Upgrade to OpenSSL 0.9.8h.
[dragonfly.git] / secure / lib / libcrypto / man / dh.3
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129.\" ========================================================================
130.\"
131.IX Title "dh 3"
aac4ff6f 132.TH dh 3 "2008-09-06" "0.9.8h" "OpenSSL"
984263bc 133.SH "NAME"
8b0cefbb 134dh \- Diffie\-Hellman key agreement
984263bc 135.SH "SYNOPSIS"
8b0cefbb 136.IX Header "SYNOPSIS"
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137.Vb 2
138\& #include <openssl/dh.h>
139\& #include <openssl/engine.h>
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140.Ve
141.PP
142.Vb 2
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143\& DH * DH_new(void);
144\& void DH_free(DH *dh);
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145.Ve
146.PP
147.Vb 1
984263bc 148\& int DH_size(const DH *dh);
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149.Ve
150.PP
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152\& DH * DH_generate_parameters(int prime_len, int generator,
153\& void (*callback)(int, int, void *), void *cb_arg);
154\& int DH_check(const DH *dh, int *codes);
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155.Ve
156.PP
157.Vb 2
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158\& int DH_generate_key(DH *dh);
159\& int DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh);
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160.Ve
161.PP
162.Vb 5
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163\& void DH_set_default_method(const DH_METHOD *meth);
164\& const DH_METHOD *DH_get_default_method(void);
165\& int DH_set_method(DH *dh, const DH_METHOD *meth);
166\& DH *DH_new_method(ENGINE *engine);
167\& const DH_METHOD *DH_OpenSSL(void);
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168.Ve
169.PP
170.Vb 4
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171\& int DH_get_ex_new_index(long argl, char *argp, int (*new_func)(),
172\& int (*dup_func)(), void (*free_func)());
173\& int DH_set_ex_data(DH *d, int idx, char *arg);
174\& char *DH_get_ex_data(DH *d, int idx);
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175.Ve
176.PP
177.Vb 2
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178\& DH * d2i_DHparams(DH **a, unsigned char **pp, long length);
179\& int i2d_DHparams(const DH *a, unsigned char **pp);
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180.Ve
181.PP
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183\& int DHparams_print_fp(FILE *fp, const DH *x);
184\& int DHparams_print(BIO *bp, const DH *x);
185.Ve
186.SH "DESCRIPTION"
8b0cefbb 187.IX Header "DESCRIPTION"
984263bc 188These functions implement the Diffie-Hellman key agreement protocol.
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189The generation of shared \s-1DH\s0 parameters is described in
190\&\fIDH_generate_parameters\fR\|(3); \fIDH_generate_key\fR\|(3) describes how
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191to perform a key agreement.
192.PP
8b0cefbb 193The \fB\s-1DH\s0\fR structure consists of several \s-1BIGNUM\s0 components.
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194.PP
195.Vb 9
196\& struct
197\& {
198\& BIGNUM *p; // prime number (shared)
199\& BIGNUM *g; // generator of Z_p (shared)
200\& BIGNUM *priv_key; // private DH value x
201\& BIGNUM *pub_key; // public DH value g^x
202\& // ...
203\& };
204\& DH
205.Ve
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206.PP
207Note that \s-1DH\s0 keys may use non-standard \fB\s-1DH_METHOD\s0\fR implementations,
208either directly or by the use of \fB\s-1ENGINE\s0\fR modules. In some cases (eg. an
209\&\s-1ENGINE\s0 providing support for hardware-embedded keys), these \s-1BIGNUM\s0 values
984263bc 210will not be used by the implementation or may be used for alternative data
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211storage. For this reason, applications should generally avoid using \s-1DH\s0
212structure elements directly and instead use \s-1API\s0 functions to query or
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213modify keys.
214.SH "SEE ALSO"
74dab6c2 215.IX Header "SEE ALSO"
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216\&\fIdhparam\fR\|(1), \fIbn\fR\|(3), \fIdsa\fR\|(3), \fIerr\fR\|(3),
217\&\fIrand\fR\|(3), \fIrsa\fR\|(3), \fIengine\fR\|(3),
218\&\fIDH_set_method\fR\|(3), \fIDH_new\fR\|(3),
219\&\fIDH_get_ex_new_index\fR\|(3),
220\&\fIDH_generate_parameters\fR\|(3),
221\&\fIDH_compute_key\fR\|(3), \fId2i_DHparams\fR\|(3),
aac4ff6f 222\&\fIRSA_print\fR\|(3)