DSAsign(3) OpenSSL DSAsign(3)

NAME
       DSAsign, DSAsignsetup, DSAverify - DSA signatures

SYNOPSIS
        #include 

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

        int    DSAsignsetup(DSA *dsa, BNCTX *ctx, BIGNUM **kinvp,
                       BIGNUM **rp);

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

DESCRIPTION
       DSAsign() computes a digital signature on the lleenn byte message digest
       ddggsstt using the private key ddssaa and places its ASN.1 DER encoding at
       ssiiggrreett. The length of the signature is places in *ssiigglleenn. ssiiggrreett must
       point to DSAsize(ddssaa) bytes of memory.

       DSAsignsetup() may be used to precompute part of the signing
       operation in case signature generation is time-critical. It expects ddssaa
       to contain DSA parameters. It places the precomputed values in newly
       allocated BBIIGGNNUUMMs at *kkiinnvvpp and *rrpp, after freeing the old ones unless
       *kkiinnvvpp and *rrpp are NULL. These values may be passed to DSAsign() in
       ddssaa->>kkiinnvv and ddssaa->>rr.  ccttxx is a pre-allocated BBNNCCTTXX or NULL.

       DSAverify() verifies that the signature ssiiggbbuuff of size ssiigglleenn matches
       a given message digest ddggsstt of size lleenn.  ddssaa is the signer's public
       key.

       The ttyyppee parameter is ignored.

       The PRNG must be seeded before DSAsign() (or DSAsignsetup()) is
       called.

RETURN VALUES
       DSAsign() and DSAsignsetup() return 1 on success, 0 on error.
       DSAverify() returns 1 for a valid signature, 0 for an incorrect
       signature and -1 on error. The error codes can be obtained by
       ERRgeterror(3).

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

SEE ALSO
       dsa(3), ERRgeterror(3), rand(3), DSAdosign(3)

HISTORY       DSAsign() and DSAverify() are available in all versions of SSLeay.
       DSAsignsetup() was added in SSLeay 0.8.



0.9.7l                            2002-09-25                       DSAsign(3)