Provided by: openssl_3.0.13-0ubuntu3.5_amd64 bug

NAME
       openssl-dhparam - DH parameter manipulation and generation


SYNOPSIS
       openssl dhparam [-help] [-inform DER|PEM] [-outform DER|PEM] [-in filename] [-out filename] [-dsaparam]
       [-check] [-noout] [-text] [-2] [-3] [-5] [-engine id] [-rand files] [-writerand file] [-provider name]
       [-provider-path path] [-propquery propq] [numbits]


DESCRIPTION
       This command is used to manipulate DH parameter files.

       See "EXAMPLES" in openssl-genpkey(1) for examples on how to generate a key using a named safe prime group
       without generating intermediate parameters.


OPTIONS
       -help
           Print out a usage message.

       -inform DER|PEM, -outform DER|PEM
           The  input  format  and  output format; the default is PEM.  The object is compatible with the PKCS#3
           DHparameter structure.  See openssl-format-options(1) for details.

       -in filename
           This specifies the input filename to read parameters from or standard input if  this  option  is  not
           specified.

       -out filename
           This  specifies  the  output  filename  parameters  to. Standard output is used if this option is not
           present. The output filename should not be the same as the input filename.

       -dsaparam
           If this option is used, DSA rather than DH parameters are read or created; they are converted  to  DH
           format.   Otherwise,  "strong" primes (such that (p-1)/2 is also prime) will be used for DH parameter
           generation.

           DH parameter generation with the -dsaparam option is much faster, and the recommended exponent length
           is shorter, which makes DH  key  exchange  more  efficient.   Beware  that  with  such  DSA-style  DH
           parameters, a fresh DH key should be created for each use to avoid small-subgroup attacks that may be
           possible otherwise.

       -check
           Performs numerous checks to see if the supplied parameters are valid and displays a warning if not.

       -2, -3, -5
           The  generator to use, either 2, 3 or 5. If present then the input file is ignored and parameters are
           generated instead. If not present but numbits is present, parameters are generated with  the  default
           generator 2.

       numbits
           This  option  specifies that a parameter set should be generated of size numbits. 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 (-2, -3 or -5) is present, parameters are
           generated with a default length of 2048 bits.  The minimum length is 512 bits. The maximum length  is
           10000 bits.

       -noout
           This option inhibits the output of the encoded version of the parameters.

       -text
           This option prints out the DH parameters in human readable form.

       -engine id
           See "Engine Options" in openssl(1).  This option is deprecated.

       -rand files, -writerand file
           See "Random State Options" in openssl(1) for details.

       -provider name
       -provider-path path
       -propquery propq
           See "Provider Options" in openssl(1), provider(7), and property(7).


NOTES
       This command replaces the dh and gendh commands of previous releases.


SEE ALSO
       openssl(1), openssl-pkeyparam(1), openssl-dsaparam(1), openssl-genpkey(1).


HISTORY
       The -engine option was deprecated in OpenSSL 3.0.

       The -C option was removed in OpenSSL 3.0.


COPYRIGHT
       Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.

       Licensed  under  the  Apache License 2.0 (the "License").  You may not use this file except in compliance
       with the License.  You can obtain  a  copy  in  the  file  LICENSE  in  the  source  distribution  or  at
       <https://www.openssl.org/source/license.html>.

3.0.13                                             2025-02-05                              OPENSSL-DHPARAM(1SSL)