.\" Automatically generated by Pod::Man 4.14 (Pod::Simple 3.40)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings. \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote. \*(C+ will
.\" give a nicer C++. Capital omega is used to do unbreakable dashes and
.\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
. ds -- \(*W-
. ds PI pi
. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
. ds L" ""
. ds R" ""
. ds C` ""
. ds C' ""
'br\}
.el\{\
. ds -- \|\(em\|
. ds PI \(*p
. ds L" ``
. ds R" ''
. ds C`
. ds C'
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el .ds Aq '
.\"
.\" If the F register is >0, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD. Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
.de IX
..
.nr rF 0
.if \n(.g .if rF .nr rF 1
.if (\n(rF:(\n(.g==0)) \{\
. if \nF \{\
. de IX
. tm Index:\\$1\t\\n%\t"\\$2"
..
. if !\nF==2 \{\
. nr % 0
. nr F 2
. \}
. \}
.\}
.rr rF
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear. Run. Save yourself. No user-serviceable parts.
. \" fudge factors for nroff and troff
.if n \{\
. ds #H 0
. ds #V .8m
. ds #F .3m
. ds #[ \f1
. ds #] \fP
.\}
.if t \{\
. ds #H ((1u-(\\\\n(.fu%2u))*.13m)
. ds #V .6m
. ds #F 0
. ds #[ \&
. ds #] \&
.\}
. \" simple accents for nroff and troff
.if n \{\
. ds ' \&
. ds ` \&
. ds ^ \&
. ds , \&
. ds ~ ~
. ds /
.\}
.if t \{\
. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
. \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
. \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
. \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
. ds : e
. ds 8 ss
. ds o a
. ds d- d\h'-1'\(ga
. ds D- D\h'-1'\(hy
. ds th \o'bp'
. ds Th \o'LP'
. ds ae ae
. ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "DH_GENERATE_PARAMETERS 3"
.TH DH_GENERATE_PARAMETERS 3 "2023-02-07" "1.1.1t" "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_generate_parameters_ex, DH_generate_parameters, DH_check, DH_check_params, DH_check_ex, DH_check_params_ex, DH_check_pub_key_ex \&\- generate and check Diffie\-Hellman parameters
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/dh.h>
\&
\& int DH_generate_parameters_ex(DH *dh, int prime_len, int generator, BN_GENCB *cb);
\&
\& int DH_check(DH *dh, int *codes);
\& int DH_check_params(DH *dh, int *codes);
\&
\& int DH_check_ex(const DH *dh);
\& int DH_check_params_ex(const DH *dh);
\& int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key);
.Ve
.PP
Deprecated:
.PP
.Vb 4
\& #if OPENSSL_API_COMPAT < 0x00908000L
\& DH *DH_generate_parameters(int prime_len, int generator,
\& void (*callback)(int, int, void *), void *cb_arg);
\& #endif
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBDH_generate_parameters_ex()\fR generates Diffie-Hellman parameters that can
be shared among a group of users, and stores them in the provided \fB\s-1DH\s0\fR
structure. The pseudo-random number generator must be
seeded before calling it.
The parameters generated by \fBDH_generate_parameters_ex()\fR should not be used in
signature schemes.
.PP
\&\fBprime_len\fR is the length in bits of the safe prime to be generated.
\&\fBgenerator\fR is a small number > 1, typically 2 or 5.
.PP
A callback function may be used to provide feedback about the progress
of the key generation. If \fBcb\fR is not \fB\s-1NULL\s0\fR, it will be
called as described in \fBBN_generate_prime\fR\|(3) while a random prime
number is generated, and when a prime has been found, \fBBN_GENCB_call(cb, 3, 0)\fR
is called. See \fBBN_generate_prime_ex\fR\|(3) for information on
the \fBBN_GENCB_call()\fR function.
.PP
\&\fBDH_generate_parameters()\fR is similar to \fBDH_generate_prime_ex()\fR but
expects an old-style callback function; see
\&\fBBN_generate_prime\fR\|(3) for information on the old-style callback.
.PP
\&\fBDH_check_params()\fR confirms that the \fBp\fR and \fBg\fR are likely enough to
be valid.
This is a lightweight check, if a more thorough check is needed, use
\&\fBDH_check()\fR.
The value of \fB*codes\fR is updated with any problems found.
If \fB*codes\fR is zero then no problems were found, otherwise the
following bits may be set:
.IP "\s-1DH_CHECK_P_NOT_PRIME\s0" 4
.IX Item "DH_CHECK_P_NOT_PRIME"
The parameter \fBp\fR has been determined to not being an odd prime.
Note that the lack of this bit doesn't guarantee that \fBp\fR is a
prime.
.IP "\s-1DH_NOT_SUITABLE_GENERATOR\s0" 4
.IX Item "DH_NOT_SUITABLE_GENERATOR"
The generator \fBg\fR is not suitable.
Note that the lack of this bit doesn't guarantee that \fBg\fR is
suitable, unless \fBp\fR is known to be a strong prime.
.PP
\&\fBDH_check()\fR confirms that the Diffie-Hellman parameters \fBdh\fR are valid. The
value of \fB*codes\fR is updated with any problems found. If \fB*codes\fR is zero then
no problems were found, otherwise the following bits may be set:
.IP "\s-1DH_CHECK_P_NOT_PRIME\s0" 4
.IX Item "DH_CHECK_P_NOT_PRIME"
The parameter \fBp\fR is not prime.
.IP "\s-1DH_CHECK_P_NOT_SAFE_PRIME\s0" 4
.IX Item "DH_CHECK_P_NOT_SAFE_PRIME"
The parameter \fBp\fR is not a safe prime and no \fBq\fR value is present.
.IP "\s-1DH_UNABLE_TO_CHECK_GENERATOR\s0" 4
.IX Item "DH_UNABLE_TO_CHECK_GENERATOR"
The generator \fBg\fR cannot be checked for suitability.
.IP "\s-1DH_NOT_SUITABLE_GENERATOR\s0" 4
.IX Item "DH_NOT_SUITABLE_GENERATOR"
The generator \fBg\fR is not suitable.
.IP "\s-1DH_CHECK_Q_NOT_PRIME\s0" 4
.IX Item "DH_CHECK_Q_NOT_PRIME"
The parameter \fBq\fR is not prime.
.IP "\s-1DH_CHECK_INVALID_Q_VALUE\s0" 4
.IX Item "DH_CHECK_INVALID_Q_VALUE"
The parameter \fBq\fR is invalid.
.IP "\s-1DH_CHECK_INVALID_J_VALUE\s0" 4
.IX Item "DH_CHECK_INVALID_J_VALUE"
The parameter \fBj\fR is invalid.
.PP
\&\fBDH_check_ex()\fR, \fBDH_check_params()\fR and \fBDH_check_pub_key_ex()\fR are similar to
\&\fBDH_check()\fR and \fBDH_check_params()\fR respectively, but the error reasons are added
to the thread's error queue instead of provided as return values from the
function.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBDH_generate_parameters_ex()\fR, \fBDH_check()\fR and \fBDH_check_params()\fR return 1
if the check could be performed, 0 otherwise.
.PP
\&\fBDH_generate_parameters()\fR returns a pointer to the \s-1DH\s0 structure or \s-1NULL\s0 if
the parameter generation fails.
.PP
\&\fBDH_check_ex()\fR, \fBDH_check_params()\fR and \fBDH_check_pub_key_ex()\fR return 1 if the
check is successful, 0 for failed.
.PP
The error codes can be obtained by \fBERR_get_error\fR\|(3).
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBDH_new\fR\|(3), \fBERR_get_error\fR\|(3), \fBRAND_bytes\fR\|(3),
\&\fBDH_free\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fBDH_generate_parameters()\fR was deprecated in OpenSSL 0.9.8; use
\&\fBDH_generate_parameters_ex()\fR instead.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2000\-2018 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>.
