[Mailman-Developers] [Bug 985149] [NEW] Add List-Post value to permalink hash input

[Barry Warsaw]

On Apr 18, 2012, at 07:22 PM, Richard Wackerbarth wrote:

>I don't understand the proposal. By "added to this hash", do you mean
>"included in the set of elements that get hashed" or do you mean
>"appended to the hash value"?

I mean "append (or prepend, we have to decide ;) to the hash input.

Specifically.  Let's say you have this message snippet:

    List-Post: foo.example.com
    Message-ID: <bar>

under the current algorithm is:

    >>> from base64 import b32encode
    >>> from hashlib import sha1
    >>> s = sha1('bar')
    >>> b32encode(s.digest())
    'MLG3OAQP7EQOLKTEFQ6UAZUVBXI7AH2N'
    
but after the elaboration suggested in this bug would be:

    >>> s = sha1('bar')
    >>> s.update('foo.example.com')
    >>> b32encode(s.digest())
    'P67IMDMX6CRPP3TXX26OMJEOX2DDK6WN'

>Presumedly, the sole purpose in publishing an algorithm to create the
>hash is to make it possible for two handlers to independently develop
>the same hash given only the message. Otherwise, a "secret" method could
>be used to assign a unique identifier to the message.

Exactly.

>In either case, this suggested change renews my argument that the
>resulting hash should be tagged, visibly, with a "protocol revision
>designator". Omitting that designation transforms the chosen calculation
>method into a "secret".

The way to do that is probably to use a parameter on the header, e.g.

    Permalink-Hash: P67IMDMX6CRPP3TXX26OMJEOX2DDK6WN; version=1