2008-07-23 Thread John Denker
On 07/23/2008 12:44 AM, Steven M. Bellovin wrote: Niels Provos has a web page up with some javascript that automatically checks if your DNS caching server has been properly patched or not. It is worth telling people to try. Those who

defending against evil in all layers of hardware and software

2008-04-28 Thread John Denker
This is an important discussion The threats are real, and we need to defend against them. We need to consider the _whole_ problem, top to bottom. The layers that could be subverted include, at a minimum: -- The cpu chip itself (which set off the current flurry of interest). -- The boot

customs searching laptops, demanding passwords

2008-02-09 Thread John Denker
I quote from By Ellen Nakashima Washington Post Staff Writer Thursday, February 7, 2008; A01 The seizure of electronics at U.S. borders has prompted protests from travelers who say they now weigh

two-person login?

2008-01-29 Thread John Denker
Hi Folks -- I have been asked to opine on a system that requires a two-person login. Some AIX documents refer to this as a common method of increasing login security However, I don't think it is very common; I get only five hits from

Re: two-person login?

2008-01-29 Thread John Denker
On 01/29/2008 11:34 AM, The Fungi wrote: I don't think it's security theater at all, as long as established procedure backs up this implementation in a sane way. For example, in my professional life, we use this technique for commiting changes to high-priority systems. Procedure is that two

Re: 2008: The year of hack the vote?

2007-12-26 Thread John Denker
On 12/23/2007 08:24 PM, ' =JeffH ' wrote: 2008: The year of hack the vote? Shouldn't that be: 2008: Another year of hack the vote yet again? ..^^^...^ There is every reason to believe that the 2000 presidential election was stolen. A fair/honest/lawful

Re: PunchScan voting protocol

2007-12-15 Thread John Denker
On 12/13/2007 08:23 PM, Taral wrote: On 12/12/07, John Denker [EMAIL PROTECTED] wrote: Several important steps in the process must be carried out in secret, and if there is any leakage, there is unbounded potential for vote-buying and voter coercion. I've done quite a bit of work

PunchScan voting protocol

2007-12-13 Thread John Denker
Hi Folks -- I was wondering to what extent the folks on this list have taken a look the PunchScan voting scheme: The site makes the following claims: End-to-end cryptographic independent verification, or E2E, is a mechanism built into an election that allows voters

electoral security by obscurity on trial

2007-12-06 Thread John Denker
For years, the Election Integrity Committee of the Pima County Democratic Party has been trying to improve the security of the elections systems used in local elections. The results include: -- a dozen or so suggestions that they made were actually accepted and implemented by the county. --

Re: How the Greek cellphone network was tapped.

2007-07-16 Thread John Denker
On 07/10/2007 01:59 AM, Florian Weimer wrote: It's also an open question whether network operators subject to interception requirements can legally offer built-in E2E encryption capabilities without backdoors. I agree. It's a tricky question; see below JI responded: You probably meant

Re: Quantum Cryptography

2007-07-03 Thread John Denker
On 07/01/2007 05:55 AM, Peter Gutmann wrote: One threat model (or at least failure mode) that's always concerned me deeply about QC is that you have absolutely no way of checking whether it's working as required. With any other mechanism you can run test vectors through it, run

Re: Quantum Cryptography

2007-06-26 Thread John Denker
On 06/25/2007 08:23 PM, Greg Troxel wrote: 1) Do you believe the physics? (Most people who know physics seem to.) Well, I do happen to know a thing or two about physics. I know -- there is quite a lot you can do with quantum physics, and -- there is quite a lot you cannot do with quantum

Re: SC-based link encryption

2007-01-05 Thread John Denker
On 01/05/2007 10:53 AM, Paul Hoffman wrote: You could take an IPsec stack and repurpose it down one layer in the stack. At least that way you'll know the security properties of what you create. That is a Good Idea that can be used in a wide range of situations. Here is some additional

Re: gang uses crypto to hide identity theft databases

2006-12-24 Thread John Denker
On 12/22/2006 01:57 PM, Alex Alten wrote: I'm curious as to why the cops didn't just pull the plugs right away. Because that would be a Bad Idea. In a halfway-well-designed system, cutting the power would just do the secret-keepers' job for them. It would probably take a while (minutes,

Re: Impossible compression still not possible. [was RE: Debunking the PGP backdoor myth for good. [was RE: Hypothesis: PGP backdoor (was: A security bug in PGP products?)]]

2006-09-03 Thread John Denker
Dave Korn asked: Is it *necessarily* the case that /any/ polynomial of log N /necessarily/ grows slower than N? Yes. Hint: L'Hôpital's rule. if P(x)==e^(2x) That's not a polynomial. x^Q is a polynomial. Q^x is not. -

Re: Quantum RNG

2006-07-04 Thread John Denker
Andrea Pasquinucci wrote: Quantis is a physical random number generator exploiting an elementary quantum optics process. Photons - light particles - are sent one by one onto a semi-transparent mirror and detected. The exclusive events

Re: Unforgeable Blinded Credentials

2006-04-05 Thread John Denker
Hal Finney wrote in part: ... Attempts to embed sensitive secrets in credentials don't work because there are no sensitive secrets today. You could use credit card numbers or government ID numbers (like US SSN) but in practice such numbers are widely available to the black hat community.

Re: Entropy Definition (was Re: passphrases with more than 160 bits of entropy)

2006-03-26 Thread John Denker
In the context of 0 occurs with probability 1/2 each other number from 1 to 2^{160}+1 happens with probability 2^{-161}. I wrote: This ... serves to illustrate, in an exaggerated way, the necessity of not assuming that the raw data words are IID (independent and identically distributed).

Re: Entropy Definition (was Re: passphrases with more than 160 bits of entropy)

2006-03-24 Thread John Denker
this is clearly a probability distribution (with some technicalities regarding issues of program lengths being glossed over here) as John Denker says. However to go from this to a notion of entropy is more questionable. Not really questionable. If you have a probability, you have an entropy

Re: Entropy Definition (was Re: passphrases with more than 160 bits of entropy)

2006-03-24 Thread John Denker
Ed Gerck wrote: In Physics, Thermodynamics, entropy is a potential [1]. That's true in classical (19th-century) thermodynamics, but not true in modern physics, including statistical mechanics. The existence of superconductors and superfluids removes all doubt about the absolute zero of

Re: Entropy Definition (was Re: passphrases with more than 160 bits of entropy)

2006-03-23 Thread John Denker
Aram Perez wrote: * How do you measure entropy? I was under the (false) impression that Shannon gave a formula that measured the entropy of a message (or information stream). Entropy is defined in terms of probability. It is a measure of how much you don't know about the situation. If by

Re: Entropy Definition (was Re: passphrases with more than 160 bits of entropy)

2006-03-23 Thread John Denker
John Kelsey wrote: As an aside, this whole discussion is confused by the fact that there are a bunch of different domains in which entropy is defined. The algorithmic information theory sense of entropy (how long is the shortest program that produces this sequence?) is miles away from the

Re: Entropy Definition (was Re: passphrases with more than 160 bits of entropy)

2006-03-23 Thread John Denker
I wrote: With some slight fiddling to get the normalization right, 1/2 raised to the power of (program length) defines a probability measure. This may not be the probability you want, but it is a probability, and you can plug it into the entropy definition. John Kelsey wrote: No, this isn't

Re: passphrases with more than 160 bits of entropy

2006-03-22 Thread John Denker
Matt Crawford wrote: I so often get irritated when non-physicists discuss entropy. The word is almost always misused. Yes, the term entropy is often misused ... and we have seen some remarkably wacky misusage in this thread already. However, physicists do not have a monopoly on correct

Re: GnuTLS (libgrypt really) and Postfix

2006-02-15 Thread John Denker
James A. Donald wrote: The correct mechanism is exception handling. Yes, I reckon there is a pretty wide consensus that exceptions provide a satisfactory solution to the sort of problems being discussed in this thread. If caller has provided a mechanism to handle the failure, that mechanism

Re: GnuTLS (libgrypt really) and Postfix

2006-02-13 Thread John Denker
David Wagner wrote: This just shows the dangers of over-generalization. One could make an even stronger statement about the dangers of making assumptions that are not provably correct. Of course, we have to decide which is more important: integrity, or availability. That is a false

Re: thoughts on one time pads

2006-01-31 Thread John Denker
Anne Lynn Wheeler wrote: is there any more reason to destroy a daily key after it as been used than before it has been used? That's quite an amusing turn of phrase. There are two ways to interpret it: *) If taken literally, the idea of destroying a key _before_ it is used is truly an

Re: thoughts on one time pads

2006-01-31 Thread John Denker
I forgot to mention in my previous message: It is worth your time to read _Between Silk and Cyanide_. That contains an example of somebody who thought really hard about what his threat was, and came up with a system to deal with the threat ... a system that ran counter to the previous

Re: thoughts on one time pads

2006-01-27 Thread John Denker
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. There are various versions of getting rid of a disk file. 1) Deletion: Throwing away the pointer and putting the blocks back on the free

Re: permutations +- groups

2005-12-22 Thread John Denker
Ben Laurie wrote: Good ciphers aren't permutations, though, are they? Because if they were, they'd be groups, and that would be bad. There are multiple misconceptions rolled together there. 1) All of the common block ciphers (good and otherwise) are permutations. To prove this, it suffices

packet traffic analysis

2005-10-31 Thread John Denker
Travis H. wrote: Part of the problem is using a packet-switched network; if we had circuit-based, then thwarting traffic analysis is easy; you just fill the link with random garbage when not transmitting packets. OK so far ... There are two problems with this; one, getting enough

Re: packet traffic analysis

2005-10-31 Thread John Denker
In the context of: If your plaintext consists primarily of small packets, you should set the MTU of the transporter to be small. This will cause fragmentation of the large packets, which is the price you have to pay. Conversely, if your plaintext consists primarily of large packets, you

Re: EDP (entropy distribution protocol), userland PRNG design

2005-10-24 Thread John Denker
I've been following this thread for a couple of weeks now, and so far virtually none of it makes any sense to me. Back on 10/12/2005 Travis H. wrote: I am thinking of making a userland entropy distribution system, so that expensive HWRNGs may be shared securely amongst several machines. What

continuity of identity

2005-09-27 Thread John Denker
Jerrold Leichter mentioned that: a self- signed cert is better than no cert at all: At least it can be used in an SSH-like continuity of identity scheme. I agree there is considerable merit to a continuity of identity scheme. But there are ways the idea can be improved. So let's discuss

Re: Clearing sensitive in-memory data in perl

2005-09-17 Thread John Denker
Victor Duchovni wrote: So wouldn't the world be a better place if we could all agree on a single such library? Or at least, a single API. Like the STL is for C++. Yes, absolutely, but who is going to do it? One could argue it has already been done. There exists a widely available,

Re: solving the wrong problem

2005-08-07 Thread John Denker
Adam Shostack wrote: Here's a thought: Putting up a beware of dog sign, instead of getting a dog. That's an interesting topic for discussion, but I don't think it answers Perry's original question, because there are plenty of situations where the semblence of protection is actually a

Re: solving the wrong problem

2005-08-06 Thread John Denker
Perry E. Metzger wrote: We need a term for this sort of thing -- the steel tamper resistant lock added to the tissue paper door on the wrong vault entirely, at great expense, by a brilliant mind that does not understand the underlying threat model at all. Anyone have a good phrase in mind that

Re: ID theft -- so what?

2005-07-13 Thread John Denker
On 07/13/05 12:15, Perry E. Metzger wrote: However, I would like to make one small subtle point. ... the use of widely known pieces of information about someone to identify them. Yes, there are annoying terminology issues here. In the _Handbook of Applied Cryptography_ (_HAC_) -- on page

ID theft -- so what?

2005-07-12 Thread John Denker
I am reminded of a passage from Buffy the Vampire Slayer. In the episode Lie to Me: BILLY FORDHAM: I know who you are. SPIKE: I know who I am, too. So what? My point here is that knowing who I am shouldn't be a crime, nor should it contribute to enabling any crime. Suppose you

Re: WYTM - but what if it was true?

2005-06-27 Thread John Denker
On 06/27/05 00:28, Dan Kaminsky wrote: ... there exists an acceptable solution that keeps PC's with persistent stores secure. A bootable CD from a bank is an unexpectedly compelling option Even more compelling is: -- obtain laptop hardware from a trusted source -- obtain software from a

Re: Entropy and PRNGs

2005-01-26 Thread John Denker
Ed Gerck wrote: Let me comment, John, that thermal noise is not random When did you figure that out? If you'd been paying attention, you'd know that I figured that out a long time ago. First of all, the phrase not random is ambiguous. I said Some people think random should denote 100% entropy

Re: Entropy and PRNGs

2005-01-10 Thread John Denker
Referring to I wrote: I just took a look at the first couple of pages. IMHO it has much room for improvement. David Wagner responded: I guess I have to take exception. I disagree. I think Ben Laurie's paper is quite good. I thought your criticisms missed

Re: Entropy and PRNGs

2005-01-10 Thread John Denker
Ben Laurie wrote: The point I am trying to make is that predictability is in the eye of the beholder. I think it is unpredictable, my attacker does not. I still cannot see how that can happen to anyone unless they're being willfully stupid. It's like something out of Mad Magazine: White Spy

Re: Entropy and PRNGs

2005-01-10 Thread John Denker
John Kelsey wrote: If your attacker (who lives sometime in the future, and may have a large budget besides) comes up with a better model to describe the process you're using as a source of noise, you could be out of luck. The thing that matters is H(X| all information available to the attacker),

Re: entropy depletion

2005-01-08 Thread John Denker
Zooko O'Whielacronx wrote: I would love to have an information-theoretic argument for the security of my PRNG, but that's not what we have, Yes, and I'd like my goldfish to ride a bicycle, but he can't. The P in PRNG is for Pseudo, and means the PRNG is relying on computational intractability,

Re: entropy depletion

2005-01-07 Thread John Denker
Jerrold Leichter asked: random number generator this way. Just what *is* good enough? That's a good question. I think there is a good answer. It sheds light on the distinction of pseudorandomness versus entropy: A long string produced by a good PRNG is conditionally compressible

Re: entropy depletion

2005-01-07 Thread John Denker
I wrote: A long string produced by a good PRNG is conditionally compressible in the sense that we know there exists a shorter representation, but at the same time we believe it to be conditionally incompressible in the sense that the adversaries have no feasible way of finding a shorter

Re: entropy depletion

2005-01-06 Thread John Denker
I wrote: Taking bits out of the PRNG *does* reduce its entropy. Enzo Michelangeli wrote: By how much exactly? By one bit per bit. I'd say, _under the hypothesis that the one-way function can't be broken and other attacks fail_, exactly zero; in the real world, maybe a little more. If you said

Re: SSL/TLS passive sniffing

2005-01-04 Thread John Denker
I wrote: If the problem is a shortage of random bits, get more random bits! Florian Weimer responded: We are talking about a stream of several kilobits per second on a busy server (with suitable mailing lists, of course). This is impossible to obtain without special hardware. Not very special, as

Re: SSL/TLS passive sniffing

2004-12-22 Thread John Denker
Florian Weimer wrote: Would you recommend to switch to /dev/urandom (which doesn't block if the entropy estimate for the in-kernel pool reaches 0), and stick to generating new DH parameters for each connection, No, I wouldn't. or ... generate them once per day and use it for several connections?

Re: IPsec +- Perfect Forward Secrecy

2004-12-05 Thread John Denker
OK, let me ask a more specific question. Actually, let me put forth some hypotheses about how I think it works, and see if anyone has corrections or comments. 0) I'm not sure the words Perfect Forward Secrecy convey what we mean when we talk about PFS. Definition 12.16 in HAC suggests

Re: Compression theory reference?

2004-09-06 Thread John Denker
Matt Crawford wrote: Plus a string of log(N) bits telling you how many times to apply the decompression function! Uh-oh, now goes over the judge's head ... Hadmut Danisch wrote: The problem is that if you ask for a string of log(N) bits, then someone else could take this as a proof that this

Re: Compression theory reference?

2004-09-01 Thread John Denker
I wrote: 4) Don't forget the _recursion_ argument. Take their favorite algorithm (call it XX). If their claims are correct, XX should be able to compress _anything_. That is, the output of XX should _always_ be at least one bit shorter than the input. Then the compound operation XX(XX(...))

Re: ?splints for broken hash functions

2004-09-01 Thread John Denker
I wrote the Bi are the input blocks: (IV) - B1 - B2 - B3 - ... Bk - H1 (IV) - B2 - B3 - ... Bk - B1 - H2 then we combine H1 and H2 nonlinearly. (Note that I have since proposed a couple of improvements, but I don't think they are relevant to the present remarks.) David Wagner wrote: This

Re: ?splints for broken hash functions

2004-08-31 Thread John Denker
Jerry Leichter writes: However ... *any* on-line algorithm falls to a Joux-style attack. Hal Finney wrote: ... hashes that support incremental hashing, as any useful hash surely must, If you insist on being able to hash exceedingly long strings (i.e. longer than your storage capacity) here is a

Re: ?splints for broken hash functions

2004-08-31 Thread John Denker
I agree with 99% of what Hal Finney wrote. I won't repeat the parts we agree on. But let's discuss these parts: how much harder? Well, probably a lot. Finding a regular B2 collision in a perfect 160 bit hash compression function takes 2^80 work. Finding a double collision like this is

Re: Compression theory reference?

2004-08-31 Thread John Denker
Hadmut Danisch wrote: It can be easily shown that there is no lossless compression method which can effectively compress every possible input. OK. ... I need a book about computer science or encoding theory, which explicitely says that this is impossible, in a way that a person unexperienced in

Re: First quantum crypto bank transfer

2004-08-24 Thread John Denker
Jerrold Leichter wrote: ... the comments I've seen on this list and elsewhere have been much broader, and amount to QM secure bit distribution is dumb, it solves no problem we haven't already solved better with classical techniques. Most of the comments on this list are more nuanced than that.

The Call Is Cheap. The Wiretap Is Extra

2004-08-24 Thread John Denker
1) Here's an article from the New York Times. The headline just about says it all. Reportedly THEY want voice-over-internet users to pay for the privilege of having their calls tapped. The Call Is Cheap. The Wiretap Is Extra.

Al Qaeda crypto reportedly fails the test

2004-08-02 Thread John Denker
News article says in part: The BBC's Zaffar Abbas, in Islamabad, says it appears that US investigators were able to unscramble information on the computers after Pakistan passed on suspicious encrypted documents.

Re: Using crypto against Phishing, Spoofing and Spamming...

2004-07-18 Thread John Denker
Enzo Michelangeli wrote: Can someone explain me how the phishermen escape identification and prosecution? Gaining online access to someone's account allows, at most, to execute wire transfers to other bank accounts: but in these days anonymous accounts are not exactly easy to get in any country,

Re: Humorous anti-SSL PR

2004-07-15 Thread John Denker
J Harper [EMAIL PROTECTED] wrote: This barely deserves mention, but is worth it for the humor: Information Security Expert says SSL (Secure Socket Layer) is Nothing More Than a Condom that Just Protects the Pipe To which Eric Rescorla replied:

Re: Hyperencryption by virtual satellite

2004-07-11 Thread John Denker
Way back on 05/20/2004 Ivan Krstic wrote: Michael O. Rabin lectures on hyper-encryption and provably everlasting secrets. ... View here: To my surprise, there has been no follow-up discussion on this list. (Hint: Most people on this list will want to

Re: authentication and authorization (was: Question on the state of the security industry)

2004-07-01 Thread John Denker
Ian Grigg wrote: The phishing thing has now reached the mainstream, epidemic proportions that were feared and predicted in this list over the last year or two. OK. For the first time we are facing a real, difficult security problem. And the security experts have shot their wad. The object

Re: TIA Offices Discovered

2004-06-10 Thread John Denker
R. A. Hettinga wrote: From: Tefft, Bruce [EMAIL PROTECTED] ... Where Big Brother Snoops on Americans 24/7 By TERESA HAMPTON DOUG THOMPSON ... Although employees who work in the building are supposed to keep their presence there a secret, they regularly sport their DARPA id badges around their

stego in the wild: bomb-making CDs

2003-12-28 Thread John Denker
] Thursday 25 December 2003, 17:13 Makka Time, 14:13 GMT ] ] Saudis swoop on DIY bomb guide ] ] Authorities in the kingdom have arrested five people after ] raiding computer shops selling compact disks containing ] hidden bomb-making instructions, a local newspaper reported ] on Thursday. ] ]