Subject: MD5 value security consideration

From: Graham Klyne <[email-masked]>
Date: Thu, 04 Mar 1999 10:08:16 +0000

I noticed this in a recent I-D, and thought it might appropriate to mention
something similar in the security considerations of our drafts that suggest
use of MD5.

   Implementations should take care not to assume that the value of the
   Content-MD5: header will always be 24 bytes or less - to avoid buffer
   overrun problems.  It would also be unwise to assume that the
   characters in an arbitrary Content-MD5: header will be chosen from
   the base64 character set mandated by RFC 1864.

#g

------------
Graham Klyne
([email-masked])

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From: Bill Newman <[email-masked]>
Date: Thu, 4 Mar 1999 10:03:19 -0800 (PST)

Graham Klyne wrote

>    the base64 character set mandated by RFC 1864.

Perhaps I'm missing something, but this doesn't look like a special
security consideration.  It seems to me that in both your I-D and
mine, the possibility of buffer overflow or unexpected characters for
hash values has the same security consequences as any other buffer
overflow or unexpected character: a buggy parser could blow up as
easily on a 2000-character property name or a 2000-level-deep feature
set expression or a file containing ASCII 0 as on a bogus hash
value. a properly constructed parser will either turn something into a
valid MD5 value or detect an error condition.

  Bill Newman
  [email-masked]