Re: [TLS] TLSv1.2 with DSA client cert and key size >1024 bits

[Nikos Mavrogiannopoulos <[e-mail]>]

On Mon, Feb 14, 2011 at 5:48 PM, Martin Rex <[e-mail]> wrote:
> Dear implementors of TLSv1.2,
> The use of TLSv1.2 with DSA client certs using key lengths > 1024
> as defined by FIPS 186-3 appears slightly underspecified.
> I would like to find out what current implementations of TLSv1.2
> are doing -- and what they are doing when negotiating a protocol
> version less that {0x03,0x03}.
> The base protocol spec does not define what to do with a (L=2048,N=224),
> (L=2048,N=256) or (L=3072,N=256) DSA key from FIPS 186-3 in a client cert
> in TLSv1.1.  rfc4492 Page 20 provides a hint for how to represent
> ECDSA signature values with hash algorithms other than SHA-1 but
> does not describe a means to indicate to the receiver, which
> other hash was actually used.

Currently gnutls uses SHA-1 on versions prior to TLS 1.2. For TLS 1.2
it uses a hash that corresponds to the length of q (i.e. chooses between
SHA-1, SHA-224 and SHA-256).

regards,
Nikos