William H. Geiger III, <whgiii(_at_)invweb(_dot_)net>, writes:
In common disscussion of public key encryption when one talks of
"Encryption" of a message they are most definatly not speaking of
encrypting with ones secret key.
I guess one could encrypt the entire message with ones secret key and
bypass the use of the hash but it is not a practice I would recomend and
it clouds the distinction between standard "encryption" & "signatures"
from a legal standpoint.
Furthermore, it is not meaningful in general to describe a signature as
encryption with the private key. RSA signatures happen to work that way,
but discrete log signatures do not. Rather, there is a verification
formula which takes the message hash, the public key, and the signature
values, and is used to check that the signature is correct. It's very
different from either encryption or decryption.
Hal Finney
hal(_at_)pgp(_dot_)com