Encrypting krb_rced messages in GSSAPI tokens

Nicolas.Williams@ubsw.com Nicolas.Williams at ubsw.com
Mon Apr 29 17:16:00 EDT 2002

Suggestion: change mk_req_extended() (or make a new API) that takes a callback function pointer and make it so the callback function gets called with the ticket key and subkey blocks; the callback function should return data for use in the checksum field.


> -----Original Message-----
> From: Sam Hartman [mailto:hartmans at mit.edu]
> Sent: Monday, April 29, 2002 4:55 PM
> To: krbdev at mit.edu
> Subject: Encrypting krb_rced messages in GSSAPI tokens
> Traditionally, MIT has not encrypted the krb_cred message in the
> GSSAPI token.  This is a problem because it violates RFC 1510 and is
> going to violate successor documents.
> We've indicated here and on the IETF working group list that we plan
> to continue not encrypting the krb_cred message for all our current
> crypto systems (DES and 3DES)  but to encrypt for future crypto
> systems (AES, RC4, etc).
> I'm not quite sure how to implement this.  Currently, the code in
> lib/gssapi/krb5/init_sec_context.c constructs the krb_cred before
> calling krb5_mk_req_extended.
> This is problematic because:
> * The mk_req sets up the key and subkey in the auth_context
> * the  mk_cred needs these keys to encrypt
> * The mk_req takes a structure containing the completed krb_cred as
>   input.
> I'm not really sure how to handle this.  The subkey is particularly
> annoying because the subkey is generated  randomly during the mk_req
> call.
> Thoughts would be welcome on how to restructure interfaces or
> otherwise handle this issue.
> _______________________________________________
> krbdev mailing list             krbdev at mit.edu
> http://mailman.mit.edu/mailman/listinfo/krbdev

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