[TLS] DSS with other than SHA-1 algorithms

[Nikos Mavrogiannopoulos <[e-mail]>]

Hello,
 According to FIPS-186-3 the DSA algorithm might
be used with hashes other than SHA-1. Moreover
it mentions:
"A hash function that provides a lower security strength than the (L, N)
pair ordinarily should not be used, since this would reduce the
security strength of the digital signature process to a level no greater
than that provided by the hash function."

So what I understand from that is for the parameters
discussed in the document the SHA variants allowed are:

L = 1024, N = 160: SHA-1 or better
L = 2048, N = 224: SHA-224 or better
L = 2048, N = 256: SHA-256 or better
L = 3072, N = 256: SHA-256 or better

How does this apply to TLS 1.0 and 1.1 messages
"Server Key Exchange" and "Certificate verify"
that sign the handshake data? How is the peer
going to understand which hash is being used?

For TLS 1.2 I suppose that the hash being negotiated
by the signature algorithm extension will be used,
and if it is larger than N, then it will be truncated.

So is my understanding of TLS 1.2 negotiation for DSA
correct? How do you solved the issue in TLS < 1.2?

regards,
Nikos