DSA_set_method

DSA_set_default_method, DSA_get_default_method, DSA_set_method, DSA_new_method, DSA_OpenSSL ? select RSA method

 #include <openssl/DSA.h>

 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);

A DSA_METHOD specifies the functions that OpenSSL uses for DSA operations. By modifying the method, alternative implementations such as hardware accelerators may be used.

Initially, the default is to use the OpenSSL internal implementation. DSA_OpenSSL() returns a pointer to that method.

DSA_set_default_method() makes meth the default method for all DSA structures created later.

DSA_get_default_method() returns a pointer to the current default method.

DSA_set_method() selects meth for all operations using the structure DSA.

DSA_get_method() returns a pointer to the method currently selected for DSA.

DSA_new_method() allocates and initializes a DSA structure so that method will be used for the DSA operations. If method is NULL, the default method is used.

struct { /* name of the implementation */ const char *name;

     /* sign */
        DSA_SIG *(*dsa_do_sign)(const unsigned char *dgst, int dlen,
                                 DSA *dsa);

     /* pre-compute k^-1 and r */
        int (*dsa_sign_setup)(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
                                 BIGNUM **rp);

     /* verify */
        int (*dsa_do_verify)(const unsigned char *dgst, int dgst_len,
                                 DSA_SIG *sig, DSA *dsa);

     /* compute rr = a1^p1 * a2^p2 mod m (May be NULL for some
                                          implementations) */
        int (*dsa_mod_exp)(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
                                 BIGNUM *a2, BIGNUM *p2, BIGNUM *m,
                                 BN_CTX *ctx, BN_MONT_CTX *in_mont);

     /* compute r = a ^ p mod m (May be NULL for some implementations) */
        int (*bn_mod_exp)(DSA *dsa, BIGNUM *r, BIGNUM *a,
                                 const BIGNUM *p, const BIGNUM *m,
                                 BN_CTX *ctx, BN_MONT_CTX *m_ctx);

     /* called at DSA_new */
        int (*init)(DSA *DSA);

     /* called at DSA_free */
        int (*finish)(DSA *DSA);

        int flags;

        char *app_data; /* ?? */

 } DSA_METHOD;

DSA_OpenSSL(), DSA_get_default_method() and DSA_get_method() return pointers to the respective DSA_METHODs.

DSA_set_default_method() returns no value.

DSA_set_method() returns a pointer to the DSA_METHOD previously associated with dsa.

DSA_new_method() returns NULL and sets an error code that can be obtained by ERR_get_error(3) if the allocation fails. Otherwise it returns a pointer to the newly allocated structure.

dsa(3), DSA_new(3)

DSA_set_default_method(), DSA_get_default_method(), DSA_set_method(), DSA_new_method() and DSA_OpenSSL() were added in OpenSSL 0.9.4.

DSA_new_method, DSA_OpenSSL - select RSA method"