[PYTHON-CRYPTO] Draft hashing PEP

[Andrew Archibald]

On Fri, Mar 23, 2001 at 05:50:31PM -0500, Andrew Kuchling wrote:
> Here's an informational PEP describing the API for hashing that I
> posted to the list last month.  This draft includes the suggested
> revisions of dropping the hexdigest() method and adding clear(),
> adding an optional key argument to the constructor for a hash object.
>
> Comments requested; if there are none, then its status can be changed
> to 'Accepted'.  (No PEP number allocated yet, but I've sent it off to
> Barry to get one.)
>
> --amk

I like it, in general, but I have a few comments:

Currently, sha objects have a digestsize attribute.  This is convenient;
should it be required by the PEP?

How common are variable-size hashes?  (For example, the SHA-160, SHA-256,
SHA-384, SHA-512 family)  Is it worth allowing a module to support multiple
digest sizes?  I would suggest allowing this by having such a module (say
SHA_variable) export a digestsize of 0.  Then new() can accept a digestsize
argument, and each object will have its own digestsize attribute.

Some hashes have additional parameters (HAVAL has a rounds parameter, I
believe); perhaps new should accept arbitrary additional keyword arguments?

What should unkeyed hashes do when presented with a key?  Presumably, raise
an exception.


Thanks,
Andrew