4 {- join("\n", @autowarntext) -}
10 openssl-genpkey - generate a private key
17 [B<-outform> B<DER>|B<PEM>]
20 [B<-paramfile> I<file>]
21 [B<-algorithm> I<alg>]
22 [B<-pkeyopt> I<opt>:I<value>]
25 {- $OpenSSL::safe::opt_engine_synopsis -}
26 {- $OpenSSL::safe::opt_provider_synopsis -}
28 =for openssl ifdef engine
32 This command generates a private key.
40 Print out a usage message.
42 =item B<-out> I<filename>
44 Output the key to the specified file. If this argument is not specified then
45 standard output is used.
47 =item B<-outform> B<DER>|B<PEM>
49 The output format; the default is B<PEM>.
50 See L<openssl(1)/Format Options> for details.
54 The output file password source. For more information about the format of I<arg>
55 see L<openssl(1)/Pass Phrase Options>.
59 This option encrypts the private key with the supplied cipher. Any algorithm
60 name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>.
62 =item B<-algorithm> I<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. Engines may add algorithms in addition to the standard
69 Valid built-in algorithm names for private key generation are RSA, RSA-PSS, EC,
70 X25519, X448, ED25519 and ED448.
72 Valid built-in algorithm names for parameter generation (see the B<-genparam>
73 option) are DH, DSA and EC.
75 Note that the algorithm name X9.42 DH may be used as a synonym for the DH
76 algorithm. These are identical and do not indicate the type of parameters that
77 will be generated. Use the B<dh_paramgen_type> option to indicate whether PKCS#3
78 or X9.42 DH parameters are required. See L</DH Parameter Generation Options>
79 below for more details.
81 =item B<-pkeyopt> I<opt>:I<value>
83 Set the public key algorithm option I<opt> to I<value>. The precise set of
84 options supported depends on the public key algorithm used and its
85 implementation. See L</KEY GENERATION OPTIONS> and
86 L</PARAMETER GENERATION OPTIONS> below for more details.
90 Generate a set of parameters instead of a private key. If used this option must
91 precede any B<-algorithm>, B<-paramfile> or B<-pkeyopt> options.
93 =item B<-paramfile> I<filename>
95 Some public key algorithms generate a private key based on a set of parameters.
96 They can be supplied using this option. If this option is used the public key
97 algorithm used is determined by the parameters. If used this option must
98 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
99 are mutually exclusive.
103 Print an (unencrypted) text representation of private and public keys and
104 parameters along with the PEM or DER structure.
106 {- $OpenSSL::safe::opt_engine_item -}
108 {- $OpenSSL::safe::opt_provider_item -}
112 =head1 KEY GENERATION OPTIONS
114 The options supported by each algorithm and indeed each implementation of an
115 algorithm can vary. The options for the OpenSSL implementations are detailed
116 below. There are no key generation options defined for the X25519, X448, ED25519
119 =head2 RSA Key Generation Options
123 =item B<rsa_keygen_bits:numbits>
125 The number of bits in the generated key. If not specified 2048 is used.
127 =item B<rsa_keygen_primes:numprimes>
129 The number of primes in the generated key. If not specified 2 is used.
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 C<0x>. Default value is 65537.
138 =head2 RSA-PSS Key Generation Options
140 Note: by default an B<RSA-PSS> key has no parameter restrictions.
144 =item B<rsa_keygen_bits>:I<numbits>, B<rsa_keygen_primes>:I<numprimes>,
145 B<rsa_keygen_pubexp>:I<value>
147 These options have the same meaning as the B<RSA> algorithm.
149 =item B<rsa_pss_keygen_md>:I<digest>
151 If set the key is restricted and can only use I<digest> for signing.
153 =item B<rsa_pss_keygen_mgf1_md>:I<digest>
155 If set the key is restricted and can only use I<digest> as it's MGF1
158 =item B<rsa_pss_keygen_saltlen>:I<len>
160 If set the key is restricted and I<len> specifies the minimum salt length.
164 =head2 EC Key Generation Options
166 The EC key generation options can also be used for parameter generation.
170 =item B<ec_paramgen_curve>:I<curve>
172 The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
174 =item B<ec_param_enc>:I<encoding>
176 The encoding to use for parameters. The I<encoding> parameter must be either
177 B<named_curve> or B<explicit>. The default value is B<named_curve>.
181 =head1 PARAMETER GENERATION OPTIONS
183 The options supported by each algorithm and indeed each implementation of an
184 algorithm can vary. The options for the OpenSSL implementations are detailed
187 =head2 DSA Parameter Generation Options
191 =item B<dsa_paramgen_bits>:I<numbits>
193 The number of bits in the generated prime. If not specified 2048 is used.
195 =item B<dsa_paramgen_q_bits>:I<numbits>
197 The number of bits in the q parameter. Must be one of 160, 224 or 256. If not
198 specified 224 is used.
200 =item B<dsa_paramgen_md>:I<digest>
202 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
203 or B<sha256>. If set, then the number of bits in B<q> will match the output size
204 of the specified digest and the B<dsa_paramgen_q_bits> parameter will be
205 ignored. If not set, then a digest will be used that gives an output matching
206 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it 224
207 or B<sha256> if it is 256.
211 =head2 DH Parameter Generation Options
215 =item B<dh_paramgen_prime_len>:I<numbits>
217 The number of bits in the prime parameter I<p>. The default is 2048.
219 =item B<dh_paramgen_subprime_len>:I<numbits>
221 The number of bits in the sub prime parameter I<q>. The default is 256 if the
222 prime is at least 2048 bits long or 160 otherwise. Only relevant if used in
223 conjunction with the B<dh_paramgen_type> option to generate X9.42 DH parameters.
225 =item B<dh_paramgen_generator>:I<value>
227 The value to use for the generator I<g>. The default is 2.
229 =item B<dh_paramgen_type>:I<value>
231 The type of DH parameters to generate. Use 0 for PKCS#3 DH and 1 for X9.42 DH.
234 =item B<dh_rfc5114>:I<num>
236 If this option is set, then the appropriate RFC5114 parameters are used
237 instead of generating new parameters. The value I<num> can be one of
238 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of
239 1024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup
240 and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections
241 2.1, 2.2 and 2.3 respectively. If present this overrides all other DH parameter
246 =head2 EC Parameter Generation Options
248 The EC parameter generation options are the same as for key generation. See
249 L</EC Key Generation Options> above.
253 The use of the genpkey program is encouraged over the algorithm specific
254 utilities because additional algorithm options and ENGINE provided algorithms
259 Generate an RSA private key using default parameters:
261 openssl genpkey -algorithm RSA -out key.pem
263 Encrypt output private key using 128 bit AES and the passphrase "hello":
265 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
267 Generate a 2048 bit RSA key using 3 as the public exponent:
269 openssl genpkey -algorithm RSA -out key.pem \
270 -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3
272 Generate 2048 bit DSA parameters:
274 openssl genpkey -genparam -algorithm DSA -out dsap.pem \
275 -pkeyopt dsa_paramgen_bits:2048
277 Generate DSA key from parameters:
279 openssl genpkey -paramfile dsap.pem -out dsakey.pem
281 Generate 2048 bit DH parameters:
283 openssl genpkey -genparam -algorithm DH -out dhp.pem \
284 -pkeyopt dh_paramgen_prime_len:2048
286 Generate 2048 bit X9.42 DH parameters:
288 openssl genpkey -genparam -algorithm DH -out dhpx.pem \
289 -pkeyopt dh_paramgen_prime_len:2048 \
290 -pkeyopt dh_paramgen_type:1
292 Output RFC5114 2048 bit DH parameters with 224 bit subgroup:
294 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt dh_rfc5114:2
296 Generate DH key from parameters:
298 openssl genpkey -paramfile dhp.pem -out dhkey.pem
300 Generate EC parameters:
302 openssl genpkey -genparam -algorithm EC -out ecp.pem \
303 -pkeyopt ec_paramgen_curve:secp384r1 \
304 -pkeyopt ec_param_enc:named_curve
306 Generate EC key from parameters:
308 openssl genpkey -paramfile ecp.pem -out eckey.pem
310 Generate EC key directly:
312 openssl genpkey -algorithm EC -out eckey.pem \
313 -pkeyopt ec_paramgen_curve:P-384 \
314 -pkeyopt ec_param_enc:named_curve
316 Generate an X25519 private key:
318 openssl genpkey -algorithm X25519 -out xkey.pem
320 Generate an ED448 private key:
322 openssl genpkey -algorithm ED448 -out xkey.pem
326 The ability to use NIST curve names, and to generate an EC key directly,
327 were added in OpenSSL 1.0.2.
328 The ability to generate X25519 keys was added in OpenSSL 1.1.0.
329 The ability to generate X448, ED25519 and ED448 keys was added in OpenSSL 1.1.1.
333 Copyright 2006-2019 The OpenSSL Project Authors. All Rights Reserved.
335 Licensed under the Apache License 2.0 (the "License"). You may not use
336 this file except in compliance with the License. You can obtain a copy
337 in the file LICENSE in the source distribution or at
338 L<https://www.openssl.org/source/license.html>.