mainGnuTLS - Support: sr #107940, ECDH key exchange fails if leading...

 
 

sr #107940: ECDH key exchange fails if leading zeros are present

Submitter:  Jack Lloyd <randombit>
Submitted:  Thu 26 Jan 2012 11:29:12 PM UTC
   
 
Category:  Core library Priority:  5 - Normal
Severity:  3 - Normal Status:  None
Privacy:  Public Assigned to:  None
Open/Closed:  Closed Operating System:  None
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Fri 27 Jan 2012 09:15:16 AM UTC, comment #1: 

Hello,
 Please try gnutls 3.0.12 (the latest release) which contains a fix for this issue.

Anonymous
Thu 26 Jan 2012 11:29:12 PM UTC, original submission:  

Unlike TLS's DHE exchange method, which strips leading zeros from the shared secret, ECDH preserves them in the premaster secret (RFC 4492 sec 5.10 "leading zeros found in this octet string MUST NOT be truncated"). It seems that GnuTLS 3.0.11 follows the lead of DH exchange and strips them, so anytime the ECDH exchange results in a Z value which has a leading 0 byte the handshake will fail in the finished step because the two sides will end up with different master secrets.

Jack Lloyd <randombit>

 

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  • -email is unavailable- added by nmav (Updated the item)
  • -email is unavailable- added by randombit (Submitted the item)
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    Date Changed by Updated Field Previous Value => Replaced by
    2012-02-07 nmav Open/ClosedOpen Closed

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