Re: [keyassure] crypto hash alg deprecation is a myth

[Rob Stradling <[e-mail]>]

On Thursday 03 Mar 2011 05:09:15 Martin Rex wrote:
> Phillip Hallam-Baker wrote:
> > Further, even though we stopped using MD5 in the mid 90s
> 
<snip>
> Firefox happily verifies md5WithRsaEncryption signatures on TLS server
> certs.

Not for much longer.

https://wiki.mozilla.org/CA:MD5and1024 says:
"    * June 30, 2011 – Mozilla will stop accepting MD5 as a hash algorithm for 
intermediate and end-entity certificates. After this date software published 
by Mozilla will return an error when a certificate with an MD5-based signature 
is used.
          o This change is being tracked in 
https://bugzilla.mozilla.org/show_bug.cgi?id=590364"

<snip>
> MSIE 8 on Windows 7 (and prior) will happily talk to TLS servers
> using certs signed not only with md5WithRsaSignature, but also
> md2WithRsaSignature and even (**cough**) md4WithRsaSignature!

http://technet.microsoft.com/en-us/library/cc751157.aspx#EMAA says:
"In the event of an imminent MD5 pre-image attack
Microsoft may update Windows to reject all MD2, MD4 or MD5 end-entity and 
subordinate CA certificates when it has reasons to believe that successful MD5 
pre-image attacks are imminent."

Perhaps somebody should ask them to consider switching off MD2 and MD4 sooner 
than that.

<snip>
> (If it is possible to disable md5WithRsaEncryption signature verification
>  in Firefox 3.5 -- then it is sufficiently well hidden that I don't
>  see it.)

https://bugzilla.mozilla.org/show_bug.cgi?id=590364 suggests setting the 
following environment variable:

NSS_HASH_ALG_SUPPORT=-MD2,-MD5

<snip>

Rob Stradling
Senior Research & Development Scientist
COMODO - Creating Trust Online