[Twisted-Python] twisted cred: why does avatarId need to be a str?

Stephen Waterbury stephen.c.waterbury at nasa.gov
Wed Sep 8 16:27:37 EDT 2010

A nomenclature distinction that might help this conversation:

*authentication* verifies *identity*
(via, e.g., userid/passwd, public key negotiation, etc.)
and may issue a token (e.g., a cookie, Kerberos TGT, etc.).

*authorization* determines what an authenticated identity
(and its associated roles, if any) have access to in an
application context (realm?).

These are standard terms, and the activities they refer to should
be orthogonal.  Neither the OP nor Glyph use the term
"authorization" in either of their messages, but that concept
is clearly involved and is almost always useful for

Looking at the OAuth 2.0 protocol specification, it seems quite
similar in concept to Kerberos (and other SSO protocols), in
which the user acquires a Ticket-Granting Ticket (TGT) upon
authentication to a Kerberos domain controller, and then the TGT
is used when interacting with applications in the Kerberos
domain.  Each app is registered with the Kerberos domain
controller and can interact with it securely to verify the
validity (also expiration time, etc.) of a TGT that has been
offered to it.  Once that interaction is complete, the app knows
the identity associated with the TGT has been authenticated, and
it can proceed with authorization, which of course depends on
each application's context, and is completely separate from

It might be useful to describe cred's structure in these terms,
since both authentication and authorization are involved.
(Might be useful to me, at least ... :)


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