[FIX] Crypto changes

> from preamble:
>
> "Change Set:            Crypto changes
> Date:                   23 November 2006
> Author:                 Timothy J. Miller
>
> Changed e to 65537."!
>
>
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>
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> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of
> [hidden email]
> Sent: None
> To: [hidden email]
> Subject: [Cryptography Team] [FIX] Crypto changes
>
> from preamble:
>
> "Change Set: Crypto changes
> Date: 23 November 2006
> Author: Timothy J. Miller
>
> Changed e to 65537."!

> -----Original Message-----
> From:
> Cerebus
> Sent: Friday, November 24, 2006 3:10 PM
> On 11/24/06, Ron Teitelbaum <[hidden email]> wrote:
>
> > We still need to review our validation of e=3 signatures.  Did you have
> a
> > look at that?  Is there any way that reading ASN.1 would stop and leave
> more
> > data past the hash without throwing an error?
>
> I think I'm missing something here.  PKCS#1 signatures require
> digesting, encoding, encrypting, and then conversion to bit-string.
> The encoding step takes the hash and wraps it in the following ASN.1:
>
> DigestInfo ::= SEQUENCE {
>   digestAlgorithm DigestAlgorithmIdentifier,
>   digest Digest }
>
> DigestAlgorithmIdentifier ::= AlgorithmIdentifier
>
> Digest ::= OCTET STRING
>
> I'm looking at RSAKey>>v15SignMessageHash: and
> RSAKey>>v15VerifySignature:ofMessageHash and the encoding step is
> being skipped.
>
> Or am I misusing RSAKey?  Or do I have an old version?  (I'm still
> figuring out this whole Squeak packaging mess.)
>
> In re: the question, it looks to me like validation is not currently
> vulnerable to the attack because
> RSAKey>>v15VerifySignature:ofMessageHash: isn't doing any ASN.1
> decoding to attack!  :)
>
> -- Tim
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> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of
> Cerebus
> Sent: Friday, November 24, 2006 5:40 PM
> To: [hidden email]; Cryptography Team Development List
> Subject: Re: RE: RE: [Cryptography Team] [FIX] Crypto changes
>
> On 11/24/06, Ron Teitelbaum <[hidden email]> wrote:
> > No I don't think you are missing anything, I still haven't had time to
> check
> > the code.  The real question is after determining the hash if there is
> data
> > left over it should error out.  Thanks for looking at it I'll take a
> look
> > too.
>
> If I'm not missing anything, then doesn't this mean that the
> implementation is incorrect?
>
> -- Tim
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