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141 .TH dsa 3 "0.9.7a" "2003-02-19" "OpenSSL"
144 dsa \- Digital Signature Algorithm
146 .IX Header "SYNOPSIS"
148 \& #include <openssl/dsa.h>
149 \& #include <openssl/engine.h>
152 \& DSA * DSA_new(void);
153 \& void DSA_free(DSA *dsa);
156 \& int DSA_size(const DSA *dsa);
159 \& DSA * DSA_generate_parameters(int bits, unsigned char *seed,
160 \& int seed_len, int *counter_ret, unsigned long *h_ret,
161 \& void (*callback)(int, int, void *), void *cb_arg);
164 \& DH * DSA_dup_DH(const DSA *r);
167 \& int DSA_generate_key(DSA *dsa);
170 \& int DSA_sign(int dummy, const unsigned char *dgst, int len,
171 \& unsigned char *sigret, unsigned int *siglen, DSA *dsa);
172 \& int DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp,
174 \& int DSA_verify(int dummy, const unsigned char *dgst, int len,
175 \& const unsigned char *sigbuf, int siglen, DSA *dsa);
178 \& void DSA_set_default_method(const DSA_METHOD *meth);
179 \& const DSA_METHOD *DSA_get_default_method(void);
180 \& int DSA_set_method(DSA *dsa, const DSA_METHOD *meth);
181 \& DSA *DSA_new_method(ENGINE *engine);
182 \& const DSA_METHOD *DSA_OpenSSL(void);
185 \& int DSA_get_ex_new_index(long argl, char *argp, int (*new_func)(),
186 \& int (*dup_func)(), void (*free_func)());
187 \& int DSA_set_ex_data(DSA *d, int idx, char *arg);
188 \& char *DSA_get_ex_data(DSA *d, int idx);
191 \& DSA_SIG *DSA_SIG_new(void);
192 \& void DSA_SIG_free(DSA_SIG *a);
193 \& int i2d_DSA_SIG(const DSA_SIG *a, unsigned char **pp);
194 \& DSA_SIG *d2i_DSA_SIG(DSA_SIG **v, unsigned char **pp, long length);
197 \& DSA_SIG *DSA_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
198 \& int DSA_do_verify(const unsigned char *dgst, int dgst_len,
199 \& DSA_SIG *sig, DSA *dsa);
202 \& DSA * d2i_DSAPublicKey(DSA **a, unsigned char **pp, long length);
203 \& DSA * d2i_DSAPrivateKey(DSA **a, unsigned char **pp, long length);
204 \& DSA * d2i_DSAparams(DSA **a, unsigned char **pp, long length);
205 \& int i2d_DSAPublicKey(const DSA *a, unsigned char **pp);
206 \& int i2d_DSAPrivateKey(const DSA *a, unsigned char **pp);
207 \& int i2d_DSAparams(const DSA *a,unsigned char **pp);
210 \& int DSAparams_print(BIO *bp, const DSA *x);
211 \& int DSAparams_print_fp(FILE *fp, const DSA *x);
212 \& int DSA_print(BIO *bp, const DSA *x, int off);
213 \& int DSA_print_fp(FILE *bp, const DSA *x, int off);
216 .IX Header "DESCRIPTION"
217 These functions implement the Digital Signature Algorithm (\s-1DSA\s0). The
218 generation of shared \s-1DSA\s0 parameters is described in
219 DSA_generate_parameters(3);
220 DSA_generate_key(3) describes how to
221 generate a signature key. Signature generation and verification are
222 described in DSA_sign(3).
224 The \fB\s-1DSA\s0\fR structure consists of several \s-1BIGNUM\s0 components.
229 \& BIGNUM *p; // prime number (public)
230 \& BIGNUM *q; // 160-bit subprime, q | p-1 (public)
231 \& BIGNUM *g; // generator of subgroup (public)
232 \& BIGNUM *priv_key; // private key x
233 \& BIGNUM *pub_key; // public key y = g^x
238 In public keys, \fBpriv_key\fR is \s-1NULL\s0.
240 Note that \s-1DSA\s0 keys may use non-standard \fB\s-1DSA_METHOD\s0\fR implementations,
241 either directly or by the use of \fB\s-1ENGINE\s0\fR modules. In some cases (eg. an
242 \&\s-1ENGINE\s0 providing support for hardware-embedded keys), these \s-1BIGNUM\s0 values
243 will not be used by the implementation or may be used for alternative data
244 storage. For this reason, applications should generally avoid using \s-1DSA\s0
245 structure elements directly and instead use \s-1API\s0 functions to query or
248 .IX Header "CONFORMING TO"
249 \&\s-1US\s0 Federal Information Processing Standard \s-1FIPS\s0 186 (Digital Signature
250 Standard, \s-1DSS\s0), \s-1ANSI\s0 X9.30
252 .IX Header "SEE ALSO"
253 bn(3), dh(3), err(3), rand(3),
254 rsa(3), sha(3), engine(3),
257 DSA_generate_parameters(3),
260 DSA_sign(3), DSA_set_method(3),
261 DSA_get_ex_new_index(3),