6 genpkey - generate a private key
19 [B<-pkeyopt opt:value>]
25 The B<genpkey> command generates a private key.
33 Print out a usage message.
35 =item B<-out filename>
37 Output the key to the specified file. If this argument is not specified then
38 standard output is used.
40 =item B<-outform DER|PEM>
42 This specifies the output format DER or PEM. The default format is PEM.
46 The output file password source. For more information about the format of B<arg>
47 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
51 This option encrypts the private key with the supplied cipher. Any algorithm
52 name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>.
56 Specifying an engine (by its unique B<id> string) will cause B<genpkey>
57 to attempt to obtain a functional reference to the specified engine,
58 thus initialising it if needed. The engine will then be set as the default
59 for all available algorithms. If used this option should precede all other
62 =item B<-algorithm alg>
64 Public key algorithm to use such as RSA, DSA or DH. If used this option must
65 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
66 are mutually exclusive.
68 =item B<-pkeyopt opt:value>
70 Set the public key algorithm option B<opt> to B<value>. The precise set of
71 options supported depends on the public key algorithm used and its
72 implementation. See B<KEY GENERATION OPTIONS> below for more details.
76 Generate a set of parameters instead of a private key. If used this option must
77 precede any B<-algorithm>, B<-paramfile> or B<-pkeyopt> options.
79 =item B<-paramfile filename>
81 Some public key algorithms generate a private key based on a set of parameters.
82 They can be supplied using this option. If this option is used the public key
83 algorithm used is determined by the parameters. If used this option must
84 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
85 are mutually exclusive.
89 Print an (unencrypted) text representation of private and public keys and
90 parameters along with the PEM or DER structure.
94 =head1 KEY GENERATION OPTIONS
96 The options supported by each algorithm and indeed each implementation of an
97 algorithm can vary. The options for the OpenSSL implementations are detailed
100 =head1 RSA KEY GENERATION OPTIONS
104 =item B<rsa_keygen_bits:numbits>
106 The number of bits in the generated key. If not specified 1024 is used.
108 =item B<rsa_keygen_pubexp:value>
110 The RSA public exponent value. This can be a large decimal or
111 hexadecimal value if preceded by B<0x>. Default value is 65537.
115 =head1 RSA-PSS KEY GENERATION OPTIONS
117 Note: by default an B<RSA-PSS> key has no parameter restrictions.
121 =item B<rsa_keygen_bits:numbits>, B<rsa_keygen_pubexp:value>
123 These options have the same meaning as the B<RSA> algorithm.
125 =item B<rsa_pss_keygen_md:digest>
127 If set the key is restricted and can only use B<digest> for signing.
129 =item B<rsa_pss_keygen_mgf1_md:digest>
131 If set the key is restricted and can only use B<digest> as it's MGF1
134 =item B<rsa_pss_keygen_saltlen:len>
136 If set the key is restricted and B<len> specifies the minimum salt length.
140 =head1 DSA PARAMETER GENERATION OPTIONS
144 =item B<dsa_paramgen_bits:numbits>
146 The number of bits in the generated parameters. If not specified 1024 is used.
150 =head1 DH PARAMETER GENERATION OPTIONS
154 =item B<dh_paramgen_prime_len:numbits>
156 The number of bits in the prime parameter B<p>.
158 =item B<dh_paramgen_generator:value>
160 The value to use for the generator B<g>.
162 =item B<dh_rfc5114:num>
164 If this option is set then the appropriate RFC5114 parameters are used
165 instead of generating new parameters. The value B<num> can take the
166 values 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of
167 1024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup
168 and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections
169 2.1, 2.2 and 2.3 respectively.
173 =head1 EC PARAMETER GENERATION OPTIONS
175 The EC parameter generation options below can also
176 be supplied as EC key generation options. This can (for example) generate a
177 key from a named curve without the need to use an explicit parameter file.
181 =item B<ec_paramgen_curve:curve>
183 The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
185 =item B<ec_param_enc:encoding>
187 The encoding to use for parameters. The "encoding" parameter must be either
188 "named_curve" or "explicit".
192 =head1 GOST2001 KEY GENERATION AND PARAMETER OPTIONS
194 Gost 2001 support is not enabled by default. To enable this algorithm,
195 one should load the ccgost engine in the OpenSSL configuration file.
196 See README.gost file in the engines/ccgost directory of the source
197 distribution for more details.
199 Use of a parameter file for the GOST R 34.10 algorithm is optional.
200 Parameters can be specified during key generation directly as well as
201 during generation of parameter file.
205 =item B<paramset:name>
207 Specifies GOST R 34.10-2001 parameter set according to RFC 4357.
208 Parameter set can be specified using abbreviated name, object short name or
209 numeric OID. Following parameter sets are supported:
212 A 1.2.643.2.2.35.1 Signature
213 B 1.2.643.2.2.35.2 Signature
214 C 1.2.643.2.2.35.3 Signature
215 XA 1.2.643.2.2.36.0 Key exchange
216 XB 1.2.643.2.2.36.1 Key exchange
217 test 1.2.643.2.2.35.0 Test purposes
221 =head1 X25519 KEY GENERATION OPTIONS
223 The X25519 algorithm does not currently support any key generation options.
228 The use of the genpkey program is encouraged over the algorithm specific
229 utilities because additional algorithm options and ENGINE provided algorithms
234 Generate an RSA private key using default parameters:
236 openssl genpkey -algorithm RSA -out key.pem
238 Encrypt output private key using 128 bit AES and the passphrase "hello":
240 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
242 Generate a 2048 bit RSA key using 3 as the public exponent:
244 openssl genpkey -algorithm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048 \
245 -pkeyopt rsa_keygen_pubexp:3
247 Generate 1024 bit DSA parameters:
249 openssl genpkey -genparam -algorithm DSA -out dsap.pem \
250 -pkeyopt dsa_paramgen_bits:1024
252 Generate DSA key from parameters:
254 openssl genpkey -paramfile dsap.pem -out dsakey.pem
256 Generate 1024 bit DH parameters:
258 openssl genpkey -genparam -algorithm DH -out dhp.pem \
259 -pkeyopt dh_paramgen_prime_len:1024
261 Output RFC5114 2048 bit DH parameters with 224 bit subgroup:
263 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt dh_rfc5114:2
265 Generate DH key from parameters:
267 openssl genpkey -paramfile dhp.pem -out dhkey.pem
269 Generate EC parameters:
271 openssl genpkey -genparam -algorithm EC -out ecp.pem \
272 -pkeyopt ec_paramgen_curve:secp384r1 \
273 -pkeyopt ec_param_enc:named_curve
275 Generate EC key from parameters:
277 openssl genpkey -paramfile ecp.pem -out eckey.pem
279 Generate EC key directly:
281 openssl genpkey -algorithm EC -out eckey.pem \
282 -pkeyopt ec_paramgen_curve:P-384 \
283 -pkeyopt ec_param_enc:named_curve
285 Generate an X25519 private key:
287 openssl genpkey -algorithm X25519 -out xkey.pem
291 The ability to use NIST curve names, and to generate an EC key directly,
292 were added in OpenSSL 1.0.2.
296 Copyright 2006-2017 The OpenSSL Project Authors. All Rights Reserved.
298 Licensed under the OpenSSL license (the "License"). You may not use
299 this file except in compliance with the License. You can obtain a copy
300 in the file LICENSE in the source distribution or at
301 L<https://www.openssl.org/source/license.html>.