Cryptography-Digest Digest #381, Volume #14 Fri, 18 May 01 13:13:00 EDT
Contents:
Re: Help working through RSA example in Applied Cryptography 2nd edition p. 468
(John Savard)
Re: Questionable security measures (CIC and Cloakware!) ("Tom St Denis")
Re: People with x86 cpus (please reply) ("Tom St Denis")
truth+integrity=sore losers ("Tom St Denis")
Re: People with x86 cpus (please reply) (Rainer Nausedat)
Employing multiple algorithms (Mok-Kong Shen)
Re: taking your PC in for repair? WARNING: What will they find? ("Cernunnus")
Re: Questionable security measures (CIC and Cloakware!) (Mok-Kong Shen)
Re: People with x86 cpus (please reply) ("Tom St Denis")
Re: Questionable security measures (CIC and Cloakware!) ("Tom St Denis")
Re: Questionable security measures (CIC and Cloakware!) (nemo outis)
Re: taking your PC in for repair? WARNING: What will they find? (Who Dat ?)
Re: Questionable security measures (CIC and Cloakware!) ("Tom St Denis")
Re: OT - Questionable security measures (CIC and Cloakware!) (Jeffrey Williams)
Re: Choosing algorithms (jlcooke)
Re: Truncation (jlcooke)
Re: Questionable security measures (Cloakware!) ("AY")
Re: Questionable security measures (Cloakware!) ("Tom St Denis")
Re: OT - Questionable security measures (CIC and Cloakware!) ("Tom St Denis")
Re: PGP details (jlcooke)
----------------------------------------------------------------------------
From: [EMAIL PROTECTED] (John Savard)
Subject: Re: Help working through RSA example in Applied Cryptography 2nd edition p.
468
Date: Fri, 18 May 2001 15:14:04 GMT
On Fri, 18 May 2001 00:54:02 GMT, [EMAIL PROTECTED]
(Beatlebum) wrote, in part:
>I'm stumped by the line that reads:
>d = 79^-1 mod 3220 = 1019
>Obviously I'm reading the notation wrong, but 79^-1 is 0.0126...,
>how the heck does 1019 come out of this?
No, you don't really have the notation wrong, it's the concept of
reciprocals in modular arithmetic which you have wrong.
79 times some integer will equal 1 modulo 3220. That integer, which
will be between 2 and 3219, is what is wanted.
John Savard
http://home.ecn.ab.ca/~jsavard/frhome.htm
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: Questionable security measures (CIC and Cloakware!)
Date: Fri, 18 May 2001 15:15:25 GMT
"Mok-Kong Shen" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
>
>
> Tom St Denis wrote:
> >
>
> > I haven't broken any agreement. My contract with Cloakware doesn't say
"you
> > must speak positive about the company at all times". It may sound
corny
> > but I really want to be a person (have to be PC nowadays...) of science
and
> > this sorta of work while it is scientific does not follow any of the
> > principles I wish to follow myself. They want to release stuff
irregardless
> > of how much analysis they have/have not done. By "just cashing a
paycheque"
> > I am demeaning the whole value of scientific research...
>
> Consciously demolishing a firm's reputation or the like
> is definitely a solid ground for discharge. I have no wonder
> of your current thinking, since that's probably your very
> first job in life. If you thoughts are in conflict with the
> policy or moral or the like of a company with which you
> have a contract to work and feel uncomfortable and you are
> not on the top level of the management of the company, the
> only decent and sensible way I am aware of is to voluntarily
> quit. A commercial organization is inherently different
> from the society of common people at large of democratic
> countries, where everybody has a right to express his
> free opinions. Thus we can here in the group criticize
> export regulations, Wassenaar, RIPA, etc. etc. and that
> presumably has contributed somewhat in these matters.
> But even a government officer may not, in his official
> position, deliberately speak negatively in the public
> about what the government has done, except in rather
> special cases where he has obtained the permission to
> do so from his superior.
I did not lie.
I did not violate my contract or NDA.
What did I do wrong? Posting truth is a crime now?
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: People with x86 cpus (please reply)
Date: Fri, 18 May 2001 15:15:35 GMT
"Christian Schwarz" <[EMAIL PROTECTED]> wrote in message
news:9e37bk$8ut$04$[EMAIL PROTECTED]...
> pentium mmx: 240 cycles
> pentium 3 (no coppermine): 200 cycles
Thanks,
Tom
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: truth+integrity=sore losers
Date: Fri, 18 May 2001 15:20:56 GMT
Well folks you were right, what a way to learn a lesson. I got canned from
Cloakware today.
They had no official reason for firing me except to say "if you don't know
what you did wrong you shouldn't be here".
So from what I gather "truth+integrity=sore losers_is congruent to_can the
employee".
What exactly did I do wrong? I didn't lie, I didn't violate my NDA....
--
Tom St Denis
---
http://tomstdenis.home.dhs.org
------------------------------
From: Rainer Nausedat <[EMAIL PROTECTED]>
Subject: Re: People with x86 cpus (please reply)
Date: Fri, 18 May 2001 17:31:20 +0200
In article <DA7N6.125755$[EMAIL PROTECTED]>,
[EMAIL PROTECTED] says...
> - Amd K6, K6-II, K7 (original not T-bird)
Amd K6-II 222 cycles
Amd K6 224 cycles
------------------------------
From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Employing multiple algorithms
Date: Fri, 18 May 2001 17:31:55 +0200
The following is inspired by (in fact essentially repeating)
some discussion stuffs (by Bo Dömstedt and others as well as
myself) in some previous threads of the group.
Let there be m block ciphers of the same size, each being
instantiated with a number of keys (these keys may be
constant or dynamically changing in some way), thus
resulting in n (>> m) differing encryption schemes that can
be arbitrarily chosen for encryption of any given block of
input. We employ a PRNG with a secret seed to do the
decision of dynamically selecting the n schemes. If desired,
the result of processing of any block of input can be used
as feedback to influence the state of the PRNG and hence its
future output. Further, the PRNG may also arbitrarily decide
to use more than one scheme to multiple-encrypt any given
block of input in any order.
This is evidently rather expensive and is sort of a mammoth
machinery. One would certainly not use it, if any of the
block ciphers with a single key is deemed already secure
enough for one's applications. On the other hand, the system
is fairly versatile. It permits the use of arbitrary amounts
of key materials and, since the PRNG is only (very)
indirectly involved in producing the ciphertext, it seems
plausible that the chance of predicting its output and hence
cracking the system thereby is very remote.
M. K. Shen
===========================
http://home.t-online.de/home/mok-kong.shen
------------------------------
From: "Cernunnus" <[EMAIL PROTECTED]>
Crossposted-To:
alt.privacy,alt.security.pgp,alt.security.scramdisk,alt.privacy.anon-server
Subject: Re: taking your PC in for repair? WARNING: What will they find?
Date: Fri, 18 May 2001 10:45:44 -0500
> >>
> >> It can defeat even the tools used by the US Secret Service, and the
> >> USA Customs Service and LAPD.
> >
> >Wrong. Data can be recovered after using this product.
>
> Where is your proof? Please provide proof that Evidence Eliminator does
not
> perform as advertised.
>
> Visit our website and see for yourself that E.E. does what we claim
> and a whole lot more.
>
> http://www.evidence-eliminator.pyar.com
>
>
Where is *your proof*? Visited your site. Saw no proof, just propaganda.
--
[EMAIL PROTECTED] (remove the goddess to reply)
The most incomprehensible thing about
the world is that it is at all comprehensible.
--Albert Einstein--
------------------------------
From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: Questionable security measures (CIC and Cloakware!)
Date: Fri, 18 May 2001 17:46:29 +0200
Tom St Denis wrote:
>
> I did not lie.
> I did not violate my contract or NDA.
>
> What did I do wrong? Posting truth is a crime now?
I said that your employer may be exceptionally liberal.
On the other hand, there is certain written or otherwise
commonly accepted norms of conduct for employers of a
commercial company. There is nothing very special about
that. Even in private life, there are such norms. If
I am invited to dinner by someone and the dishes are
not of my preference, I don't start to give critiques
but instead may decline a future invitation by the
same host. One doesn't always speak out the truth.
Besides, in many cases the truth is simply undecidable
or unknowable. (What one believes to be the truth
might turn out to be an illusion.)
M. K. Shen
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: People with x86 cpus (please reply)
Date: Fri, 18 May 2001 15:57:13 GMT
"Rainer Nausedat" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> In article <DA7N6.125755$[EMAIL PROTECTED]>,
> [EMAIL PROTECTED] says...
> > - Amd K6, K6-II, K7 (original not T-bird)
>
> Amd K6-II 222 cycles
>
> Amd K6 224 cycles
Thanks, so far it seems this cipher is under 256 cycles per block on all
platforms... not bad..It's faster than Twofish :-) (now only to see if it's
even remotely secure)...
Tom
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: Questionable security measures (CIC and Cloakware!)
Date: Fri, 18 May 2001 15:58:21 GMT
"Mok-Kong Shen" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
>
>
> Tom St Denis wrote:
> >
> > I did not lie.
> > I did not violate my contract or NDA.
> >
> > What did I do wrong? Posting truth is a crime now?
>
> I said that your employer may be exceptionally liberal.
Well they are not.
> On the other hand, there is certain written or otherwise
> commonly accepted norms of conduct for employers of a
> commercial company. There is nothing very special about
> that. Even in private life, there are such norms. If
> I am invited to dinner by someone and the dishes are
> not of my preference, I don't start to give critiques
> but instead may decline a future invitation by the
> same host. One doesn't always speak out the truth.
> Besides, in many cases the truth is simply undecidable
> or unknowable. (What one believes to be the truth
> might turn out to be an illusion.)
If you worked for a drug company that made cyanide asprin would you just ho
hum as millions died?
Tom
------------------------------
From: [EMAIL PROTECTED] (nemo outis)
Subject: Re: Questionable security measures (CIC and Cloakware!)
Date: Fri, 18 May 2001 16:02:42 GMT
In article <h0bN6.126033$[EMAIL PROTECTED]>, "Tom St Denis"
<[EMAIL PROTECTED]> wrote:
..long snip...
>
>I did not lie.
>I did not violate my contract or NDA.
>
>What did I do wrong? Posting truth is a crime now?
>
First of all I applaud your decision to put morality and professionalism (as
you see them) at a higher priority than commercial or career objectives.
However, I believe that you could better achieve your objectives if you
leavened that youthful righteousness with a bit of tact and discretion. And
you can certainly do that without selling out your values.
It is a near-invariable commercial practice that you owe a duty of care to
your employer's (or client's, if you are a contractor) interests (and it's not
solely up to you to be the judge of where the employer's interests do, or
should, lie). Most courts will agree with this, and will "read in" implicit
clauses in your contract (whether oral or written) to this effect. That duty
will generally include not "bad-mouthing" the employer *even if what you say
is true.* This principle may be overridden in certain cases, such as
compelling public interest or exercise of free speech, but even then you are
not on completely solid ground. Breach of this duty of care is grounds for
disciplinary action, possibly up to and including dismissal for cause, and may
even open an avenue for a suit for damages.
Clarifying when public duty (either to the general public or a
company's customers) overrides private duty to an employer has led to
whistle-blowing legislation in some jurisdictions. This is because, in the
absence of such legislation, the private duty has generally been found to be
very far-ranging and only breachable in exceptional circumstances. Where to
strike the balance is a thorny problem, but there is no doubt that there
should be a "balancing" test. It is a fact of commercial life that the
current balance leans fairly strongly towards the employer's interests but is
steadily moving away from it. That process has come about from social
pressures (pushed by people with sentiments similar to yours) and has brought
about product liability and other changes. You may regard the current
situation as a genuine "social consensus" or a shameful protective wall for
shoddy practices. But if you want to be a social pioneer, remember that
pioneers often get stuck with arrows :-)
As a practical matter, you have a decision of whether to work from within,
work publicly, just quit, tattle to clients, become a shareholder activist,
etc. Contrary to some others, I do not believe that you must shut up and toe
the party line or get out. And for sure, I wouldn't want to work for a
company that stifled genuine discussion and debate (although I could
understand the company also not wanting to air its dirty linen in public).
Striking the right balance is a matter for judgment, and that is an even rarer
commodity than moral probity.
Regards,
------------------------------
From: Who Dat ? <?????@?????>
Crossposted-To:
alt.privacy,alt.security.pgp,alt.security.scramdisk,alt.privacy.anon-server
Subject: Re: taking your PC in for repair? WARNING: What will they find?
Date: Fri, 18 May 2001 12:02:42 -0400
On Fri, 18 May 2001 10:45:44 -0500 "Cernunnus" <[EMAIL PROTECTED]>
wrote:
>
>> >>
>> >> It can defeat even the tools used by the US Secret Service, and the
>> >> USA Customs Service and LAPD.
>> >
>> >Wrong. Data can be recovered after using this product.
>>
>> Where is your proof? Please provide proof that Evidence Eliminator does
>not
>> perform as advertised.
>>
>> Visit our website and see for yourself that E.E. does what we claim
>> and a whole lot more.
>>
>> http://www.evidence-eliminator.pyar.com
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>Where is *your proof*? Visited your site.
<nudge> Better visit that site again ;)
>Saw no proof, just propaganda.
Well, you'll get no argument from me on that point.
--
*********** UPDATED!********************
E.E. authors come clean on their product!
http://www.evidence-eliminator.pyar.com
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: Questionable security measures (CIC and Cloakware!)
Date: Fri, 18 May 2001 16:14:27 GMT
"nemo outis" <[EMAIL PROTECTED]> wrote in message
news:CIbN6.10735$[EMAIL PROTECTED]...
> In article <h0bN6.126033$[EMAIL PROTECTED]>, "Tom St
Denis" <[EMAIL PROTECTED]> wrote:
> ..long snip...
> >
> >I did not lie.
> >I did not violate my contract or NDA.
> >
> >What did I do wrong? Posting truth is a crime now?
> >
>
>
> First of all I applaud your decision to put morality and professionalism
(as
> you see them) at a higher priority than commercial or career objectives.
Thank you.
> However, I believe that you could better achieve your objectives if you
> leavened that youthful righteousness with a bit of tact and discretion.
And
> you can certainly do that without selling out your values.
How so? They have no interest in researching their products openly. It is
a rerun of all the cell phones, dvd, etc. All done in closed doors. I
wanted to get info so I could analyze it and I think customers would be
happier if they knew 100,000s of people have seen it and no breaks yet.
That's my thoughts... could be wrong.
> It is a near-invariable commercial practice that you owe a duty of care to
> your employer's (or client's, if you are a contractor) interests (and it's
not
> solely up to you to be the judge of where the employer's interests do, or
> should, lie). Most courts will agree with this, and will "read in"
implicit
> clauses in your contract (whether oral or written) to this effect. That
duty
> will generally include not "bad-mouthing" the employer *even if what you
say
> is true.* This principle may be overridden in certain cases, such as
> compelling public interest or exercise of free speech, but even then you
are
> not on completely solid ground. Breach of this duty of care is grounds
for
> disciplinary action, possibly up to and including dismissal for cause, and
may
> even open an avenue for a suit for damages.
I don't see grounds for this. I didn't lie so right away the faults I found
must be true. Second the information I released was not private so anyone
else could have found it (be honest, have you ever heard of Cloakware before
today?).
I could see if I lied and said All their products suck and they are idiots.
But I didn't. I simply stated that closed door security analysis is
shameful, which is an opionion they cannot withhold.
> Clarifying when public duty (either to the general public or a
> company's customers) overrides private duty to an employer has led to
> whistle-blowing legislation in some jurisdictions. This is because, in
the
> absence of such legislation, the private duty has generally been found to
be
> very far-ranging and only breachable in exceptional circumstances. Where
to
> strike the balance is a thorny problem, but there is no doubt that there
> should be a "balancing" test. It is a fact of commercial life that the
> current balance leans fairly strongly towards the employer's interests but
is
> steadily moving away from it. That process has come about from social
> pressures (pushed by people with sentiments similar to yours) and has
brought
> about product liability and other changes. You may regard the current
> situation as a genuine "social consensus" or a shameful protective wall
for
> shoddy practices. But if you want to be a social pioneer, remember that
> pioneers often get stuck with arrows :-)
Someone has to start being honest. Geez. If I can get canned for telling
the truth think of what else they can do. Of course I have grounds to sue
for wrongful termination. I won't because I am in school and don't have
time for this.
Speaking of which if anyone has an internship placement (just a few hours a
week say 20) I would love to hear from ya (if you're in the Kanata/Ottawa
area). Just keep in mind I do honour NDA's and I don't publicly lie about
companies. I can be trusted! I've worked at several other places (not in
computers) before and performed well.
> As a practical matter, you have a decision of whether to work from within,
> work publicly, just quit, tattle to clients, become a shareholder
activist,
> etc. Contrary to some others, I do not believe that you must shut up and
toe
> the party line or get out. And for sure, I wouldn't want to work for a
> company that stifled genuine discussion and debate (although I could
> understand the company also not wanting to air its dirty linen in public).
>
> Striking the right balance is a matter for judgment, and that is an even
rarer
> commodity than moral probity.
Well I want to be a person who believes in the principles of science. That
job really got in the way. From my experience alot of cryptographic ideas
(not mentioning anything in particular) I came accross were smart and
intelligent but not entirely thought through in terms of "if an attacker did
this...". Mainly they wanted the upper not lower bound on security. In
terms of real life security often we live by the lower bound just to be
safe. They don't. I will be the first to admit they are smart intelligent
people. They just are not cryptographers and don't think like attackers
afaik. (of course this is all just my thoughts on the matter so don't take
this last bit as a 100% truth...)
Tom
------------------------------
From: Jeffrey Williams <[EMAIL PROTECTED]>
Subject: Re: OT - Questionable security measures (CIC and Cloakware!)
Date: Fri, 18 May 2001 11:21:27 -0500
Certainly not.
But that is not a good analogy for this situation. This is more along the
lines of you working for a drug company which won't let you into the production
floor to see exactly how they are making aspirin. You may be right: they may
be using cyanide. But, then again, you may be wrong. You simply don't know.
Stanley Chow posted a well-written, rational post. You ought to have a chat
with him (actually, you ought to have done so before your initial post). If
you cannot believe, or trust, him in terms of the contents of his post, you
probably ought to look for a new job.
I think, in this case, you are in the wrong. Had you not identified yourself
as an employee of Cloakware, then it might reasonably be a freedom of speech
issue. As soon as you identified yourself as an employee, you stepped onto
thin ice. Most employers have a reasonable expectation that their employees
will uphold the reputation of the company.
Jeff
Tom St Denis wrote:
<snip>
> If you worked for a drug company that made cyanide asprin would you just ho
> hum as millions died?
>
> Tom
------------------------------
From: jlcooke <[EMAIL PROTECTED]>
Subject: Re: Choosing algorithms
Date: 18 May 2001 16:13:41 GMT
So do you trust any hashes less than 256-bits?
You have a D-bit hash H(x) you trust, you set the stepping size to
S-bytes and you're hashing a F-bytes of data.
H''(x) is defined by the following:
1. both H0 and H1 are initialized.
2. CARRY is initialized to some standard value SV
3. S-bytes of input (x0) is processed by H0:
H0(CARRY cat x0)
CARRY = final_digest(H0)
4. S-byte more is input (x1) is processed by H1:
H1(CARRY cat x1)
CARRY = final_digest(H1)
5. goto 3
...
if the final digest D'' is requested from H''(x),
D0 = final_digest(H0) // may be in CARRY already
D1 = final_digest(H0) // may be in CARRY already
D'' = (D0 cat D1)
This chains each stepping of the F-byte file to the previous step. The
final two digests (D0 and D1 and so D'') depend on all previous bytes.
A little easier to see:
H1(H0(H1(H0(SV cat x0) cat x1) cat x2) cat x3)
D'' = (final_digest(H0) cat final_digest(H1))
I'm sure there are standards out there for doubling the output of a
digest function. I've never never seen a use for them personally.
JLC
"Panu Hämäläinen" wrote:
>
> Hi!
>
> I was just wondering following.
>
> Suppose a communications system requiring highly reliable security design.
> Which would be the number 1 choices of the available algorithms for
>
> 1. public-key encryption
> 2. secret-key encryption (and encryption mode)
> 3. hash calculation
> 4. digital signing
> 5. MAC calculation
>
> Suggestions...
>
> -- Panu Hämäläinen
------------------------------
From: jlcooke <[EMAIL PROTECTED]>
Subject: Re: Truncation
Date: 18 May 2001 16:16:08 GMT
Details on the T(x) are needed for that.
JLC
Charles Nicol wrote:
>
> Consider the truncation function T.
> In general T((a+1)/a)^(m+n)) is not equal to T((a+1)/a)^m)*T((a+1)/a)^n)
> where a is a positive integer.
> However if a is large then there is equality of these terms.For example if
> a=1000,then equality holds for all m and n such that m+n<693.
> Is it possible to obtain a bound B such that equality does hold for all m
> and n such that m+n<B for given a?
------------------------------
From: "AY" <[EMAIL PROTECTED]>
Subject: Re: Questionable security measures (Cloakware!)
Date: Fri, 18 May 2001 17:27:09 +0100
>It seems this incident
>grew out of the fact that I didn't let Tom see the source code
>when he asked me.
Has he just got fired for asking for the source code? What exactly are the
grounds for his dismissal?
<Quoting from Tom>
They had no official reason for firing me except to say "if you don't know
what you did wrong you shouldn't be here".
</Quote>
Is that really the case? Is that an accepted reason for dismissal in Canada?
I would think Tom has the best intentions to help you develop a good and
secure product. If he got sacked just because you got p****d off with him
then I think both of you lose out. How much have Tom posts damaged your
company? To me, a Palm user, his dismissal means that I won't ever buy your
product. You (or whoever fired him) did the damage to your company.
I really wish to see some reconciliation here, perhaps from both parties.
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: Questionable security measures (Cloakware!)
Date: Fri, 18 May 2001 16:25:39 GMT
"AY" <[EMAIL PROTECTED]> wrote in message
news:9e3i46$f8f$[EMAIL PROTECTED]...
>
> >It seems this incident
> >grew out of the fact that I didn't let Tom see the source code
> >when he asked me.
>
>
> Has he just got fired for asking for the source code? What exactly are the
> grounds for his dismissal?
>
> <Quoting from Tom>
> They had no official reason for firing me except to say "if you don't know
> what you did wrong you shouldn't be here".
> </Quote>
>
> Is that really the case? Is that an accepted reason for dismissal in
Canada?
>
> I would think Tom has the best intentions to help you develop a good and
> secure product. If he got sacked just because you got p****d off with him
> then I think both of you lose out. How much have Tom posts damaged your
> company? To me, a Palm user, his dismissal means that I won't ever buy
your
> product. You (or whoever fired him) did the damage to your company.
>
> I really wish to see some reconciliation here, perhaps from both parties.
See I wouldn't go this far. For all I know the product is perfectly secure.
But how do we know? They won't release the information to cryptographers.
Personally I got sacked because I pointed out a huge business flaw...
Tom
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: OT - Questionable security measures (CIC and Cloakware!)
Date: Fri, 18 May 2001 16:27:43 GMT
"Jeffrey Williams" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> Certainly not.
>
> But that is not a good analogy for this situation. This is more along the
> lines of you working for a drug company which won't let you into the
production
> floor to see exactly how they are making aspirin. You may be right: they
may
> be using cyanide. But, then again, you may be wrong. You simply don't
know.
That's not true. People trust boxes labeled "secure" just as they trust
asprin bottles labeled "effective".
I may use your product to (in this case) unlock a key that I use to send
private live or death information to a collegue. I may just like privacy.
Who are you to say "trust us -- it's secure". To me that's the work of
amateurs. For example, when I post cipher ideas to this group I caution
"DONT USE THEM" simply because I want to have a reputation of being a
scientist first, media-whore second.
> Stanley Chow posted a well-written, rational post. You ought to have a
chat
> with him (actually, you ought to have done so before your initial post).
If
> you cannot believe, or trust, him in terms of the contents of his post,
you
> probably ought to look for a new job.
>
> I think, in this case, you are in the wrong. Had you not identified
yourself
> as an employee of Cloakware, then it might reasonably be a freedom of
speech
> issue. As soon as you identified yourself as an employee, you stepped
onto
> thin ice. Most employers have a reasonable expectation that their
employees
> will uphold the reputation of the company.
Who cares where I work*ed*. My concern was genuine and warranted.
Tom
------------------------------
From: jlcooke <[EMAIL PROTECTED]>
Subject: Re: PGP details
Date: 18 May 2001 16:24:02 GMT
Harris Georgiou wrote:
> In the key properties the "Cipher" field reports the algo that WAS default
> when the key was created. Does this mean that this particular key works only
> with this cipher (i.e. CAST), even if my current preference is TripleDES or
> AES? And if so, can I modify this key setting in PGP?
Aska pgp users group. This NG is mostly for theory questions.
> That's true. I was referring to RSA signatures used by PGP. As I understand,
> PGP uses SHA1 digest + encryption with private key for signatures, which is
> the real problem in the first place. I cannot understand if and how the
> private key is protected under this type of attack. Furthermore, what's the
> relation/usage of subkeys with session keys used for normal message
> encryption (totally useless for signatures right)?
This is theory.
I'm sure if you understand that you NEED to use your private key to sign
and not your public key. I mean think about it for a second, if you
signed using your public key...anyone could because it's public right?
And let's not forget the fact that you will only be able to do a
challange-answer test since you can only decrypt a public-key encryption
with the private key and visa versa. That's the key.
Encrypt for intended recipient.
c = E(m, Pub)
m = E(c, Pri)
Sign for everyone to check:
s = E(sha1(m), Pri)
if (E(s, Pub) == sha1(m'))
OK!
else
TAMPERD.
Note: replace sha1(x) with anything else you want. The point here is
Pub-Pri pair are useful because one will undo the operation of the
other, reguardless of which one you start with.
There are precautions you need to take before signing, but generally the
key and data space of public-key algorithms are MUCH larger than
Rijndael-256/256.
JLC
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