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.\" Thu May 9 13:17:01 2002
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.\" ======================================================================
.\"
.IX Title "DH_SET_METHOD 1"
.TH DH_SET_METHOD 1 "perl v5.6.1" "2000-11-13" "User Contributed Perl Documentation"
.UC
.SH "NAME"
DH_set_default_method, DH_get_default_method, DH_set_method,
DH_new_method, DH_OpenSSL \- select \s-1DH\s0 method
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/dh.h>
.Ve
.Vb 1
\& void DH_set_default_method(DH_METHOD *meth);
.Ve
.Vb 1
\& DH_METHOD *DH_get_default_method(void);
.Ve
.Vb 1
\& DH_METHOD *DH_set_method(DH *dh, DH_METHOD *meth);
.Ve
.Vb 1
\& DH *DH_new_method(DH_METHOD *meth);
.Ve
.Vb 1
\& DH_METHOD *DH_OpenSSL(void);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
A \fB\s-1DH_METHOD\s0\fR specifies the functions that OpenSSL uses for Diffie-Hellman
operations. By modifying the method, alternative implementations
such as hardware accelerators may be used.
.PP
Initially, the default is to use the OpenSSL internal implementation.
\&\fIDH_OpenSSL()\fR returns a pointer to that method.
.PP
\&\fIDH_set_default_method()\fR makes \fBmeth\fR the default method for all \fB\s-1DH\s0\fR
structures created later.
.PP
\&\fIDH_get_default_method()\fR returns a pointer to the current default
method.
.PP
\&\fIDH_set_method()\fR selects \fBmeth\fR for all operations using the structure \fBdh\fR.
.PP
\&\fIDH_new_method()\fR allocates and initializes a \fB\s-1DH\s0\fR structure so that
\&\fBmethod\fR will be used for the \s-1DH\s0 operations. If \fBmethod\fR is \fB\s-1NULL\s0\fR,
the default method is used.
.SH "THE DH_METHOD STRUCTURE"
.IX Header "THE DH_METHOD STRUCTURE"
.Vb 4
\& typedef struct dh_meth_st
\& {
\& /* name of the implementation */
\& const char *name;
.Ve
.Vb 2
\& /* generate private and public DH values for key agreement */
\& int (*generate_key)(DH *dh);
.Ve
.Vb 2
\& /* compute shared secret */
\& int (*compute_key)(unsigned char *key, BIGNUM *pub_key, DH *dh);
.Ve
.Vb 4
\& /* compute r = a ^ p mod m (May be NULL for some implementations) */
\& int (*bn_mod_exp)(DH *dh, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
\& const BIGNUM *m, BN_CTX *ctx,
\& BN_MONT_CTX *m_ctx);
.Ve
.Vb 2
\& /* called at DH_new */
\& int (*init)(DH *dh);
.Ve
.Vb 2
\& /* called at DH_free */
\& int (*finish)(DH *dh);
.Ve
.Vb 1
\& int flags;
.Ve
.Vb 1
\& char *app_data; /* ?? */
.Ve
.Vb 1
\& } DH_METHOD;
.Ve
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIDH_OpenSSL()\fR and \fIDH_get_default_method()\fR return pointers to the respective
\&\fB\s-1DH_METHOD\s0\fRs.
.PP
\&\fIDH_set_default_method()\fR returns no value.
.PP
\&\fIDH_set_method()\fR returns a pointer to the \fB\s-1DH_METHOD\s0\fR previously
associated with \fBdh\fR.
.PP
\&\fIDH_new_method()\fR returns \fB\s-1NULL\s0\fR and sets an error code that can be
obtained by ERR_get_error(3) if the allocation fails. Otherwise it
returns a pointer to the newly allocated structure.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
dh(3), DH_new(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fIDH_set_default_method()\fR, \fIDH_get_default_method()\fR, \fIDH_set_method()\fR,
\&\fIDH_new_method()\fR and \fIDH_OpenSSL()\fR were added in OpenSSL 0.9.4.
|
