Update files for OpenSSL-1.0.0f import.
[dragonfly.git] / secure / lib / libcrypto / man / dh.3
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124.\" ========================================================================
125.\"
126.IX Title "dh 3"
e3261593 127.TH dh 3 "2012-01-04" "1.0.0f" "OpenSSL"
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128.\" For nroff, turn off justification. Always turn off hyphenation; it makes
129.\" way too many mistakes in technical documents.
130.if n .ad l
131.nh
984263bc 132.SH "NAME"
8b0cefbb 133dh \- Diffie\-Hellman key agreement
984263bc 134.SH "SYNOPSIS"
8b0cefbb 135.IX Header "SYNOPSIS"
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136.Vb 2
137\& #include <openssl/dh.h>
138\& #include <openssl/engine.h>
e257b235 139\&
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140\& DH * DH_new(void);
141\& void DH_free(DH *dh);
e257b235 142\&
984263bc 143\& int DH_size(const DH *dh);
e257b235 144\&
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145\& DH * DH_generate_parameters(int prime_len, int generator,
146\& void (*callback)(int, int, void *), void *cb_arg);
147\& int DH_check(const DH *dh, int *codes);
e257b235 148\&
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149\& int DH_generate_key(DH *dh);
150\& int DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh);
e257b235 151\&
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152\& void DH_set_default_method(const DH_METHOD *meth);
153\& const DH_METHOD *DH_get_default_method(void);
154\& int DH_set_method(DH *dh, const DH_METHOD *meth);
155\& DH *DH_new_method(ENGINE *engine);
156\& const DH_METHOD *DH_OpenSSL(void);
e257b235 157\&
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158\& int DH_get_ex_new_index(long argl, char *argp, int (*new_func)(),
159\& int (*dup_func)(), void (*free_func)());
160\& int DH_set_ex_data(DH *d, int idx, char *arg);
161\& char *DH_get_ex_data(DH *d, int idx);
e257b235 162\&
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163\& DH * d2i_DHparams(DH **a, unsigned char **pp, long length);
164\& int i2d_DHparams(const DH *a, unsigned char **pp);
e257b235 165\&
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166\& int DHparams_print_fp(FILE *fp, const DH *x);
167\& int DHparams_print(BIO *bp, const DH *x);
168.Ve
169.SH "DESCRIPTION"
8b0cefbb 170.IX Header "DESCRIPTION"
984263bc 171These functions implement the Diffie-Hellman key agreement protocol.
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172The generation of shared \s-1DH\s0 parameters is described in
173\&\fIDH_generate_parameters\fR\|(3); \fIDH_generate_key\fR\|(3) describes how
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174to perform a key agreement.
175.PP
8b0cefbb 176The \fB\s-1DH\s0\fR structure consists of several \s-1BIGNUM\s0 components.
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177.PP
178.Vb 9
179\& struct
180\& {
181\& BIGNUM *p; // prime number (shared)
182\& BIGNUM *g; // generator of Z_p (shared)
183\& BIGNUM *priv_key; // private DH value x
184\& BIGNUM *pub_key; // public DH value g^x
185\& // ...
186\& };
187\& DH
188.Ve
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189.PP
190Note that \s-1DH\s0 keys may use non-standard \fB\s-1DH_METHOD\s0\fR implementations,
191either directly or by the use of \fB\s-1ENGINE\s0\fR modules. In some cases (eg. an
192\&\s-1ENGINE\s0 providing support for hardware-embedded keys), these \s-1BIGNUM\s0 values
984263bc 193will not be used by the implementation or may be used for alternative data
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194storage. For this reason, applications should generally avoid using \s-1DH\s0
195structure elements directly and instead use \s-1API\s0 functions to query or
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196modify keys.
197.SH "SEE ALSO"
74dab6c2 198.IX Header "SEE ALSO"
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199\&\fIdhparam\fR\|(1), \fIbn\fR\|(3), \fIdsa\fR\|(3), \fIerr\fR\|(3),
200\&\fIrand\fR\|(3), \fIrsa\fR\|(3), \fIengine\fR\|(3),
201\&\fIDH_set_method\fR\|(3), \fIDH_new\fR\|(3),
202\&\fIDH_get_ex_new_index\fR\|(3),
203\&\fIDH_generate_parameters\fR\|(3),
204\&\fIDH_compute_key\fR\|(3), \fId2i_DHparams\fR\|(3),
e257b235 205\&\fIRSA_print\fR\|(3)