NAME    [Toc]    [Back]

       dsa - Digital Signature Algorithm

LIBRARY    [Toc]    [Back]

       libcrypto, -lcrypto

SYNOPSIS    [Toc]    [Back]

        #include <openssl/dsa.h>

        DSA *  DSA_new(void);
        void   DSA_free(DSA *dsa);

        int    DSA_size(DSA *dsa);

        DSA *  DSA_generate_parameters(int bits, unsigned char *seed,
                       int seed_len, int *counter_ret, unsigned long *h_ret,
                       void (*callback)(int, int, void *), void *cb_arg);

        DH *   DSA_dup_DH(DSA *r);

        int    DSA_generate_key(DSA *dsa);

        int    DSA_sign(int dummy, 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 dummy, const unsigned char *dgst, int len,
                       unsigned char *sigbuf, int siglen, DSA *dsa);

        void DSA_set_default_method(DSA_METHOD *meth);
        DSA_METHOD *DSA_get_default_method(void);
        DSA_METHOD *DSA_set_method(DSA *dsa, DSA_METHOD *meth);
        DSA *DSA_new_method(DSA_METHOD *meth);
        DSA_METHOD *DSA_OpenSSL(void);

        int DSA_get_ex_new_index(long argl, char *argp, int (*new_func)(),
                    int (*dup_func)(), void (*free_func)());
        int DSA_set_ex_data(DSA *d, int idx, char *arg);
        char *DSA_get_ex_data(DSA *d, int idx);

        DSA_SIG *DSA_SIG_new(void);
        void   DSA_SIG_free(DSA_SIG *a);
        int    i2d_DSA_SIG(DSA_SIG *a, unsigned char **pp);
        DSA_SIG *d2i_DSA_SIG(DSA_SIG **v, unsigned char **pp, long length);

        DSA_SIG *DSA_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
        int    DSA_do_verify(const unsigned char *dgst, int dgst_len,
                    DSA_SIG *sig, DSA *dsa);

        DSA *  d2i_DSAPublicKey(DSA **a, unsigned char **pp, long length);
        DSA *  d2i_DSAPrivateKey(DSA **a, unsigned char **pp, long length);
        DSA *  d2i_DSAparams(DSA **a, unsigned char **pp, long length);
        int    i2d_DSAPublicKey(DSA *a, unsigned char **pp);
        int    i2d_DSAPrivateKey(DSA *a, unsigned char **pp);
        int    i2d_DSAparams(DSA *a,unsigned char **pp);

        int    DSAparams_print(BIO *bp, DSA *x);
        int    DSAparams_print_fp(FILE *fp, DSA *x);
        int    DSA_print(BIO *bp, DSA *x, int off);
        int    DSA_print_fp(FILE *bp, DSA *x, int off);

DESCRIPTION    [Toc]    [Back]

       These functions implement the Digital Signature Algorithm
       (DSA).  The generation of shared DSA parameters is
       described in DSA_generate_parameters(3); DSA_generate_key(3) describes how to generate a signature key. Signature
 generation and verification are described in
       DSA_sign(3).

       The DSA structure consists of several BIGNUM components.

        struct
               {
               BIGNUM *p;              // prime number (public)
               BIGNUM *q;              // 160-bit subprime, q | p-1 (public)
               BIGNUM *g;              // generator of subgroup (public)
               BIGNUM *priv_key;       // private key x
               BIGNUM *pub_key;        // public key y = g^x
               // ...
               }
        DSA;

       In public keys, priv_key is NULL.

CONFORMING TO    [Toc]    [Back]

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

SEE ALSO    [Toc]    [Back]

       openssl_bn(3), openssl_dh(3), openssl_err(3),
       openssl_rand(3), openssl_rsa(3), openssl_sha(3),
       DSA_new(3), DSA_size(3), DSA_generate_parameters(3),
       DSA_dup_DH(3), DSA_generate_key(3), DSA_sign(3),
       DSA_set_method(3), DSA_get_ex_new_index(3), RSA_print(3)



2000-07-22                    0.9.6g                       dsa(3)