Subject: Re: Update request for RFC3279 and 4055

From: "David A. Cooper" <[email-masked]>
Date: Wed, 28 Mar 2007 12:39:19 -0400

Scott Shorter wrote:  
> However, Subject Key Identifiers and Authority Key Identifiers are 
> defined in sections 4.2.1.2 and 4.2.1.1 of RFC3280 as using SHA-1 
> only.  A quick search of the forum archives reveals that this has been 
> discussed, but I must confess that I don't read the mailing list 
> religiously enough to know if there is a resolution and if so what it is.
In RFC 3280 the two methods described for generating key identifiers 
from keys both use SHA-1 and the text RECOMMENDS generating key 
identifiers using one of the methods described in the document.  In 
3280bis, the the two methods described for generating key identifiers 
from keys are the same as in RFC 3280, but the recommendation has been 
changed to read:

      Two common methods for generating key identifiers from
      the public key are described in section 4.2.1.2.  Where a
      key identifier has not been previously established, this
      specification RECOMMENDS use of one of these methods
      for generating keyIdentifiers _or use of a similar method that
      uses a different hash algorithm_.

So, 3280bis now specifically notes that hash algorithms other than SHA-1 
may be used to generate key identifiers.

As with the fingerprint/thumbprint displayed by certificate viewers, the 
use of a weak hash algorithm does not create any problems, security or 
otherwise.  Furthermore, since the certificate does not specify the 
method by which the key identifiers were generated, the use of SHA-1 is 
unlikely to even lead to perception problems since very few relying 
parties would be able to determine that SHA-1 was used to generate the 
key identifiers, and those who did determine this would most likely be 
knowledgeable enough to understand that it is OK to use SHA-1 to 
generate key identifiers even if it is too weak to use in other places.

Dave

---

From: Paul Hoffman <[email-masked]>
Date: Wed, 28 Mar 2007 10:43:07 -0700

At 3:34 PM +0200 3/28/07, Rajesh Lachman wrote:
>smime 1.p7m

Please send plain-text messages to the WG mailing list. This message 
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--VPN Consortium