openssl-dhparam - DH parameter manipulation and generation
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]
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.
- -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).
This command replaces the
dh and
gendh commands of previous
releases.
openssl(1),
openssl-pkeyparam(1),
openssl-dsaparam(1),
openssl-genpkey(1).
The
-engine option was deprecated in OpenSSL 3.0.
The
-C option was removed in OpenSSL 3.0.
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>.