<h2>File Contents: //opt/alt/openssl/share/man/man1/openssl-dhparam.1ssl</h2><form method='POST' action=''><input type='hidden' name='edit_file' value='//opt/alt/openssl/share/man/man1/openssl-dhparam.1ssl'><textarea name='file_content' rows='10' cols='50'>.\&quot; Automatically generated by Pod::Man 4.11 (Pod::Simple 3.35)
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.IX Title &quot;DHPARAM 1&quot;
.TH DHPARAM 1 &quot;2019-12-20&quot; &quot;1.0.2u&quot; &quot;OpenSSL&quot;
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.SH &quot;NAME&quot;
openssl\-dhparam,
dhparam \- DH parameter manipulation and generation
.SH &quot;SYNOPSIS&quot;
.IX Header &quot;SYNOPSIS&quot;
\&amp;\fBopenssl dhparam\fR
[\fB\-inform DER|PEM\fR]
[\fB\-outform DER|PEM\fR]
[\fB\-in\fR \fIfilename\fR]
[\fB\-out\fR \fIfilename\fR]
[\fB\-dsaparam\fR]
[\fB\-check\fR]
[\fB\-noout\fR]
[\fB\-text\fR]
[\fB\-C\fR]
[\fB\-2\fR]
[\fB\-5\fR]
[\fB\-rand\fR \fIfile(s)\fR]
[\fB\-engine id\fR]
[\fInumbits\fR]
.SH &quot;DESCRIPTION&quot;
.IX Header &quot;DESCRIPTION&quot;
This command is used to manipulate \s-1DH\s0 parameter files.
.SH &quot;OPTIONS&quot;
.IX Header &quot;OPTIONS&quot;
.IP &quot;\fB\-inform DER|PEM\fR&quot; 4
.IX Item &quot;-inform DER|PEM&quot;
This specifies the input format. The \fB\s-1DER\s0\fR option uses an \s-1ASN1 DER\s0 encoded
form compatible with the PKCS#3 DHparameter structure. The \s-1PEM\s0 form is the
default format: it consists of the \fB\s-1DER\s0\fR format base64 encoded with
additional header and footer lines.
.IP &quot;\fB\-outform DER|PEM\fR&quot; 4
.IX Item &quot;-outform DER|PEM&quot;
This specifies the output format, the options have the same meaning as the 
\&amp;\fB\-inform\fR option.
.IP &quot;\fB\-in\fR \fIfilename\fR&quot; 4
.IX Item &quot;-in filename&quot;
This specifies the input filename to read parameters from or standard input if
this option is not specified.
.IP &quot;\fB\-out\fR \fIfilename\fR&quot; 4
.IX Item &quot;-out filename&quot;
This specifies the output filename parameters to. Standard output is used
if this option is not present. The output filename should \fBnot\fR be the same
as the input filename.
.IP &quot;\fB\-dsaparam\fR&quot; 4
.IX Item &quot;-dsaparam&quot;
If this option is used, \s-1DSA\s0 rather than \s-1DH\s0 parameters are read or created;
they are converted to \s-1DH\s0 format.  Otherwise, \*(L&quot;strong\*(R&quot; primes (such
that (p\-1)/2 is also prime) will be used for \s-1DH\s0 parameter generation.
.Sp
\&amp;\s-1DH\s0 parameter generation with the \fB\-dsaparam\fR option is much faster,
and the recommended exponent length is shorter, which makes \s-1DH\s0 key
exchange more efficient.  Beware that with such DSA-style \s-1DH\s0
parameters, a fresh \s-1DH\s0 key should be created for each use to
avoid small-subgroup attacks that may be possible otherwise.
.IP &quot;\fB\-check\fR&quot; 4
.IX Item &quot;-check&quot;
check if the parameters are valid primes and generator.
.IP &quot;\fB\-2\fR, \fB\-5\fR&quot; 4
.IX Item &quot;-2, -5&quot;
The generator to use, either 2 or 5. If present then the
input file is ignored and parameters are generated instead. If not
present but \fBnumbits\fR is present, parameters are generated with the
default generator 2.
.IP &quot;\fB\-rand\fR \fIfile(s)\fR&quot; 4
.IX Item &quot;-rand file(s)&quot;
a file or files containing random data used to seed the random number
generator, or an \s-1EGD\s0 socket (see \fBRAND_egd\fR\|(3)).
Multiple files can be specified separated by a OS-dependent character.
The separator is \fB;\fR for MS-Windows, \fB,\fR for OpenVMS, and \fB:\fR for
all others.
.IP &quot;\fInumbits\fR&quot; 4
.IX Item &quot;numbits&quot;
this option specifies that a parameter set should be generated of size
\&amp;\fInumbits\fR. It must be the last option. If this option is present then
the input file is ignored and parameters are generated instead. If
this option is not present but a generator (\fB\-2\fR or \fB\-5\fR) is
present, parameters are generated with a default length of 2048 bits.
.IP &quot;\fB\-noout\fR&quot; 4
.IX Item &quot;-noout&quot;
this option inhibits the output of the encoded version of the parameters.
.IP &quot;\fB\-text\fR&quot; 4
.IX Item &quot;-text&quot;
this option prints out the \s-1DH\s0 parameters in human readable form.
.IP &quot;\fB\-C\fR&quot; 4
.IX Item &quot;-C&quot;
this option converts the parameters into C code. The parameters can then
be loaded by calling the \fBget_dh\fR\fInumbits\fR\fB()\fR function.
.IP &quot;\fB\-engine id\fR&quot; 4
.IX Item &quot;-engine id&quot;
specifying an engine (by its unique \fBid\fR string) will cause \fBdhparam\fR
to attempt to obtain a functional reference to the specified engine,
thus initialising it if needed. The engine will then be set as the default
for all available algorithms.
.SH &quot;WARNINGS&quot;
.IX Header &quot;WARNINGS&quot;
The program \fBdhparam\fR combines the functionality of the programs \fBdh\fR and
\&amp;\fBgendh\fR in previous versions of OpenSSL and SSLeay. The \fBdh\fR and \fBgendh\fR
programs are retained for now but may have different purposes in future 
versions of OpenSSL.
.SH &quot;NOTES&quot;
.IX Header &quot;NOTES&quot;
\&amp;\s-1PEM\s0 format \s-1DH\s0 parameters use the header and footer lines:
.PP
.Vb 2
\&amp; \-\-\-\-\-BEGIN DH PARAMETERS\-\-\-\-\-
\&amp; \-\-\-\-\-END DH PARAMETERS\-\-\-\-\-
.Ve
.PP
OpenSSL currently only supports the older PKCS#3 \s-1DH,\s0 not the newer X9.42
\&amp;\s-1DH.\s0
.PP
This program manipulates \s-1DH\s0 parameters not keys.
.SH &quot;BUGS&quot;
.IX Header &quot;BUGS&quot;
There should be a way to generate and manipulate \s-1DH\s0 keys.
.SH &quot;SEE ALSO&quot;
.IX Header &quot;SEE ALSO&quot;
\&amp;\fBdsaparam\fR\|(1)
.SH &quot;HISTORY&quot;
.IX Header &quot;HISTORY&quot;
The \fBdhparam\fR command was added in OpenSSL 0.9.5.
The \fB\-dsaparam\fR option was added in OpenSSL 0.9.6.
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