In the process, we add a "randfunc" parameter to
- Crypto.Cipher.PKCS1_OAEP.new()
- Crypto.Cipher.PKCS1_v1_5.new()
- Crypto.Signature.PKCS1_PSS.new()
to set the PRNG used by each algorithm.
Previously, the PRNG was taken from the RSA key itself.
This patch does a few things to simplify the public key classes
(RSA, DSA and ElGamal):
* It removes the Crypto.PublicKey.pubkey module. The 3 classes
do not have an ancestor anymore.
* Methods sign(), verify(), encrypt(), and decrypt() are removed.
* Methods blind() and unblind() are removed.
* Methods can_sign() and can_encrypt() are removed.
* The 3 classes cannot be pickled anymore.
