Re: RSA Signature Padding

[Rob Stradling <rob.stradling@xxxxxxxxxx>]

On Wednesday 03 June 2009 17:58:45 Santosh Chokhani wrote:
> I do not know if this is the right forum.
>
> Should we encourage vendors to use RSA PSS as we transition to SHA-256
> given the weakness in PKCS 1.5 padding?

Some widely used crypto libraries support SHA-2 but don't (yet) support 
RSA-PSS.  For example:
  - Microsoft Windows CryptoAPI: XP SP 3 and above support SHA-2, but I 
believe that RSA-PSS is only supported in Server 2008 and above.
  - Mozilla NSS: SHA-2 has been supported for a number of years, but RSA-PSS 
has not yet been implemented:
https://bugzilla.mozilla.org/show_bug.cgi?id=158750
  - OpenSSL: SHA-2 has been supported for a number of years, but it looks like 
RSA-PSS is only partly implemented at the moment.  e.g. 
http://www.mail-archive.com/openssl-dev@xxxxxxxxxxx/msg25994.html

Should implementors wait until support for RSA-PSS is sufficiently widespread 
for their needs before migrating from PKCS#1.5/SHA-1 to PKCS#2.1/SHA-2?

Or would an earlier transition from PKCS#1.5/SHA-1 to PKCS#1.5/SHA-2 be wiser 
for cases where RSA-PSS may not be sufficiently supported for some time to 
come?

> Santosh Chokhani
> CygnaCom Solutions
>
> "Questioning conventional wisdom is key to innovation"

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