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 -}
27 {- $OpenSSL::safe::opt_config_synopsis -}
29 =for openssl ifdef engine
33 This command generates a private key.
41 Print out a usage message.
43 =item B<-out> I<filename>
45 Output the key to the specified file. If this argument is not specified then
46 standard output is used.
48 =item B<-outform> B<DER>|B<PEM>
50 The output format; the default is B<PEM>.
51 See L<openssl(1)/Format Options> for details.
55 The output file password source. For more information about the format of I<arg>
56 see L<openssl(1)/Pass Phrase Options>.
60 This option encrypts the private key with the supplied cipher. Any algorithm
61 name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>.
63 =item B<-algorithm> I<alg>
65 Public key algorithm to use such as RSA, DSA or DH. If used this option must
66 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
67 are mutually exclusive. Engines may add algorithms in addition to the standard
70 Valid built-in algorithm names for private key generation are RSA, RSA-PSS, EC,
71 X25519, X448, ED25519 and ED448.
73 Valid built-in algorithm names for parameter generation (see the B<-genparam>
74 option) are DH, DSA and EC.
76 Note that the algorithm name X9.42 DH may be used as a synonym for the DH
77 algorithm. These are identical and do not indicate the type of parameters that
78 will be generated. Use the B<dh_paramgen_type> option to indicate whether PKCS#3
79 or X9.42 DH parameters are required. See L</DH Parameter Generation Options>
80 below for more details.
82 =item B<-pkeyopt> I<opt>:I<value>
84 Set the public key algorithm option I<opt> to I<value>. The precise set of
85 options supported depends on the public key algorithm used and its
86 implementation. See L</KEY GENERATION OPTIONS> and
87 L</PARAMETER GENERATION OPTIONS> below for more details.
91 Generate a set of parameters instead of a private key. If used this option must
92 precede any B<-algorithm>, B<-paramfile> or B<-pkeyopt> options.
94 =item B<-paramfile> I<filename>
96 Some public key algorithms generate a private key based on a set of parameters.
97 They can be supplied using this option. If this option is used the public key
98 algorithm used is determined by the parameters. If used this option must
99 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
100 are mutually exclusive.
104 Print an (unencrypted) text representation of private and public keys and
105 parameters along with the PEM or DER structure.
107 {- $OpenSSL::safe::opt_engine_item -}
109 {- $OpenSSL::safe::opt_provider_item -}
111 {- $OpenSSL::safe::opt_config_item -}
115 =head1 KEY GENERATION OPTIONS
117 The options supported by each algorithm and indeed each implementation of an
118 algorithm can vary. The options for the OpenSSL implementations are detailed
119 below. There are no key generation options defined for the X25519, X448, ED25519
122 =head2 RSA Key Generation Options
126 =item B<rsa_keygen_bits:numbits>
128 The number of bits in the generated key. If not specified 2048 is used.
130 =item B<rsa_keygen_primes:numprimes>
132 The number of primes in the generated key. If not specified 2 is used.
134 =item B<rsa_keygen_pubexp:value>
136 The RSA public exponent value. This can be a large decimal or
137 hexadecimal value if preceded by C<0x>. Default value is 65537.
141 =head2 RSA-PSS Key Generation Options
143 Note: by default an B<RSA-PSS> key has no parameter restrictions.
147 =item B<rsa_keygen_bits>:I<numbits>, B<rsa_keygen_primes>:I<numprimes>,
148 B<rsa_keygen_pubexp>:I<value>
150 These options have the same meaning as the B<RSA> algorithm.
152 =item B<rsa_pss_keygen_md>:I<digest>
154 If set the key is restricted and can only use I<digest> for signing.
156 =item B<rsa_pss_keygen_mgf1_md>:I<digest>
158 If set the key is restricted and can only use I<digest> as it's MGF1
161 =item B<rsa_pss_keygen_saltlen>:I<len>
163 If set the key is restricted and I<len> specifies the minimum salt length.
167 =head2 EC Key Generation Options
169 The EC key generation options can also be used for parameter generation.
173 =item B<ec_paramgen_curve>:I<curve>
175 The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
177 =item B<ec_param_enc>:I<encoding>
179 The encoding to use for parameters. The I<encoding> parameter must be either
180 B<named_curve> or B<explicit>. The default value is B<named_curve>.
184 =head1 PARAMETER GENERATION OPTIONS
186 The options supported by each algorithm and indeed each implementation of an
187 algorithm can vary. The options for the OpenSSL implementations are detailed
190 =head2 DSA Parameter Generation Options
194 =item B<dsa_paramgen_bits>:I<numbits>
196 The number of bits in the generated prime. If not specified 2048 is used.
198 =item B<dsa_paramgen_q_bits>:I<numbits>
200 =item B<qbits>:I<numbits>
202 The number of bits in the q parameter. Must be one of 160, 224 or 256. If not
203 specified 224 is used.
205 =item B<dsa_paramgen_md>:I<digest>
207 =item B<digest>:I<digest>
209 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
210 or B<sha256>. If set, then the number of bits in B<q> will match the output size
211 of the specified digest and the B<dsa_paramgen_q_bits> parameter will be
212 ignored. If not set, then a digest will be used that gives an output matching
213 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it 224
214 or B<sha256> if it is 256.
217 =item B<properties>:I<query>
219 The I<digest> property I<query> string to use when fetching a digest from a provider.
221 =item B<type>:I<type>
223 The type of generation to use. Set this to 1 to use legacy FIPS186-2 parameter
224 generation. The default of 0 uses FIPS186-4 parameter generation.
226 =item B<gindex>:I<index>
228 The index to use for canonical generation and verification of the generator g.
229 Set this to a positive value ranging from 0..255 to use this mode. Larger values
230 will only use the bottom byte.
231 This I<index> must then be reused during key validation to verify the value of g.
232 If this value is not set then g is not verifiable. The default value is -1.
234 =item B<hexseed>:I<seed>
236 The seed I<seed> data to use instead of generating a random seed internally.
237 This should be used for testing purposes only. This will either produced fixed
238 values for the generated parameters OR it will fail if the seed did not
239 generate valid primes.
243 =head2 DH Parameter Generation Options
247 =item B<dh_paramgen_prime_len>:I<numbits>
249 The number of bits in the prime parameter I<p>. The default is 2048.
251 =item B<dh_paramgen_subprime_len>:I<numbits>
253 The number of bits in the sub prime parameter I<q>. The default is 256 if the
254 prime is at least 2048 bits long or 160 otherwise. Only relevant if used in
255 conjunction with the B<dh_paramgen_type> option to generate X9.42 DH parameters.
257 =item B<dh_paramgen_generator>:I<value>
259 The value to use for the generator I<g>. The default is 2.
261 =item B<dh_paramgen_type>:I<value>
263 The type of DH parameters to generate. Use 0 for PKCS#3 DH and 1 for X9.42 DH.
266 =item B<dh_rfc5114>:I<num>
268 If this option is set, then the appropriate RFC5114 parameters are used
269 instead of generating new parameters. The value I<num> can be one of
270 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of
271 1024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup
272 and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections
273 2.1, 2.2 and 2.3 respectively. If present this overrides all other DH parameter
278 =head2 EC Parameter Generation Options
280 The EC parameter generation options are the same as for key generation. See
281 L</EC Key Generation Options> above.
285 The use of the genpkey program is encouraged over the algorithm specific
286 utilities because additional algorithm options and ENGINE provided algorithms
291 Generate an RSA private key using default parameters:
293 openssl genpkey -algorithm RSA -out key.pem
295 Encrypt output private key using 128 bit AES and the passphrase "hello":
297 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
299 Generate a 2048 bit RSA key using 3 as the public exponent:
301 openssl genpkey -algorithm RSA -out key.pem \
302 -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3
304 Generate 2048 bit DSA parameters that can be validated: The output values for
305 gindex and seed are required for key validation purposes and are not saved to
306 the output pem file).
308 openssl genpkey -genparam -algorithm DSA -out dsap.pem -pkeyopt pbits:2048 \
309 -pkeyopt qbits:224 -pkeyopt digest:SHA256 -pkeyopt gindex:1 -text
311 Generate DSA key from parameters:
313 openssl genpkey -paramfile dsap.pem -out dsakey.pem
315 Generate 2048 bit DH parameters:
317 openssl genpkey -genparam -algorithm DH -out dhp.pem \
318 -pkeyopt dh_paramgen_prime_len:2048
320 Generate 2048 bit X9.42 DH parameters:
322 openssl genpkey -genparam -algorithm DH -out dhpx.pem \
323 -pkeyopt dh_paramgen_prime_len:2048 \
324 -pkeyopt dh_paramgen_type:1
326 Output RFC5114 2048 bit DH parameters with 224 bit subgroup:
328 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt dh_rfc5114:2
330 Generate DH key from parameters:
332 openssl genpkey -paramfile dhp.pem -out dhkey.pem
334 Generate EC parameters:
336 openssl genpkey -genparam -algorithm EC -out ecp.pem \
337 -pkeyopt ec_paramgen_curve:secp384r1 \
338 -pkeyopt ec_param_enc:named_curve
340 Generate EC key from parameters:
342 openssl genpkey -paramfile ecp.pem -out eckey.pem
344 Generate EC key directly:
346 openssl genpkey -algorithm EC -out eckey.pem \
347 -pkeyopt ec_paramgen_curve:P-384 \
348 -pkeyopt ec_param_enc:named_curve
350 Generate an X25519 private key:
352 openssl genpkey -algorithm X25519 -out xkey.pem
354 Generate an ED448 private key:
356 openssl genpkey -algorithm ED448 -out xkey.pem
360 The ability to use NIST curve names, and to generate an EC key directly,
361 were added in OpenSSL 1.0.2.
362 The ability to generate X25519 keys was added in OpenSSL 1.1.0.
363 The ability to generate X448, ED25519 and ED448 keys was added in OpenSSL 1.1.1.
365 The B<-engine> option was deprecated in OpenSSL 3.0.
369 Copyright 2006-2020 The OpenSSL Project Authors. All Rights Reserved.
371 Licensed under the Apache License 2.0 (the "License"). You may not use
372 this file except in compliance with the License. You can obtain a copy
373 in the file LICENSE in the source distribution or at
374 L<https://www.openssl.org/source/license.html>.