[PYTHON-CRYPTO] A pythonic way of calling crypto algorithms

[Treutwein Guido]

Hi all,

I'm not sure how settled the design is in respect to calling the algorithm,
once it is found via the mechanisms discussed here, but we found the
following approach quite useful:
        # alg() is assumed to be a cryptographic algorithm

        cipher = alg(plain="something", key=aKey)
#encrypt or signature generation or MAC computation
        plain  = alg(cipher="$#qq!", key=aKey)
#decrypt
                alg(plain="something", cipher="$#qq!", key=aKey)        #MAC
or signature verification
In the last case its a matter of taste, whether an exception results in the
mismatch case, or something true is returned in the match case (e.g.
timestamp) or both.

The advantages are
- everything can be handled within the algorithm itself (so a hashing
function would reject the decrpytion by raising an exception)
- all types of algorithms can be called uniformly
- no magic constants are needed for encryption/decryption

Guido Treutwein
guido.treutwein at nbg.siemens.de