Thank you,
after modification crypto/pkcs7/pk7_smime.c (calling EVP_sha256 instead
EVP_sha1 on PKCS7_sign()) signature really containts digest by sha256 and
verification of this signature is successful. Great.
It is the simplest way how to still use openssl by command line only.
------------------
But what about the future?
Digest algorithm SHA-1 will be marked as "unusable" on EU from 1.1.2010
(because security experts expects breaking SHA-1 soon).
Will non-modified openssl on command line still create only SHA-1
signatures (PKCS#7)? Or will non-modified openssl on command line offer choosing
digest algorithm e.g. by implementation "-md" option what is mentioned on
http://www.openssl.org/docs/apps/smime.html#?
Thanks, V. Benes
-----Original Message-----
From: owner-openssl-us...@openssl.org [mailto:owner-openssl-us...@openssl.org]
On Behalf Of Paul Allen
Sent: Tuesday, March 31, 2009 7:38 PM
To: openssl-users@openssl.org
Subject: Re: "openssl smime ... [-md digest] ..." seems to be unknown option
ontle last version openssl
On Tue, 2009-03-31 at 08:50 -0700, Beneš Vladimír wrote:
> Hi,
>
> there is mentioned command option "-md" on official documentation -
http://www.openssl.org/docs/apps/smime.html#
> """
> SYNOPSIS
> openssl smime ... [-md digest] ...
> ...
> COMMAND OPTIONS
> ...
> -md digest
> digest algorithm to use when signing or resigning. If not present then the
default digest algorithm for the signing key will be used (usually SHA1).
> ...
> """
>
> But if I try to use it (in the latest version - OpenSSL 0.9.8k 25 Mar
2009), it seems that this is quite unknown option (it only puts into stderr
available options - without "-md" option).
>
> So how option "-md" could by used in "openssl smime"?
> Or - how could be created and verificated PKCS#7 signatures with the
sha512 (or sha256) message digest algorithm?
As you have noticed, apps/smime.c doesn't implement the -md command-line
switch. The bit of code that actually specifies the message digest to
use for signing is in PKCS7_sign() in crypto/pkcs7/pk7_smime.c. It is
hard-coded to use SHA1. I changed EVP_sha1 to EVP_sha256 in the call
to PKCS7_add_signature(), and it seems to work fine. (By that, I mean
SHA256 is actually getting used and signatures verify OK.) There's
almost certainly a better way to go about this, but I didn't need a
general solution to the command-line problem.
Paul
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smime.p7s
Description: S/MIME cryptographic signature
