RE: Problems with Example 5.1.

Steve,

I agree with your first comment that "DH-DSS" should be "DSA".  This is true
for all occurrences of "DH-DSS" in the document.

We will use the S/MIME Freeware Library to re-test example 5.1 as extracted
from the Examples-06 document.

===========================================
John Pawling, [email protected]
Getronics Government Solutions, LLC
===========================================


-----Original Message-----
From: Dr S N Henson [mailto:[email protected]]
Sent: Friday, March 23, 2001 8:58 AM
To: [email protected]
Cc: Pawling, John
Subject: Problems with Example 5.1.


It has been reported to me that OpenSSL has problems verifying the
signature on example 5.1.

I have now analysed the example and found a few issues.

Firstly the description:

> A SignedData with no attribute certificates, signed by Alice using
> DH-DSS, just her certificate (not Carl's root cert), no CRL. The
> message is ExContent, and is included in the eContent. There are no
> signed or unsigned attributes.
> 

DH-DSS??

The final OCTET STRING which encapsulates the signature includes a
trailing zero.

Finally I cannot get OpenSSL to verify the signature on that example.
OpenSSL does however verify the signature on the certificate.

I didn't immediately report this because I could not be certain there
wasn't a bug in OpenSSLs DSA implementation that this example triggered.

I have since manually implemented the DSA verification algorithm for
this example using the Unix 'dc' calculator and input the relevant
values.

The result from dc agrees with OpenSSL: that is the value for 'v' is
identical (see FIPS186 section 6) not just the fact that it cannot
verify the signature.

While I cannot rule out the possibility that I've done something silly
the evidence suggests there is a problem with that signature.

Steve.
-- 
Dr Stephen N. Henson.   http://www.drh-consultancy.demon.co.uk/
Personal Email: [email protected] 
Senior crypto engineer, Celo Communications: http://www.celocom.com/
Core developer of the   OpenSSL project: http://www.openssl.org/
Business Email: [email protected] PGP key: via homepage.