4 {- join("\n", @autowarntext) -}
10 openssl-genpkey - generate a private key
17 [B<-outform> B<DER>|B<PEM>]
22 [B<-paramfile> I<file>]
23 [B<-algorithm> I<alg>]
24 [B<-pkeyopt> I<opt>:I<value>]
27 {- $OpenSSL::safe::opt_engine_synopsis -}{- $OpenSSL::safe::opt_provider_synopsis -}
28 {- $OpenSSL::safe::opt_config_synopsis -}
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, except when B<-genparam> is given; the default is B<PEM>.
50 See L<openssl-format-options(1)> for details.
52 When B<-genparam> is given, B<-outform> is ignored.
56 Output "status dots" while generating keys.
60 Do not output "status dots" while generating keys.
64 The output file password source. For more information about the format of I<arg>
65 see L<openssl-passphrase-options(1)>.
69 This option encrypts the private key with the supplied cipher. Any algorithm
70 name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>.
72 =item B<-algorithm> I<alg>
74 Public key algorithm to use such as RSA, DSA, DH or DHX. If used this option must
75 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
76 are mutually exclusive. Engines may add algorithms in addition to the standard
79 Valid built-in algorithm names for private key generation are RSA, RSA-PSS, EC,
80 X25519, X448, ED25519 and ED448.
82 Valid built-in algorithm names for parameter generation (see the B<-genparam>
83 option) are DH, DSA and EC.
85 Note that the algorithm name X9.42 DH may be used as a synonym for DHX keys and
86 PKCS#3 refers to DH Keys. Some options are not shared between DH and DHX keys.
88 =item B<-pkeyopt> I<opt>:I<value>
90 Set the public key algorithm option I<opt> to I<value>. The precise set of
91 options supported depends on the public key algorithm used and its
92 implementation. See L</KEY GENERATION OPTIONS> and
93 L</PARAMETER GENERATION OPTIONS> below for more details.
97 Generate a set of parameters instead of a private key. If used this option must
98 precede any B<-algorithm>, B<-paramfile> or B<-pkeyopt> options.
100 =item B<-paramfile> I<filename>
102 Some public key algorithms generate a private key based on a set of parameters.
103 They can be supplied using this option. If this option is used the public key
104 algorithm used is determined by the parameters. If used this option must
105 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
106 are mutually exclusive.
110 Print an (unencrypted) text representation of private and public keys and
111 parameters along with the PEM or DER structure.
113 {- $OpenSSL::safe::opt_engine_item -}
115 {- $OpenSSL::safe::opt_provider_item -}
117 {- $OpenSSL::safe::opt_config_item -}
121 =head1 KEY GENERATION OPTIONS
123 The options supported by each algorithm and indeed each implementation of an
124 algorithm can vary. The options for the OpenSSL implementations are detailed
125 below. There are no key generation options defined for the X25519, X448, ED25519
128 =head2 RSA Key Generation Options
132 =item B<rsa_keygen_bits:numbits>
134 The number of bits in the generated key. If not specified 2048 is used.
136 =item B<rsa_keygen_primes:numprimes>
138 The number of primes in the generated key. If not specified 2 is used.
140 =item B<rsa_keygen_pubexp:value>
142 The RSA public exponent value. This can be a large decimal or
143 hexadecimal value if preceded by C<0x>. Default value is 65537.
147 =head2 RSA-PSS Key Generation Options
149 Note: by default an B<RSA-PSS> key has no parameter restrictions.
153 =item B<rsa_keygen_bits>:I<numbits>, B<rsa_keygen_primes>:I<numprimes>,
154 B<rsa_keygen_pubexp>:I<value>
156 These options have the same meaning as the B<RSA> algorithm.
158 =item B<rsa_pss_keygen_md>:I<digest>
160 If set the key is restricted and can only use I<digest> for signing.
162 =item B<rsa_pss_keygen_mgf1_md>:I<digest>
164 If set the key is restricted and can only use I<digest> as it's MGF1
167 =item B<rsa_pss_keygen_saltlen>:I<len>
169 If set the key is restricted and I<len> specifies the minimum salt length.
173 =head2 EC Key Generation Options
175 The EC key generation options can also be used for parameter generation.
179 =item B<ec_paramgen_curve>:I<curve>
181 The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
183 =item B<ec_param_enc>:I<encoding>
185 The encoding to use for parameters. The I<encoding> parameter must be either
186 B<named_curve> or B<explicit>. The default value is B<named_curve>.
190 =head2 DH Key Generation Options
194 =item B<group>:I<name>
196 The B<paramfile> option is not required if a named group is used here.
197 See the L</DH Parameter Generation Options> section below.
202 =head1 PARAMETER GENERATION OPTIONS
204 The options supported by each algorithm and indeed each implementation of an
205 algorithm can vary. The options for the OpenSSL implementations are detailed
208 =head2 DSA Parameter Generation Options
212 =item B<dsa_paramgen_bits>:I<numbits>
214 The number of bits in the generated prime. If not specified 2048 is used.
216 =item B<dsa_paramgen_q_bits>:I<numbits>
218 =item B<qbits>:I<numbits>
220 The number of bits in the q parameter. Must be one of 160, 224 or 256. If not
221 specified 224 is used.
223 =item B<dsa_paramgen_md>:I<digest>
225 =item B<digest>:I<digest>
227 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
228 or B<sha256>. If set, then the number of bits in B<q> will match the output size
229 of the specified digest and the B<dsa_paramgen_q_bits> parameter will be
230 ignored. If not set, then a digest will be used that gives an output matching
231 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it 224
232 or B<sha256> if it is 256.
234 =item B<properties>:I<query>
236 The I<digest> property I<query> string to use when fetching a digest from a provider.
238 =item B<type>:I<type>
240 The type of generation to use. Set this to 1 to use legacy FIPS186-2 parameter
241 generation. The default of 0 uses FIPS186-4 parameter generation.
243 =item B<gindex>:I<index>
245 The index to use for canonical generation and verification of the generator g.
246 Set this to a positive value ranging from 0..255 to use this mode. Larger values
247 will only use the bottom byte.
248 This I<index> must then be reused during key validation to verify the value of g.
249 If this value is not set then g is not verifiable. The default value is -1.
251 =item B<hexseed>:I<seed>
253 The seed I<seed> data to use instead of generating a random seed internally.
254 This should be used for testing purposes only. This will either produced fixed
255 values for the generated parameters OR it will fail if the seed did not
256 generate valid primes.
260 =head2 DH Parameter Generation Options
262 For most use cases it is recommended to use the B<group> option rather than
263 the B<type> options. Note that the B<group> option is not used by default if
264 no parameter generation options are specified.
268 =item B<group>:I<name>
270 =item B<dh_param>:I<name>
272 Use a named DH group to select constant values for the DH parameters.
273 All other options will be ignored if this value is set.
275 Valid values that are associated with the B<algorithm> of B<"DH"> are:
276 "ffdhe2048", "ffdhe3072", "ffdhe4096", "ffdhe6144", "ffdhe8192",
277 "modp_1536", "modp_2048", "modp_3072", "modp_4096", "modp_6144", "modp_8192".
279 Valid values that are associated with the B<algorithm> of B<"DHX"> are the
280 RFC5114 names "dh_1024_160", "dh_2048_224", "dh_2048_256".
282 =item B<dh_rfc5114>:I<num>
284 If this option is set, then the appropriate RFC5114 parameters are used
285 instead of generating new parameters. The value I<num> can be one of
286 1, 2 or 3 that are equivalent to using the option B<group> with one of
287 "dh_1024_160", "dh_2048_224" or "dh_2048_256".
288 All other options will be ignored if this value is set.
290 =item B<pbits>:I<numbits>
292 =item B<dh_paramgen_prime_len>:I<numbits>
294 The number of bits in the prime parameter I<p>. The default is 2048.
296 =item B<qbits>:I<numbits>
298 =item B<dh_paramgen_subprime_len>:I<numbits>
300 The number of bits in the sub prime parameter I<q>. The default is 224.
301 Only relevant if used in conjunction with the B<dh_paramgen_type> option to
302 generate DHX parameters.
304 =item B<safeprime-generator>:I<value>
306 =item B<dh_paramgen_generator>:I<value>
308 The value to use for the generator I<g>. The default is 2.
309 The B<algorithm> option must be B<"DH"> for this parameter to be used.
311 =item B<type>:I<string>
313 The type name of DH parameters to generate. Valid values are:
319 Use a safe prime generator with the option B<safeprime_generator>
320 The B<algorithm> option must be B<"DH">.
324 FIPS186-4 parameter generation.
325 The B<algorithm> option must be B<"DHX">.
329 FIPS186-4 parameter generation.
330 The B<algorithm> option must be B<"DHX">.
334 Can be used with the option B<pbits> to select one of
335 "ffdhe2048", "ffdhe3072", "ffdhe4096", "ffdhe6144" or "ffdhe8192".
336 The B<algorithm> option must be B<"DH">.
340 Selects a default type based on the B<algorithm>. This is used by the
341 OpenSSL default provider to set the type for backwards compatibility.
342 If B<algorithm> is B<"DH"> then B<"generator"> is used.
343 If B<algorithm> is B<"DHX"> then B<"fips186_2"> is used.
347 =item B<dh_paramgen_type>:I<value>
349 The type of DH parameters to generate. Valid values are 0, 1, 2 or 3
350 which correspond to setting the option B<type> to
351 "generator", "fips186_2", "fips186_4" or "group".
353 =item B<digest>:I<digest>
355 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
356 or B<sha256>. If set, then the number of bits in B<qbits> will match the output
357 size of the specified digest and the B<qbits> parameter will be
358 ignored. If not set, then a digest will be used that gives an output matching
359 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it is
360 224 or B<sha256> if it is 256.
361 This is only used by "fips186_4" and "fips186_2" key generation.
363 =item B<properties>:I<query>
365 The I<digest> property I<query> string to use when fetching a digest from a provider.
366 This is only used by "fips186_4" and "fips186_2" key generation.
368 =item B<gindex>:I<index>
370 The index to use for canonical generation and verification of the generator g.
371 Set this to a positive value ranging from 0..255 to use this mode. Larger values
372 will only use the bottom byte.
373 This I<index> must then be reused during key validation to verify the value of g.
374 If this value is not set then g is not verifiable. The default value is -1.
375 This is only used by "fips186_4" and "fips186_2" key generation.
377 =item B<hexseed>:I<seed>
379 The seed I<seed> data to use instead of generating a random seed internally.
380 This should be used for testing purposes only. This will either produced fixed
381 values for the generated parameters OR it will fail if the seed did not
382 generate valid primes.
383 This is only used by "fips186_4" and "fips186_2" key generation.
387 =head2 EC Parameter Generation Options
389 The EC parameter generation options are the same as for key generation. See
390 L</EC Key Generation Options> above.
394 The use of the genpkey program is encouraged over the algorithm specific
395 utilities because additional algorithm options and ENGINE provided algorithms
400 Generate an RSA private key using default parameters:
402 openssl genpkey -algorithm RSA -out key.pem
404 Encrypt output private key using 128 bit AES and the passphrase "hello":
406 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
408 Generate a 2048 bit RSA key using 3 as the public exponent:
410 openssl genpkey -algorithm RSA -out key.pem \
411 -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3
413 Generate 2048 bit DSA parameters that can be validated: The output values for
414 gindex and seed are required for key validation purposes and are not saved to
415 the output pem file).
417 openssl genpkey -genparam -algorithm DSA -out dsap.pem -pkeyopt pbits:2048 \
418 -pkeyopt qbits:224 -pkeyopt digest:SHA256 -pkeyopt gindex:1 -text
420 Generate DSA key from parameters:
422 openssl genpkey -paramfile dsap.pem -out dsakey.pem
424 Generate 4096 bit DH Key using safe prime group ffdhe4096:
426 openssl genpkey -algorithm DH -out dhkey.pem -pkeyopt group:ffdhe4096
428 Generate 2048 bit X9.42 DH key with 256 bit subgroup using RFC5114 group3:
430 openssl genpkey -algorithm DHX -out dhkey.pem -pkeyopt dh_rfc5114:3
432 Generate a DH key using a DH parameters file:
434 openssl genpkey -paramfile dhp.pem -out dhkey.pem
436 Output DH parameters for safe prime group ffdhe2048:
438 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt group:ffdhe2048
440 Output 2048 bit X9.42 DH parameters with 224 bit subgroup using RFC5114 group2:
442 openssl genpkey -genparam -algorithm DHX -out dhp.pem -pkeyopt dh_rfc5114:2
444 Output 2048 bit X9.42 DH parameters with 224 bit subgroup using FIP186-4 keygen:
446 openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
447 -pkeyopt pbits:2048 -pkeyopt qbits:224 -pkeyopt digest:SHA256 \
448 -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:2
450 Output 1024 bit X9.42 DH parameters with 160 bit subgroup using FIP186-2 keygen:
452 openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
453 -pkeyopt pbits:1024 -pkeyopt qbits:160 -pkeyopt digest:SHA1 \
454 -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:1
456 Output 2048 bit DH parameters:
458 openssl genpkey -genparam -algorithm DH -out dhp.pem \
459 -pkeyopt dh_paramgen_prime_len:2048
461 Output 2048 bit DH parameters using a generator:
463 openssl genpkey -genparam -algorithm DH -out dhpx.pem \
464 -pkeyopt dh_paramgen_prime_len:2048 \
465 -pkeyopt dh_paramgen_type:1
467 Generate EC parameters:
469 openssl genpkey -genparam -algorithm EC -out ecp.pem \
470 -pkeyopt ec_paramgen_curve:secp384r1 \
471 -pkeyopt ec_param_enc:named_curve
473 Generate EC key from parameters:
475 openssl genpkey -paramfile ecp.pem -out eckey.pem
477 Generate EC key directly:
479 openssl genpkey -algorithm EC -out eckey.pem \
480 -pkeyopt ec_paramgen_curve:P-384 \
481 -pkeyopt ec_param_enc:named_curve
483 Generate an X25519 private key:
485 openssl genpkey -algorithm X25519 -out xkey.pem
487 Generate an ED448 private key:
489 openssl genpkey -algorithm ED448 -out xkey.pem
493 The ability to use NIST curve names, and to generate an EC key directly,
494 were added in OpenSSL 1.0.2.
495 The ability to generate X25519 keys was added in OpenSSL 1.1.0.
496 The ability to generate X448, ED25519 and ED448 keys was added in OpenSSL 1.1.1.
498 The B<-engine> option was deprecated in OpenSSL 3.0.
502 Copyright 2006-2022 The OpenSSL Project Authors. All Rights Reserved.
504 Licensed under the Apache License 2.0 (the "License"). You may not use
505 this file except in compliance with the License. You can obtain a copy
506 in the file LICENSE in the source distribution or at
507 L<https://www.openssl.org/source/license.html>.