Re: [pkix] Initial inquiry: Signed vCards

Y = MAC(message, KeySymmetric)

Sig = Sign(message, KeyPrivate)

Both generate an output that can be verified.  In the case of a signature
algorithm, the recipient uses a public key to verify the signature.  In the
case of a MAC algorithm, the recipient uses the same symmetric key for
verification as was used for creation.

Jim


> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of DataPacRat
> Sent: Tuesday, October 22, 2013 1:20 PM
> To: Jim Schaad
> Cc: [email protected]
> Subject: Re: [smime] [pkix] Initial inquiry: Signed vCards
> 
> On Tue, Oct 22, 2013 at 3:57 PM, Jim Schaad <[email protected]>
> wrote:
> > I may be missing something, but I do not see how using a MAC function
> > is going to provide any degree of security in this case.
> >
> > The basic presumption of using a MAC function is that the secret is
> > known only to two people.  The generator and the consumer.  If it is
> > known to multiple people, especially if it is advertised in a URL,
> > then a new MAC value can be created by anybody that can get the secret
> > value and a new vcard substituted.
> 
> From Sean Turner's suggestion, I assumed that 'output of a HMAC' was
> effectively a synonym for 'the authentication hash generated by the
relevant
> key's algorithm'. If that's not the case, such as only applying to email
rather
> than encryption in general, then that change may need to be changed.
> 
> 
> Thank you for your time,
> --
> DataPacRat
> "Then again, I could be wrong."
> _______________________________________________
> smime mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/smime

_______________________________________________
smime mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/smime