4 {- join("\n", @autowarntext) -}
10 openssl-genpkey - generate a private key
17 [B<-outform> B<DER>|B<PEM>]
21 [B<-paramfile> I<file>]
22 [B<-algorithm> I<alg>]
23 [B<-pkeyopt> I<opt>:I<value>]
26 {- $OpenSSL::safe::opt_engine_synopsis -}{- $OpenSSL::safe::opt_provider_synopsis -}
27 {- $OpenSSL::safe::opt_config_synopsis -}
31 This command generates a private key.
39 Print out a usage message.
41 =item B<-out> I<filename>
43 Output the key to the specified file. If this argument is not specified then
44 standard output is used.
46 =item B<-outform> B<DER>|B<PEM>
48 The output format, except when B<-genparam> is given; the default is B<PEM>.
49 See L<openssl-format-options(1)> for details.
51 When B<-genparam> is given, B<-outform> is ignored.
55 Do not output "status dots" while generating keys.
59 The output file password source. For more information about the format of I<arg>
60 see L<openssl-passphrase-options(1)>.
64 This option encrypts the private key with the supplied cipher. Any algorithm
65 name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>.
67 =item B<-algorithm> I<alg>
69 Public key algorithm to use such as RSA, DSA, DH or DHX. If used this option must
70 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
71 are mutually exclusive. Engines may add algorithms in addition to the standard
74 Valid built-in algorithm names for private key generation are RSA, RSA-PSS, EC,
75 X25519, X448, ED25519 and ED448.
77 Valid built-in algorithm names for parameter generation (see the B<-genparam>
78 option) are DH, DSA and EC.
80 Note that the algorithm name X9.42 DH may be used as a synonym for DHX keys and
81 PKCS#3 refers to DH Keys. Some options are not shared between DH and DHX keys.
83 =item B<-pkeyopt> I<opt>:I<value>
85 Set the public key algorithm option I<opt> to I<value>. The precise set of
86 options supported depends on the public key algorithm used and its
87 implementation. See L</KEY GENERATION OPTIONS> and
88 L</PARAMETER GENERATION OPTIONS> below for more details.
92 Generate a set of parameters instead of a private key. If used this option must
93 precede any B<-algorithm>, B<-paramfile> or B<-pkeyopt> options.
95 =item B<-paramfile> I<filename>
97 Some public key algorithms generate a private key based on a set of parameters.
98 They can be supplied using this option. If this option is used the public key
99 algorithm used is determined by the parameters. If used this option must
100 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
101 are mutually exclusive.
105 Print an (unencrypted) text representation of private and public keys and
106 parameters along with the PEM or DER structure.
108 {- $OpenSSL::safe::opt_engine_item -}
110 {- $OpenSSL::safe::opt_provider_item -}
112 {- $OpenSSL::safe::opt_config_item -}
116 =head1 KEY GENERATION OPTIONS
118 The options supported by each algorithm and indeed each implementation of an
119 algorithm can vary. The options for the OpenSSL implementations are detailed
120 below. There are no key generation options defined for the X25519, X448, ED25519
123 =head2 RSA Key Generation Options
127 =item B<rsa_keygen_bits:numbits>
129 The number of bits in the generated key. If not specified 2048 is used.
131 =item B<rsa_keygen_primes:numprimes>
133 The number of primes in the generated key. If not specified 2 is used.
135 =item B<rsa_keygen_pubexp:value>
137 The RSA public exponent value. This can be a large decimal or
138 hexadecimal value if preceded by C<0x>. Default value is 65537.
142 =head2 RSA-PSS Key Generation Options
144 Note: by default an B<RSA-PSS> key has no parameter restrictions.
148 =item B<rsa_keygen_bits>:I<numbits>, B<rsa_keygen_primes>:I<numprimes>,
149 B<rsa_keygen_pubexp>:I<value>
151 These options have the same meaning as the B<RSA> algorithm.
153 =item B<rsa_pss_keygen_md>:I<digest>
155 If set the key is restricted and can only use I<digest> for signing.
157 =item B<rsa_pss_keygen_mgf1_md>:I<digest>
159 If set the key is restricted and can only use I<digest> as it's MGF1
162 =item B<rsa_pss_keygen_saltlen>:I<len>
164 If set the key is restricted and I<len> specifies the minimum salt length.
168 =head2 EC Key Generation Options
170 The EC key generation options can also be used for parameter generation.
174 =item B<ec_paramgen_curve>:I<curve>
176 The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
178 =item B<ec_param_enc>:I<encoding>
180 The encoding to use for parameters. The I<encoding> parameter must be either
181 B<named_curve> or B<explicit>. The default value is B<named_curve>.
185 =head2 DH Key Generation Options
189 =item B<group>:I<name>
191 The B<paramfile> option is not required if a named group is used here.
192 See the L</DH Parameter Generation Options> section below.
197 =head1 PARAMETER GENERATION OPTIONS
199 The options supported by each algorithm and indeed each implementation of an
200 algorithm can vary. The options for the OpenSSL implementations are detailed
203 =head2 DSA Parameter Generation Options
207 =item B<dsa_paramgen_bits>:I<numbits>
209 The number of bits in the generated prime. If not specified 2048 is used.
211 =item B<dsa_paramgen_q_bits>:I<numbits>
213 =item B<qbits>:I<numbits>
215 The number of bits in the q parameter. Must be one of 160, 224 or 256. If not
216 specified 224 is used.
218 =item B<dsa_paramgen_md>:I<digest>
220 =item B<digest>:I<digest>
222 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
223 or B<sha256>. If set, then the number of bits in B<q> will match the output size
224 of the specified digest and the B<dsa_paramgen_q_bits> parameter will be
225 ignored. If not set, then a digest will be used that gives an output matching
226 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it 224
227 or B<sha256> if it is 256.
229 =item B<properties>:I<query>
231 The I<digest> property I<query> string to use when fetching a digest from a provider.
233 =item B<type>:I<type>
235 The type of generation to use. Set this to 1 to use legacy FIPS186-2 parameter
236 generation. The default of 0 uses FIPS186-4 parameter generation.
238 =item B<gindex>:I<index>
240 The index to use for canonical generation and verification of the generator g.
241 Set this to a positive value ranging from 0..255 to use this mode. Larger values
242 will only use the bottom byte.
243 This I<index> must then be reused during key validation to verify the value of g.
244 If this value is not set then g is not verifiable. The default value is -1.
246 =item B<hexseed>:I<seed>
248 The seed I<seed> data to use instead of generating a random seed internally.
249 This should be used for testing purposes only. This will either produced fixed
250 values for the generated parameters OR it will fail if the seed did not
251 generate valid primes.
255 =head2 DH Parameter Generation Options
257 For most use cases it is recommended to use the B<group> option rather than
258 the B<type> options. Note that the B<group> option is not used by default if
259 no parameter generation options are specified.
263 =item B<group>:I<name>
265 =item B<dh_param>:I<name>
267 Use a named DH group to select constant values for the DH parameters.
268 All other options will be ignored if this value is set.
270 Valid values that are associated with the B<algorithm> of B<"DH"> are:
271 "ffdhe2048", "ffdhe3072", "ffdhe4096", "ffdhe6144", "ffdhe8192",
272 "modp_1536", "modp_2048", "modp_3072", "modp_4096", "modp_6144", "modp_8192".
274 Valid values that are associated with the B<algorithm> of B<"DHX"> are the
275 RFC5114 names "dh_1024_160", "dh_2048_224", "dh_2048_256".
277 =item B<dh_rfc5114>:I<num>
279 If this option is set, then the appropriate RFC5114 parameters are used
280 instead of generating new parameters. The value I<num> can be one of
281 1, 2 or 3 that are equivalant to using the option B<group> with one of
282 "dh_1024_160", "dh_2048_224" or "dh_2048_256".
283 All other options will be ignored if this value is set.
285 =item B<pbits>:I<numbits>
287 =item B<dh_paramgen_prime_len>:I<numbits>
289 The number of bits in the prime parameter I<p>. The default is 2048.
291 =item B<qbits>:I<numbits>
293 =item B<dh_paramgen_subprime_len>:I<numbits>
295 The number of bits in the sub prime parameter I<q>. The default is 224.
296 Only relevant if used in conjunction with the B<dh_paramgen_type> option to
297 generate DHX parameters.
299 =item B<safeprime-generator>:I<value>
301 =item B<dh_paramgen_generator>:I<value>
303 The value to use for the generator I<g>. The default is 2.
304 The B<algorithm> option must be B<"DH"> for this parameter to be used.
306 =item B<type>:I<string>
308 The type name of DH parameters to generate. Valid values are:
314 Use a safe prime generator with the option B<safeprime_generator>
315 The B<algorithm> option must be B<"DH">.
319 FIPS186-4 parameter generation.
320 The B<algorithm> option must be B<"DHX">.
324 FIPS186-4 parameter generation.
325 The B<algorithm> option must be B<"DHX">.
329 Can be used with the option B<pbits> to select one of
330 "ffdhe2048", "ffdhe3072", "ffdhe4096", "ffdhe6144" or "ffdhe8192".
331 The B<algorithm> option must be B<"DH">.
335 Selects a default type based on the B<algorithm>. This is used by the
336 OpenSSL default provider to set the type for backwards compatability.
337 If B<algorithm> is B<"DH"> then B<"generator"> is used.
338 If B<algorithm> is B<"DHX"> then B<"fips186_2"> is used.
342 =item B<dh_paramgen_type>:I<value>
344 The type of DH parameters to generate. Valid values are 0, 1, 2 or 3
345 which correspond to setting the option B<type> to
346 "generator", "fips186_2", "fips186_4" or "group".
348 =item B<digest>:I<digest>
350 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
351 or B<sha256>. If set, then the number of bits in B<qbits> will match the output
352 size of the specified digest and the B<qbits> parameter will be
353 ignored. If not set, then a digest will be used that gives an output matching
354 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it is
355 224 or B<sha256> if it is 256.
356 This is only used by "fips186_4" and "fips186_2" key generation.
358 =item B<properties>:I<query>
360 The I<digest> property I<query> string to use when fetching a digest from a provider.
361 This is only used by "fips186_4" and "fips186_2" key generation.
363 =item B<gindex>:I<index>
365 The index to use for canonical generation and verification of the generator g.
366 Set this to a positive value ranging from 0..255 to use this mode. Larger values
367 will only use the bottom byte.
368 This I<index> must then be reused during key validation to verify the value of g.
369 If this value is not set then g is not verifiable. The default value is -1.
370 This is only used by "fips186_4" and "fips186_2" key generation.
372 =item B<hexseed>:I<seed>
374 The seed I<seed> data to use instead of generating a random seed internally.
375 This should be used for testing purposes only. This will either produced fixed
376 values for the generated parameters OR it will fail if the seed did not
377 generate valid primes.
378 This is only used by "fips186_4" and "fips186_2" key generation.
382 =head2 EC Parameter Generation Options
384 The EC parameter generation options are the same as for key generation. See
385 L</EC Key Generation Options> above.
389 The use of the genpkey program is encouraged over the algorithm specific
390 utilities because additional algorithm options and ENGINE provided algorithms
395 Generate an RSA private key using default parameters:
397 openssl genpkey -algorithm RSA -out key.pem
399 Encrypt output private key using 128 bit AES and the passphrase "hello":
401 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
403 Generate a 2048 bit RSA key using 3 as the public exponent:
405 openssl genpkey -algorithm RSA -out key.pem \
406 -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3
408 Generate 2048 bit DSA parameters that can be validated: The output values for
409 gindex and seed are required for key validation purposes and are not saved to
410 the output pem file).
412 openssl genpkey -genparam -algorithm DSA -out dsap.pem -pkeyopt pbits:2048 \
413 -pkeyopt qbits:224 -pkeyopt digest:SHA256 -pkeyopt gindex:1 -text
415 Generate DSA key from parameters:
417 openssl genpkey -paramfile dsap.pem -out dsakey.pem
419 Generate 4096 bit DH Key using safe prime group ffdhe4096:
421 openssl genpkey -algorithm DH -out dhkey.pem -pkeyopt group:ffdhe4096
423 Generate 2048 bit X9.42 DH key with 256 bit subgroup using RFC5114 group3:
425 openssl genpkey -algorithm DHX -out dhkey.pem -pkeyopt dh_rfc5114:3
427 Generate a DH key using a DH parameters file:
429 openssl genpkey -paramfile dhp.pem -out dhkey.pem
431 Output DH parameters for safe prime group ffdhe2048:
433 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt group:ffdhe2048
435 Output 2048 bit X9.42 DH parameters with 224 bit subgroup using RFC5114 group2:
437 openssl genpkey -genparam -algorithm DHX -out dhp.pem -pkeyopt dh_rfc5114:2
439 Output 2048 bit X9.42 DH parameters with 224 bit subgroup using FIP186-4 keygen:
441 openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
442 -pkeyopt pbits:2048 -pkeyopt qbits:224 -pkeyopt digest:SHA256 \
443 -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:2
445 Output 1024 bit X9.42 DH parameters with 160 bit subgroup using FIP186-2 keygen:
447 openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
448 -pkeyopt pbits:1024 -pkeyopt qbits:160 -pkeyopt digest:SHA1 \
449 -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:1
451 Output 2048 bit DH parameters:
453 openssl genpkey -genparam -algorithm DH -out dhp.pem \
454 -pkeyopt dh_paramgen_prime_len:2048
456 Output 2048 bit DH parameters using a generator:
458 openssl genpkey -genparam -algorithm DH -out dhpx.pem \
459 -pkeyopt dh_paramgen_prime_len:2048 \
460 -pkeyopt dh_paramgen_type:1
462 Generate EC parameters:
464 openssl genpkey -genparam -algorithm EC -out ecp.pem \
465 -pkeyopt ec_paramgen_curve:secp384r1 \
466 -pkeyopt ec_param_enc:named_curve
468 Generate EC key from parameters:
470 openssl genpkey -paramfile ecp.pem -out eckey.pem
472 Generate EC key directly:
474 openssl genpkey -algorithm EC -out eckey.pem \
475 -pkeyopt ec_paramgen_curve:P-384 \
476 -pkeyopt ec_param_enc:named_curve
478 Generate an X25519 private key:
480 openssl genpkey -algorithm X25519 -out xkey.pem
482 Generate an ED448 private key:
484 openssl genpkey -algorithm ED448 -out xkey.pem
488 The ability to use NIST curve names, and to generate an EC key directly,
489 were added in OpenSSL 1.0.2.
490 The ability to generate X25519 keys was added in OpenSSL 1.1.0.
491 The ability to generate X448, ED25519 and ED448 keys was added in OpenSSL 1.1.1.
493 The B<-engine> option was deprecated in OpenSSL 3.0.
497 Copyright 2006-2021 The OpenSSL Project Authors. All Rights Reserved.
499 Licensed under the Apache License 2.0 (the "License"). You may not use
500 this file except in compliance with the License. You can obtain a copy
501 in the file LICENSE in the source distribution or at
502 L<https://www.openssl.org/source/license.html>.