On 2007.05.16 at 12:35:37 -0700, [EMAIL PROTECTED] wrote:

>    I'm running OpenSSL 0.9.8e.  If I set up an ECDSA verify with
>    EC_KEY_new_by_curve_name(NID_X9_62_prime256v1) and call ECDSA_do_verify
>    with dgst (first arg) an array of all zeros and dgst=1 (second arg), the
>    call fails with error 16.

As far as I understand, El Gamal signature scheme is not supposed to
work when digest is all zeros. GOST signature algorithms (which are
simular to DSA/ECDSA) treat this as
special case, and GOST R 34.10 specify that if digest (interpreted as
BIGNUM) is zero, it should be explicitely set to one. I always wondered
why DSA doesn't have such fallback.

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