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_primes:numprimes>
110 The number of primes in the generated key. If not specified 2 is used.
112 =item B<rsa_keygen_pubexp:value>
114 The RSA public exponent value. This can be a large decimal or
115 hexadecimal value if preceded by B<0x>. Default value is 65537.
119 =head1 RSA-PSS KEY GENERATION OPTIONS
121 Note: by default an B<RSA-PSS> key has no parameter restrictions.
125 =item B<rsa_keygen_bits:numbits>, B<rsa_keygen_pubexp:value>
127 These options have the same meaning as the B<RSA> algorithm.
129 =item B<rsa_pss_keygen_md:digest>
131 =item B<rsa_keygen_pubexp:value>
133 The RSA public exponent value. This can be a large decimal or
134 hexadecimal value if preceded by B<0x>. Default value is 65537.
138 =head1 RSA-PSS KEY GENERATION OPTIONS
140 Note: by default an B<RSA-PSS> key has no parameter restrictions.
144 =item B<rsa_keygen_bits:numbits>, B<rsa_keygen_pubexp:value>
146 These options have the same meaning as the B<RSA> algorithm.
148 =item B<rsa_pss_keygen_md:digest>
150 If set the key is restricted and can only use B<digest> for signing.
152 =item B<rsa_pss_keygen_mgf1_md:digest>
154 If set the key is restricted and can only use B<digest> as it's MGF1
157 =item B<rsa_pss_keygen_saltlen:len>
159 If set the key is restricted and B<len> specifies the minimum salt length.
163 =head1 DSA PARAMETER GENERATION OPTIONS
167 =item B<dsa_paramgen_bits:numbits>
169 The number of bits in the generated parameters. If not specified 1024 is used.
173 =head1 DH PARAMETER GENERATION OPTIONS
177 =item B<dh_paramgen_prime_len:numbits>
179 The number of bits in the prime parameter B<p>.
181 =item B<dh_paramgen_generator:value>
183 The value to use for the generator B<g>.
185 =item B<dh_rfc5114:num>
187 If this option is set then the appropriate RFC5114 parameters are used
188 instead of generating new parameters. The value B<num> can take the
189 values 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of
190 1024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup
191 and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections
192 2.1, 2.2 and 2.3 respectively.
196 =head1 EC PARAMETER GENERATION OPTIONS
198 The EC parameter generation options below can also
199 be supplied as EC key generation options. This can (for example) generate a
200 key from a named curve without the need to use an explicit parameter file.
204 =item B<ec_paramgen_curve:curve>
206 The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
208 =item B<ec_param_enc:encoding>
210 The encoding to use for parameters. The "encoding" parameter must be either
211 "named_curve" or "explicit".
215 =head1 GOST2001 KEY GENERATION AND PARAMETER OPTIONS
217 Gost 2001 support is not enabled by default. To enable this algorithm,
218 one should load the ccgost engine in the OpenSSL configuration file.
219 See README.gost file in the engines/ccgost directory of the source
220 distribution for more details.
222 Use of a parameter file for the GOST R 34.10 algorithm is optional.
223 Parameters can be specified during key generation directly as well as
224 during generation of parameter file.
228 =item B<paramset:name>
230 Specifies GOST R 34.10-2001 parameter set according to RFC 4357.
231 Parameter set can be specified using abbreviated name, object short name or
232 numeric OID. Following parameter sets are supported:
235 A 1.2.643.2.2.35.1 Signature
236 B 1.2.643.2.2.35.2 Signature
237 C 1.2.643.2.2.35.3 Signature
238 XA 1.2.643.2.2.36.0 Key exchange
239 XB 1.2.643.2.2.36.1 Key exchange
240 test 1.2.643.2.2.35.0 Test purposes
244 =head1 X25519 KEY GENERATION OPTIONS
246 The X25519 algorithm does not currently support any key generation options.
251 The use of the genpkey program is encouraged over the algorithm specific
252 utilities because additional algorithm options and ENGINE provided algorithms
257 Generate an RSA private key using default parameters:
259 openssl genpkey -algorithm RSA -out key.pem
261 Encrypt output private key using 128 bit AES and the passphrase "hello":
263 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
265 Generate a 2048 bit RSA key using 3 as the public exponent:
267 openssl genpkey -algorithm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048 \
268 -pkeyopt rsa_keygen_pubexp:3
270 Generate 1024 bit DSA parameters:
272 openssl genpkey -genparam -algorithm DSA -out dsap.pem \
273 -pkeyopt dsa_paramgen_bits:1024
275 Generate DSA key from parameters:
277 openssl genpkey -paramfile dsap.pem -out dsakey.pem
279 Generate 1024 bit DH parameters:
281 openssl genpkey -genparam -algorithm DH -out dhp.pem \
282 -pkeyopt dh_paramgen_prime_len:1024
284 Output RFC5114 2048 bit DH parameters with 224 bit subgroup:
286 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt dh_rfc5114:2
288 Generate DH key from parameters:
290 openssl genpkey -paramfile dhp.pem -out dhkey.pem
292 Generate EC parameters:
294 openssl genpkey -genparam -algorithm EC -out ecp.pem \
295 -pkeyopt ec_paramgen_curve:secp384r1 \
296 -pkeyopt ec_param_enc:named_curve
298 Generate EC key from parameters:
300 openssl genpkey -paramfile ecp.pem -out eckey.pem
302 Generate EC key directly:
304 openssl genpkey -algorithm EC -out eckey.pem \
305 -pkeyopt ec_paramgen_curve:P-384 \
306 -pkeyopt ec_param_enc:named_curve
308 Generate an X25519 private key:
310 openssl genpkey -algorithm X25519 -out xkey.pem
314 The ability to use NIST curve names, and to generate an EC key directly,
315 were added in OpenSSL 1.0.2.
319 Copyright 2006-2017 The OpenSSL Project Authors. All Rights Reserved.
321 Licensed under the OpenSSL license (the "License"). You may not use
322 this file except in compliance with the License. You can obtain a copy
323 in the file LICENSE in the source distribution or at
324 L<https://www.openssl.org/source/license.html>.