Re: MD5 value security consideration

Graham Klyne wrote

> 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.

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 protected]