DSA_set_default_openssl_method(3)DSA_set_default_openssl_method(3)NAME
DSA_set_method, DSA_set_default_openssl_method,
DSA_get_default_openssl_method, DSA_new_method, DSA_OpenSSL - Select
DSA method
SYNOPSIS
#include <openssl/dsa.h> #include <openssl/engine.h>
void DSA_set_default_openssl_method(
DSA_METHOD *meth ); DSA_METHOD *DSA_get_default_openssl_method(
void ); int DSA_set_method(
DSA *dsa, ENGINE *engine ); DSA *DSA_new_method(
ENGINE *engine ); DSA_METHOD *DSA_OpenSSL(
void );
DESCRIPTION
A DSA_METHOD specifies the functions that OpenSSL uses for DSA opera‐
tions. By modifying the method, alternative implementations such as
hardware accelerators can be used.
Initially, the default is the OpenSSL internal implementation. The
DSA_OpenSSL() function returns a pointer to that method.
The DSA_set_default_openssl_method() function makes meth the default
method for all DSA structures created later. This is true only while
the default engine for DSA operations remains as openssl. ENGINEs pro‐
vide an encapsulation for implementations of one or more algorithms at
a time, and all the DSA functions mentioned here operate within the
scope of the default openssl engine.
The DSA_get_default_openssl_method() function returns a pointer to the
current default method for the openssl engine.
The DSA_set_method() selects engine for all operations using the struc‐
ture dsa.
The DSA_new_method() function allocates and initializes a DSA structure
so that engine will be used for the DSA operations. If engine is NULL,
the default engine for DSA operations is used.
THE DSA_METHOD STRUCTURE
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;
RETURN VALUES
The DSA_OpenSSL() and DSA_get_default_openssl_method() functions return
pointers to the respective DSA_METHODs.
The DSA_set_default_openssl_method() function returns no value.
The DSA_set_method() function returns non-zero if the ENGINE associated
with dsa was successfully changed to engine.
The DSA_new_method() function returns NULL and sets an error code that
can be obtained from ERR_get_error() if the allocation fails. Otherwise
it returns a pointer to the newly allocated structure.
HISTORY
The DSA_set_default_method(), DSA_get_default_method(),
DSA_set_method(), DSA_new_method(), and DSA_OpenSSL() functions were
added in OpenSSL 0.9.4.
The DSA_set_default_openssl_method() and
DSA_get_default_openssl_method() functions replaced the
DSA_set_default_method() and DSA_get_default_method() functions respec‐
tively, and the DSA_set_method() and DSA_new_method() functions were
altered to use ENGINEs rather than DSA_METHODs during development of
OpenSSL 0.9.6.
SEE ALSO
Functions: dsa(3), DSA_new(3)DSA_set_default_openssl_method(3)