In FIPS 186-1 and 186-2 L could be any number between 512 and 1024 (inclusive) that was a multiple of 64. N was fixed at 160.
FIPS 186-3 changed it so that L and N could be any combination of the following:
- L = 1024, N = 160
- L = 2048, N = 224
- L = 2048, N = 256
- L = 3072, N = 256
RFC 4253 (SSH Transport Layer Protocol) says the following:
The resulting signature is encoded as follows: string "ssh-dss" string dss_signature_blob The value for 'dss_signature_blob' is encoded as a string containing r, followed by s (which are 160-bit integers, without lengths or padding, unsigned, and in network byte order).
So I take it this means SSH does not support 2048-bit DSA? Are there no RFCs that add support for them? No vendor extensions?