NAME    [Toc]    [Back]

       dsa - Digital Signature Algorithm

SYNOPSIS    [Toc]    [Back]

        #include <openssl/dsa.h>
        #include <openssl/engine.h>

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

        int    DSA_size(const 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(const 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,
                       const  unsigned  char *sigbuf, int siglen,
DSA *dsa);

        void DSA_set_default_method(const DSA_METHOD *meth);
        const DSA_METHOD *DSA_get_default_method(void);
        int DSA_set_method(DSA *dsa, const DSA_METHOD *meth);
        DSA *DSA_new_method(ENGINE *engine);
        const 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(const 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(const  DSA  *a,  unsigned   char
**pp);
        int     i2d_DSAPrivateKey(const  DSA  *a,  unsigned  char
**pp);
        int    i2d_DSAparams(const DSA *a,unsigned char **pp);
        int    DSAparams_print(BIO *bp, const DSA *x);
        int    DSAparams_print_fp(FILE *fp, const DSA *x);
        int    DSA_print(BIO *bp, const DSA *x, int off);
        int    DSA_print_fp(FILE *bp, const 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.

       Note that DSA keys may use non-standard DSA_METHOD implementations,
 either directly or by the use of ENGINE modules.
 In some cases (eg. an ENGINE providing support for
       hardware-embedded keys), these BIGNUM values will not be
       used by the implementation or may be used for alternative
       data storage. For this reason, applications should generally
 avoid using DSA structure elements directly and
       instead use API functions to query or modify keys.

CONFORMING TO    [Toc]    [Back]

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

SEE ALSO    [Toc]    [Back]

       bn(3), dh(3), err(3), rand(3), rsa(3), SHA1(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)


OpenBSD 3.6                 2002-09-14                          2