dsa-sha1-verify.c, dsa-sha256-sign.c, and dsa-sha256-verify.c.

* dsa.h: Updated and added dsa declarations.

* dsa-sha256-verify.c (dsa_sha256_verify_digest): New file, new
function.
(dsa_sha256_verify): New function.
* dsa-sha256-sign.c (dsa_sha256_sign_digest): New file, new
function.
(dsa_sha256_sign): New function.

* dsa-sha1-verify.c (dsa_sha1_verify_digest): New file. Moved and
renamed function, from dsa_verify_digest, rewrote to use
_dsa_verify.
(dsa_sha1_verify): Analogous change, renamed from dsa_verify.
* dsa-sha1-sign.c (dsa_sha1_sign_digest): New file. Moved and
renamed function, from dsa_sign_digest, rewrote to use _dsa_sign,
and added return value.
(dsa_sha1_sign): Analogous change, renamed from dsa_sign.

* dsa-verify.c (_dsa_verify): New general verification function,
for any hash.
* dsa-sign.c (_dsa_sign): New general signing function, for any
hash. Returns success code, like the rsa signture functions.

Rev: nettle/ChangeLog:1.71
Rev: nettle/Makefile.in:1.22
Rev: nettle/dsa-sha1-sign.c:1.1
Rev: nettle/dsa-sha1-verify.c:1.1
Rev: nettle/dsa-sha256-sign.c:1.1
Rev: nettle/dsa-sha256-verify.c:1.1
Rev: nettle/dsa-sign.c:1.3
Rev: nettle/dsa-verify.c:1.3
Rev: nettle/dsa.h:1.4