NAME    [Toc]    [Back]

       DSA_sign, DSA_sign_setup, DSA_verify - DSA signatures

SYNOPSIS    [Toc]    [Back]

        #include <openssl/dsa.h>

        int    DSA_sign(int type, const unsigned char *dgst,  int
len,
                       unsigned   char   *sigret,   unsigned  int
*siglen, DSA *dsa);

        int     DSA_sign_setup(DSA  *dsa,  BN_CTX  *ctx,   BIGNUM
**kinvp,
                       BIGNUM **rp);

        int     DSA_verify(int  type,  const unsigned char *dgst,
int len,
                       unsigned char  *sigbuf,  int  siglen,  DSA
*dsa);

DESCRIPTION    [Toc]    [Back]

       DSA_sign() computes a digital signature on the len byte
       message digest dgst using the private key dsa and places
       its ASN.1 DER encoding at sigret. The length of the signature
 is places in *siglen. sigret must point to
       DSA_size(dsa) bytes of memory.

       DSA_sign_setup() may be used to precompute part of the
       signing operation in case signature generation is
       time-critical. It expects dsa to contain DSA parameters.
       It places the precomputed values in newly allocated
       BIGNUMs at *kinvp and *rp, after freeing the old ones
       unless *kinvp and *rp are NULL. These values may be passed
       to DSA_sign() in dsa->kinv and dsa->r.  ctx is a pre-allocated
 BN_CTX or NULL.

       DSA_verify() verifies that the signature sigbuf of size
       siglen matches a given message digest dgst of size len.
       dsa is the signer's public key.

       The type parameter is ignored.

       The PRNG must be seeded before DSA_sign() (or
       DSA_sign_setup()) is called.

RETURN VALUES    [Toc]    [Back]

       DSA_sign() and DSA_sign_setup() return 1 on success, 0 on
       error.  DSA_verify() returns 1 for a valid signature, 0
       for an incorrect signature and -1 on error. The error
       codes can be obtained by ERR_get_error(3).

CONFORMING TO    [Toc]    [Back]

       US Federal Information Processing Standard FIPS 186 (Digital
 Signature Standard, DSS), ANSI X9.30

SEE ALSO    [Toc]    [Back]

       dsa(3), ERR_get_error(3), rand(3), DSA_do_sign(3)

HISTORY    [Toc]    [Back]

       DSA_sign() and DSA_verify() are available in all versions
       of SSLeay.  DSA_sign_setup() was added in SSLeay 0.8.


OpenBSD 3.6                 2000-04-03                          2