dsa - Digital Signature Algorithm
SYNOPSIS
#include <openssl/dsa.h>
#include <openssl/engine.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_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);
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_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
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
US Federal Information Processing Standard FIPS 186
(Digital Signature Standard, DSS), ANSI X9.30
SEE ALSO
bn(3), dh(3), err(3), rand(3), rsa(3), 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)
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