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127 .TH dsa 3 "2007-10-24" "0.9.8g" "OpenSSL"
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133 dsa \- Digital Signature Algorithm
135 .IX Header "SYNOPSIS"
137 \& #include <openssl/dsa.h>
138 \& #include <openssl/engine.h>
140 \& DSA * DSA_new(void);
141 \& void DSA_free(DSA *dsa);
143 \& int DSA_size(const DSA *dsa);
145 \& DSA * DSA_generate_parameters(int bits, unsigned char *seed,
146 \& int seed_len, int *counter_ret, unsigned long *h_ret,
147 \& void (*callback)(int, int, void *), void *cb_arg);
149 \& DH * DSA_dup_DH(const DSA *r);
151 \& int DSA_generate_key(DSA *dsa);
153 \& int DSA_sign(int dummy, const unsigned char *dgst, int len,
154 \& unsigned char *sigret, unsigned int *siglen, DSA *dsa);
155 \& int DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp,
157 \& int DSA_verify(int dummy, const unsigned char *dgst, int len,
158 \& const unsigned char *sigbuf, int siglen, DSA *dsa);
160 \& void DSA_set_default_method(const DSA_METHOD *meth);
161 \& const DSA_METHOD *DSA_get_default_method(void);
162 \& int DSA_set_method(DSA *dsa, const DSA_METHOD *meth);
163 \& DSA *DSA_new_method(ENGINE *engine);
164 \& const DSA_METHOD *DSA_OpenSSL(void);
166 \& int DSA_get_ex_new_index(long argl, char *argp, int (*new_func)(),
167 \& int (*dup_func)(), void (*free_func)());
168 \& int DSA_set_ex_data(DSA *d, int idx, char *arg);
169 \& char *DSA_get_ex_data(DSA *d, int idx);
171 \& DSA_SIG *DSA_SIG_new(void);
172 \& void DSA_SIG_free(DSA_SIG *a);
173 \& int i2d_DSA_SIG(const DSA_SIG *a, unsigned char **pp);
174 \& DSA_SIG *d2i_DSA_SIG(DSA_SIG **v, unsigned char **pp, long length);
176 \& DSA_SIG *DSA_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
177 \& int DSA_do_verify(const unsigned char *dgst, int dgst_len,
178 \& DSA_SIG *sig, DSA *dsa);
180 \& DSA * d2i_DSAPublicKey(DSA **a, unsigned char **pp, long length);
181 \& DSA * d2i_DSAPrivateKey(DSA **a, unsigned char **pp, long length);
182 \& DSA * d2i_DSAparams(DSA **a, unsigned char **pp, long length);
183 \& int i2d_DSAPublicKey(const DSA *a, unsigned char **pp);
184 \& int i2d_DSAPrivateKey(const DSA *a, unsigned char **pp);
185 \& int i2d_DSAparams(const DSA *a,unsigned char **pp);
187 \& int DSAparams_print(BIO *bp, const DSA *x);
188 \& int DSAparams_print_fp(FILE *fp, const DSA *x);
189 \& int DSA_print(BIO *bp, const DSA *x, int off);
190 \& int DSA_print_fp(FILE *bp, const DSA *x, int off);
193 .IX Header "DESCRIPTION"
194 These functions implement the Digital Signature Algorithm (\s-1DSA\s0). The
195 generation of shared \s-1DSA\s0 parameters is described in
196 \&\fIDSA_generate_parameters\fR\|(3);
197 \&\fIDSA_generate_key\fR\|(3) describes how to
198 generate a signature key. Signature generation and verification are
199 described in \fIDSA_sign\fR\|(3).
201 The \fB\s-1DSA\s0\fR structure consists of several \s-1BIGNUM\s0 components.
206 \& BIGNUM *p; // prime number (public)
207 \& BIGNUM *q; // 160\-bit subprime, q | p\-1 (public)
208 \& BIGNUM *g; // generator of subgroup (public)
209 \& BIGNUM *priv_key; // private key x
210 \& BIGNUM *pub_key; // public key y = g^x
216 In public keys, \fBpriv_key\fR is \s-1NULL\s0.
218 Note that \s-1DSA\s0 keys may use non-standard \fB\s-1DSA_METHOD\s0\fR implementations,
219 either directly or by the use of \fB\s-1ENGINE\s0\fR modules. In some cases (eg. an
220 \&\s-1ENGINE\s0 providing support for hardware-embedded keys), these \s-1BIGNUM\s0 values
221 will not be used by the implementation or may be used for alternative data
222 storage. For this reason, applications should generally avoid using \s-1DSA\s0
223 structure elements directly and instead use \s-1API\s0 functions to query or
226 .IX Header "CONFORMING TO"
227 \&\s-1US\s0 Federal Information Processing Standard \s-1FIPS\s0 186 (Digital Signature
228 Standard, \s-1DSS\s0), \s-1ANSI\s0 X9.30
230 .IX Header "SEE ALSO"
231 \&\fIbn\fR\|(3), \fIdh\fR\|(3), \fIerr\fR\|(3), \fIrand\fR\|(3),
232 \&\fIrsa\fR\|(3), \fIsha\fR\|(3), \fIengine\fR\|(3),
233 \&\fIDSA_new\fR\|(3),
234 \&\fIDSA_size\fR\|(3),
235 \&\fIDSA_generate_parameters\fR\|(3),
236 \&\fIDSA_dup_DH\fR\|(3),
237 \&\fIDSA_generate_key\fR\|(3),
238 \&\fIDSA_sign\fR\|(3), \fIDSA_set_method\fR\|(3),
239 \&\fIDSA_get_ex_new_index\fR\|(3),
240 \&\fIRSA_print\fR\|(3)