Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-rc4-01.txt

[[e-mail] (Martin Rex)]

Hanno Böck wrote:
> 
> I really don't want to hold anything here and would welcome if this
> gets finally out, however there's one thing that bothers me:
> There is currently no such RFC for RC2 or DES. Both are - considering
> current RFCs - perfectly valid ciphers according to RFC 2246.
> 
> It doesn't really make sense to forbid RC4 (likely weak, but no
> public practical attacks yet) while still allowing RC2(40 bit)/DES
> (practically broken).

not quite.

TLS cipher suites with three symmetric encryption algorithms
that are described in the TLSv1.1 spec (rfc4346) no longer appear
in TLSv1.2 (rfc5246):   RC2, (single-)DES, and IDEA

For two of these three TLS cipher(suites), a seperate RFC was issued:

  http://tools.ietf.org/html/rfc5469

RC2 may have been left out since it existed only as RC2-40 in SSLv3&TLS.


I prefer the rfc5469 approach by a significant margin over the
science-defying dogmatic, radical extremist approach of the rc4 I-D.
Attacking a single-DES TLS session is *VERY* practical.

Attacking a dozen RC4-encrypted TLS-sessions is infeasible based on
all that we currently know.


-Martin