1OPENSSL-DHPARAM(1ossl) OpenSSL OPENSSL-DHPARAM(1ossl)
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6 openssl-dhparam - DH parameter manipulation and generation
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9 openssl dhparam [-help] [-inform DER|PEM] [-outform DER|PEM] [-in
10 filename] [-out filename] [-dsaparam] [-check] [-noout] [-text] [-2]
11 [-3] [-5] [-engine id] [-rand files] [-writerand file] [-provider name]
12 [-provider-path path] [-propquery propq] [numbits]
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15 This command is used to manipulate DH parameter files.
16 See "EXAMPLES" in openssl-genpkey(1) for examples on how to generate a
18 key using a named safe prime group without generating intermediate
19 parameters.
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22 -help
23 Print out a usage message.
24 -inform DER|PEM, -outform DER|PEM
26 The input format and output format; the default is PEM. The object
27 is compatible with the PKCS#3 DHparameter structure. See
28 openssl-format-options(1) for details.
29 -in filename
31 This specifies the input filename to read parameters from or
32 standard input if this option is not specified.
33 -out filename
35 This specifies the output filename parameters to. Standard output
36 is used if this option is not present. The output filename should
37 not be the same as the input filename.
38 -dsaparam
40 If this option is used, DSA rather than DH parameters are read or
41 created; they are converted to DH format. Otherwise, "strong"
42 primes (such that (p-1)/2 is also prime) will be used for DH
43 parameter generation.
44 DH parameter generation with the -dsaparam option is much faster,
46 and the recommended exponent length is shorter, which makes DH key
47 exchange more efficient. Beware that with such DSA-style DH
48 parameters, a fresh DH key should be created for each use to avoid
49 small-subgroup attacks that may be possible otherwise.
50 -check
52 Performs numerous checks to see if the supplied parameters are
53 valid and displays a warning if not.
54 -2, -3, -5
56 The generator to use, either 2, 3 or 5. If present then the input
57 file is ignored and parameters are generated instead. If not
58 present but numbits is present, parameters are generated with the
59 default generator 2.
60 numbits
62 This option specifies that a parameter set should be generated of
63 size numbits. It must be the last option. If this option is present
64 then the input file is ignored and parameters are generated
65 instead. If this option is not present but a generator (-2, -3 or
66 -5) is present, parameters are generated with a default length of
67 2048 bits. The minimim length is 512 bits. The maximum length is
68 10000 bits.
69 -noout
71 This option inhibits the output of the encoded version of the
72 parameters.
73 -text
75 This option prints out the DH parameters in human readable form.
76 -engine id
78 See "Engine Options" in openssl(1). This option is deprecated.
79 -rand files, -writerand file
81 See "Random State Options" in openssl(1) for details.
82 -provider name
84 -provider-path path
85 -propquery propq
86 See "Provider Options" in openssl(1), provider(7), and property(7).
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89 This command replaces the dh and gendh commands of previous releases.
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92 openssl(1), openssl-pkeyparam(1), openssl-dsaparam(1),
93 openssl-genpkey(1).
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96 The -engine option was deprecated in OpenSSL 3.0.
97 The -C option was removed in OpenSSL 3.0.
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101 Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
102 Licensed under the Apache License 2.0 (the "License"). You may not use
104 this file except in compliance with the License. You can obtain a copy
105 in the file LICENSE in the source distribution or at
106 <https://www.openssl.org/source/license.html>.
1073.0.9 2023-07-27 OPENSSL-DHPARAM(1ossl)