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✏️ Editing: DH_get0_pqg.3

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.\" ========================================================================
.\"
.IX Title "DH_GET0_PQG 3"
.TH DH_GET0_PQG 3 "2023-09-11" "1.1.1w" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
DH_get0_pqg, DH_set0_pqg, DH_get0_key, DH_set0_key, DH_get0_p, DH_get0_q, DH_get0_g, DH_get0_priv_key, DH_get0_pub_key, DH_clear_flags, DH_test_flags, DH_set_flags, DH_get0_engine, DH_get_length, DH_set_length \- Routines for getting and setting data in a DH object
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/dh.h>
\&
\& void DH_get0_pqg(const DH *dh,
\&                  const BIGNUM **p, const BIGNUM **q, const BIGNUM **g);
\& int DH_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g);
\& void DH_get0_key(const DH *dh,
\&                  const BIGNUM **pub_key, const BIGNUM **priv_key);
\& int DH_set0_key(DH *dh, BIGNUM *pub_key, BIGNUM *priv_key);
\& const BIGNUM *DH_get0_p(const DH *dh);
\& const BIGNUM *DH_get0_q(const DH *dh);
\& const BIGNUM *DH_get0_g(const DH *dh);
\& const BIGNUM *DH_get0_priv_key(const DH *dh);
\& const BIGNUM *DH_get0_pub_key(const DH *dh);
\& void DH_clear_flags(DH *dh, int flags);
\& int DH_test_flags(const DH *dh, int flags);
\& void DH_set_flags(DH *dh, int flags);
\& ENGINE *DH_get0_engine(DH *d);
\& long DH_get_length(const DH *dh);
\& int DH_set_length(DH *dh, long length);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
A \s-1DH\s0 object contains the parameters \fBp\fR, \fBq\fR and \fBg\fR. Note that the \fBq\fR
parameter is optional. It also contains a public key (\fBpub_key\fR) and
(optionally) a private key (\fBpriv_key\fR).
.PP
The \fBp\fR, \fBq\fR and \fBg\fR parameters can be obtained by calling \fBDH_get0_pqg()\fR.
If the parameters have not yet been set then \fB*p\fR, \fB*q\fR and \fB*g\fR will be set
to \s-1NULL.\s0 Otherwise they are set to pointers to their respective values. These
point directly to the internal representations of the values and therefore
should not be freed directly.
Any of the out parameters \fBp\fR, \fBq\fR, and \fBg\fR can be \s-1NULL,\s0 in which case no
value will be returned for that parameter.
.PP
The \fBp\fR, \fBq\fR and \fBg\fR values can be set by calling \fBDH_set0_pqg()\fR and passing
the new values for \fBp\fR, \fBq\fR and \fBg\fR as parameters to the function. Calling
this function transfers the memory management of the values to the \s-1DH\s0 object,
and therefore the values that have been passed in should not be freed directly
after this function has been called. The \fBq\fR parameter may be \s-1NULL.\s0
.PP
To get the public and private key values use the \fBDH_get0_key()\fR function. A
pointer to the public key will be stored in \fB*pub_key\fR, and a pointer to the
private key will be stored in \fB*priv_key\fR. Either may be \s-1NULL\s0 if they have not
been set yet, although if the private key has been set then the public key must
be. The values point to the internal representation of the public key and
private key values. This memory should not be freed directly.
Any of the out parameters \fBpub_key\fR and \fBpriv_key\fR can be \s-1NULL,\s0 in which case
no value will be returned for that parameter.
.PP
The public and private key values can be set using \fBDH_set0_key()\fR. Either
parameter may be \s-1NULL,\s0 which means the corresponding \s-1DH\s0 field is left
untouched. As with \fBDH_set0_pqg()\fR this function transfers the memory management
of the key values to the \s-1DH\s0 object, and therefore they should not be freed
directly after this function has been called.
.PP
Any of the values \fBp\fR, \fBq\fR, \fBg\fR, \fBpriv_key\fR, and \fBpub_key\fR can also be
retrieved separately by the corresponding function \fBDH_get0_p()\fR, \fBDH_get0_q()\fR,
\&\fBDH_get0_g()\fR, \fBDH_get0_priv_key()\fR, and \fBDH_get0_pub_key()\fR, respectively.
.PP
\&\fBDH_set_flags()\fR sets the flags in the \fBflags\fR parameter on the \s-1DH\s0 object.
Multiple flags can be passed in one go (bitwise ORed together). Any flags that
are already set are left set. \fBDH_test_flags()\fR tests to see whether the flags
passed in the \fBflags\fR parameter are currently set in the \s-1DH\s0 object. Multiple
flags can be tested in one go. All flags that are currently set are returned, or
zero if none of the flags are set. \fBDH_clear_flags()\fR clears the specified flags
within the \s-1DH\s0 object.
.PP
\&\fBDH_get0_engine()\fR returns a handle to the \s-1ENGINE\s0 that has been set for this \s-1DH\s0
object, or \s-1NULL\s0 if no such \s-1ENGINE\s0 has been set.
.PP
The \fBDH_get_length()\fR and \fBDH_set_length()\fR functions get and set the optional
length parameter associated with this \s-1DH\s0 object. If the length is nonzero then
it is used, otherwise it is ignored. The \fBlength\fR parameter indicates the
length of the secret exponent (private key) in bits.
.SH "NOTES"
.IX Header "NOTES"
Values retrieved with \fBDH_get0_key()\fR are owned by the \s-1DH\s0 object used
in the call and may therefore \fInot\fR be passed to \fBDH_set0_key()\fR.  If
needed, duplicate the received value using \fBBN_dup()\fR and pass the
duplicate.  The same applies to \fBDH_get0_pqg()\fR and \fBDH_set0_pqg()\fR.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBDH_set0_pqg()\fR and \fBDH_set0_key()\fR return 1 on success or 0 on failure.
.PP
\&\fBDH_get0_p()\fR, \fBDH_get0_q()\fR, \fBDH_get0_g()\fR, \fBDH_get0_priv_key()\fR, and \fBDH_get0_pub_key()\fR
return the respective value, or \s-1NULL\s0 if it is unset.
.PP
\&\fBDH_test_flags()\fR returns the current state of the flags in the \s-1DH\s0 object.
.PP
\&\fBDH_get0_engine()\fR returns the \s-1ENGINE\s0 set for the \s-1DH\s0 object or \s-1NULL\s0 if no \s-1ENGINE\s0
has been set.
.PP
\&\fBDH_get_length()\fR returns the length of the secret exponent (private key) in bits,
or zero if no such length has been explicitly set.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBDH_new\fR\|(3), \fBDH_new\fR\|(3), \fBDH_generate_parameters\fR\|(3), \fBDH_generate_key\fR\|(3),
\&\fBDH_set_method\fR\|(3), \fBDH_size\fR\|(3), \fBDH_meth_new\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
The functions described here were added in OpenSSL 1.1.0.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2016\-2020 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the OpenSSL license (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.

MR SKB