Subject: Re: [hiprg] Russ Housley's Discuss on draft-irtf-hiprg-dht-04: (with DISCUSS)

From: "Ahrenholz, Jeffrey M" <[email-masked]>
Date: Wed, 2 Nov 2011 09:15:32 -0700

> ----------------------------------------------------------------------
> DISCUSS:
> ----------------------------------------------------------------------
> 
> 
>   The Gen-ART Review by Kathleen Moriarty on 20-Oct-2011 raised a
>   concern about the use of SHA-1.  The authors said a change would be
>   made, but it has not been posted yet.
> 

Below is new proposed text for the Security Considerations section of this draft.
Does this sufficiently address the comments with regards to the use of SHA-1?

thanks,
-Jeff

"
   The SHA-1 message digest algorithm is used in two ways in this
   document, and the security of using this algorithm should be
   considered within the context of [RFC6194].  The first use is with
   the OpenDHT put and remove operations, described in Section 2, and
   the second is to reduce the size of the name string for the HIT
   lookup service in Section 4.1.

   The first use is intended to protect the secret values used to store
   records in the DHT as described by the OpenDHT interface.  An
   attacker would be able to remove a record, after capturing the
   plaintext put, if a secret value could be found that produces the
   same secret hash.  The purpose of this document is to maintain
   interoperable compatibility with that interface, which prescribes the
   use of SHA-1.  Future revisions of that interface should consider
   hash algorithm agility.  The OpenDHT FAQ states that future support
   for other hash algorithms is planned.

   The second use of the SHA-1 algorithm is to reduce the arbitrarily-
   sized name strings to fit the fixed OpenDHT key size.  No security
   properties of the SHA-1 algorithm are used in this context.
"