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Editing: DH_compute_key.3
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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" DH_generate_key, DH_compute_key \- perform Diffie\-Hellman key exchange .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/dh.h> \& \& int DH_generate_key(DH *dh); \& \& int DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\fBDH_generate_key()\fR performs the first step of a Diffie-Hellman key exchange by generating private and public \s-1DH\s0 values. By calling \&\fBDH_compute_key()\fR, these are combined with the other party's public value to compute the shared key. .PP \&\fBDH_generate_key()\fR expects \fBdh\fR to contain the shared parameters \&\fBdh\->p\fR and \fBdh\->g\fR. It generates a random private \s-1DH\s0 value unless \fBdh\->priv_key\fR is already set, and computes the corresponding public value \fBdh\->pub_key\fR, which can then be published. .PP \&\fBDH_compute_key()\fR computes the shared secret from the private \s-1DH\s0 value in \fBdh\fR and the other party's public value in \fBpub_key\fR and stores it in \fBkey\fR. \fBkey\fR must point to \fBDH_size(dh)\fR bytes of memory. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBDH_generate_key()\fR returns 1 on success, 0 otherwise. .PP \&\fBDH_compute_key()\fR returns the size of the shared secret on success, \-1 on error. .PP The error codes can be obtained by \fBERR_get_error\fR\|(3). .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBdh\fR\|(3), \fBERR_get_error\fR\|(3), \fBrand\fR\|(3), \fBDH_size\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" \&\fBDH_generate_key()\fR and \fBDH_compute_key()\fR are available in all versions of SSLeay and OpenSSL.
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