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 -}
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, except when B<-genparam> is given; the default is B<PEM>.
51 See L<openssl-format-options(1)> for details.
53 When B<-genparam> is given, B<-outform> is ignored.
57 Do not output "status dots" while generating keys.
61 The output file password source. For more information about the format of I<arg>
62 see L<openssl-passphrase-options(1)>.
66 This option encrypts the private key with the supplied cipher. Any algorithm
67 name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>.
69 =item B<-algorithm> I<alg>
71 Public key algorithm to use such as RSA, DSA, DH or DHX. If used this option must
72 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
73 are mutually exclusive. Engines may add algorithms in addition to the standard
76 Valid built-in algorithm names for private key generation are RSA, RSA-PSS, EC,
77 X25519, X448, ED25519 and ED448.
79 Valid built-in algorithm names for parameter generation (see the B<-genparam>
80 option) are DH, DSA and EC.
82 Note that the algorithm name X9.42 DH may be used as a synonym for DHX keys and
83 PKCS#3 refers to DH Keys. Some options are not shared between DH and DHX keys.
85 =item B<-pkeyopt> I<opt>:I<value>
87 Set the public key algorithm option I<opt> to I<value>. The precise set of
88 options supported depends on the public key algorithm used and its
89 implementation. See L</KEY GENERATION OPTIONS> and
90 L</PARAMETER GENERATION OPTIONS> below for more details.
94 Generate a set of parameters instead of a private key. If used this option must
95 precede any B<-algorithm>, B<-paramfile> or B<-pkeyopt> options.
97 =item B<-paramfile> I<filename>
99 Some public key algorithms generate a private key based on a set of parameters.
100 They can be supplied using this option. If this option is used the public key
101 algorithm used is determined by the parameters. If used this option must
102 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
103 are mutually exclusive.
107 Print an (unencrypted) text representation of private and public keys and
108 parameters along with the PEM or DER structure.
110 {- $OpenSSL::safe::opt_engine_item -}
112 {- $OpenSSL::safe::opt_provider_item -}
114 {- $OpenSSL::safe::opt_config_item -}
118 =head1 KEY GENERATION OPTIONS
120 The options supported by each algorithm and indeed each implementation of an
121 algorithm can vary. The options for the OpenSSL implementations are detailed
122 below. There are no key generation options defined for the X25519, X448, ED25519
125 =head2 RSA Key Generation Options
129 =item B<rsa_keygen_bits:numbits>
131 The number of bits in the generated key. If not specified 2048 is used.
133 =item B<rsa_keygen_primes:numprimes>
135 The number of primes in the generated key. If not specified 2 is used.
137 =item B<rsa_keygen_pubexp:value>
139 The RSA public exponent value. This can be a large decimal or
140 hexadecimal value if preceded by C<0x>. Default value is 65537.
144 =head2 RSA-PSS Key Generation Options
146 Note: by default an B<RSA-PSS> key has no parameter restrictions.
150 =item B<rsa_keygen_bits>:I<numbits>, B<rsa_keygen_primes>:I<numprimes>,
151 B<rsa_keygen_pubexp>:I<value>
153 These options have the same meaning as the B<RSA> algorithm.
155 =item B<rsa_pss_keygen_md>:I<digest>
157 If set the key is restricted and can only use I<digest> for signing.
159 =item B<rsa_pss_keygen_mgf1_md>:I<digest>
161 If set the key is restricted and can only use I<digest> as it's MGF1
164 =item B<rsa_pss_keygen_saltlen>:I<len>
166 If set the key is restricted and I<len> specifies the minimum salt length.
170 =head2 EC Key Generation Options
172 The EC key generation options can also be used for parameter generation.
176 =item B<ec_paramgen_curve>:I<curve>
178 The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
180 =item B<ec_param_enc>:I<encoding>
182 The encoding to use for parameters. The I<encoding> parameter must be either
183 B<named_curve> or B<explicit>. The default value is B<named_curve>.
187 =head2 DH Key Generation Options
191 =item B<group>:I<name>
193 The B<paramfile> option is not required if a named group is used here.
194 See the L</DH Parameter Generation Options> section below.
199 =head1 PARAMETER GENERATION OPTIONS
201 The options supported by each algorithm and indeed each implementation of an
202 algorithm can vary. The options for the OpenSSL implementations are detailed
205 =head2 DSA Parameter Generation Options
209 =item B<dsa_paramgen_bits>:I<numbits>
211 The number of bits in the generated prime. If not specified 2048 is used.
213 =item B<dsa_paramgen_q_bits>:I<numbits>
215 =item B<qbits>:I<numbits>
217 The number of bits in the q parameter. Must be one of 160, 224 or 256. If not
218 specified 224 is used.
220 =item B<dsa_paramgen_md>:I<digest>
222 =item B<digest>:I<digest>
224 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
225 or B<sha256>. If set, then the number of bits in B<q> will match the output size
226 of the specified digest and the B<dsa_paramgen_q_bits> parameter will be
227 ignored. If not set, then a digest will be used that gives an output matching
228 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it 224
229 or B<sha256> if it is 256.
231 =item B<properties>:I<query>
233 The I<digest> property I<query> string to use when fetching a digest from a provider.
235 =item B<type>:I<type>
237 The type of generation to use. Set this to 1 to use legacy FIPS186-2 parameter
238 generation. The default of 0 uses FIPS186-4 parameter generation.
240 =item B<gindex>:I<index>
242 The index to use for canonical generation and verification of the generator g.
243 Set this to a positive value ranging from 0..255 to use this mode. Larger values
244 will only use the bottom byte.
245 This I<index> must then be reused during key validation to verify the value of g.
246 If this value is not set then g is not verifiable. The default value is -1.
248 =item B<hexseed>:I<seed>
250 The seed I<seed> data to use instead of generating a random seed internally.
251 This should be used for testing purposes only. This will either produced fixed
252 values for the generated parameters OR it will fail if the seed did not
253 generate valid primes.
257 =head2 DH Parameter Generation Options
259 For most use cases it is recommended to use the B<group> option rather than
260 the B<type> options. Note that the B<group> option is not used by default if
261 no parameter generation options are specified.
265 =item B<group>:I<name>
267 =item B<dh_param>:I<name>
269 Use a named DH group to select constant values for the DH parameters.
270 All other options will be ignored if this value is set.
272 Valid values that are associated with the B<algorithm> of B<"DH"> are:
273 "ffdhe2048", "ffdhe3072", "ffdhe4096", "ffdhe6144", "ffdhe8192",
274 "modp_1536", "modp_2048", "modp_3072", "modp_4096", "modp_6144", "modp_8192".
276 Valid values that are associated with the B<algorithm> of B<"DHX"> are the
277 RFC5114 names "dh_1024_160", "dh_2048_224", "dh_2048_256".
279 =item B<dh_rfc5114>:I<num>
281 If this option is set, then the appropriate RFC5114 parameters are used
282 instead of generating new parameters. The value I<num> can be one of
283 1, 2 or 3 that are equivalant to using the option B<group> with one of
284 "dh_1024_160", "dh_2048_224" or "dh_2048_256".
285 All other options will be ignored if this value is set.
287 =item B<pbits>:I<numbits>
289 =item B<dh_paramgen_prime_len>:I<numbits>
291 The number of bits in the prime parameter I<p>. The default is 2048.
293 =item B<qbits>:I<numbits>
295 =item B<dh_paramgen_subprime_len>:I<numbits>
297 The number of bits in the sub prime parameter I<q>. The default is 224.
298 Only relevant if used in conjunction with the B<dh_paramgen_type> option to
299 generate DHX parameters.
301 =item B<safeprime-generator>:I<value>
303 =item B<dh_paramgen_generator>:I<value>
305 The value to use for the generator I<g>. The default is 2.
306 The B<algorithm> option must be B<"DH"> for this parameter to be used.
308 =item B<type>:I<string>
310 The type name of DH parameters to generate. Valid values are:
316 Use a safe prime generator with the option B<safeprime_generator>
317 The B<algorithm> option must be B<"DH">.
321 FIPS186-4 parameter generation.
322 The B<algorithm> option must be B<"DHX">.
326 FIPS186-4 parameter generation.
327 The B<algorithm> option must be B<"DHX">.
331 Can be used with the option B<pbits> to select one of
332 "ffdhe2048", "ffdhe3072", "ffdhe4096", "ffdhe6144" or "ffdhe8192".
333 The B<algorithm> option must be B<"DH">.
337 Selects a default type based on the B<algorithm>. This is used by the
338 OpenSSL default provider to set the type for backwards compatability.
339 If B<algorithm> is B<"DH"> then B<"generator"> is used.
340 If B<algorithm> is B<"DHX"> then B<"fips186_2"> is used.
344 =item B<dh_paramgen_type>:I<value>
346 The type of DH parameters to generate. Valid values are 0, 1, 2 or 3
347 which correspond to setting the option B<type> to
348 "generator", "fips186_2", "fips186_4" or "group".
350 =item B<digest>:I<digest>
352 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
353 or B<sha256>. If set, then the number of bits in B<qbits> will match the output
354 size of the specified digest and the B<qbits> parameter will be
355 ignored. If not set, then a digest will be used that gives an output matching
356 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it is
357 224 or B<sha256> if it is 256.
358 This is only used by "fips186_4" and "fips186_2" key generation.
360 =item B<properties>:I<query>
362 The I<digest> property I<query> string to use when fetching a digest from a provider.
363 This is only used by "fips186_4" and "fips186_2" key generation.
365 =item B<gindex>:I<index>
367 The index to use for canonical generation and verification of the generator g.
368 Set this to a positive value ranging from 0..255 to use this mode. Larger values
369 will only use the bottom byte.
370 This I<index> must then be reused during key validation to verify the value of g.
371 If this value is not set then g is not verifiable. The default value is -1.
372 This is only used by "fips186_4" and "fips186_2" key generation.
374 =item B<hexseed>:I<seed>
376 The seed I<seed> data to use instead of generating a random seed internally.
377 This should be used for testing purposes only. This will either produced fixed
378 values for the generated parameters OR it will fail if the seed did not
379 generate valid primes.
380 This is only used by "fips186_4" and "fips186_2" key generation.
384 =head2 EC Parameter Generation Options
386 The EC parameter generation options are the same as for key generation. See
387 L</EC Key Generation Options> above.
391 The use of the genpkey program is encouraged over the algorithm specific
392 utilities because additional algorithm options and ENGINE provided algorithms
397 Generate an RSA private key using default parameters:
399 openssl genpkey -algorithm RSA -out key.pem
401 Encrypt output private key using 128 bit AES and the passphrase "hello":
403 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
405 Generate a 2048 bit RSA key using 3 as the public exponent:
407 openssl genpkey -algorithm RSA -out key.pem \
408 -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3
410 Generate 2048 bit DSA parameters that can be validated: The output values for
411 gindex and seed are required for key validation purposes and are not saved to
412 the output pem file).
414 openssl genpkey -genparam -algorithm DSA -out dsap.pem -pkeyopt pbits:2048 \
415 -pkeyopt qbits:224 -pkeyopt digest:SHA256 -pkeyopt gindex:1 -text
417 Generate DSA key from parameters:
419 openssl genpkey -paramfile dsap.pem -out dsakey.pem
421 Generate 4096 bit DH Key using safe prime group ffdhe4096:
423 openssl genpkey -algorithm DH -out dhkey.pem -pkeyopt group:ffdhe4096
425 Generate 2048 bit X9.42 DH key with 256 bit subgroup using RFC5114 group3:
427 openssl genpkey -algorithm DHX -out dhkey.pem -pkeyopt dh_rfc5114:3
429 Generate a DH key using a DH parameters file:
431 openssl genpkey -paramfile dhp.pem -out dhkey.pem
433 Output DH parameters for safe prime group ffdhe2048:
435 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt group:ffdhe2048
437 Output 2048 bit X9.42 DH parameters with 224 bit subgroup using RFC5114 group2:
439 openssl genpkey -genparam -algorithm DHX -out dhp.pem -pkeyopt dh_rfc5114:2
441 Output 2048 bit X9.42 DH parameters with 224 bit subgroup using FIP186-4 keygen:
443 openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
444 -pkeyopt pbits:2048 -pkeyopt qbits:224 -pkeyopt digest:SHA256 \
445 -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:2
447 Output 1024 bit X9.42 DH parameters with 160 bit subgroup using FIP186-2 keygen:
449 openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
450 -pkeyopt pbits:1024 -pkeyopt qbits:160 -pkeyopt digest:SHA1 \
451 -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:1
453 Output 2048 bit DH parameters:
455 openssl genpkey -genparam -algorithm DH -out dhp.pem \
456 -pkeyopt dh_paramgen_prime_len:2048
458 Output 2048 bit DH parameters using a generator:
460 openssl genpkey -genparam -algorithm DH -out dhpx.pem \
461 -pkeyopt dh_paramgen_prime_len:2048 \
462 -pkeyopt dh_paramgen_type:1
464 Generate EC parameters:
466 openssl genpkey -genparam -algorithm EC -out ecp.pem \
467 -pkeyopt ec_paramgen_curve:secp384r1 \
468 -pkeyopt ec_param_enc:named_curve
470 Generate EC key from parameters:
472 openssl genpkey -paramfile ecp.pem -out eckey.pem
474 Generate EC key directly:
476 openssl genpkey -algorithm EC -out eckey.pem \
477 -pkeyopt ec_paramgen_curve:P-384 \
478 -pkeyopt ec_param_enc:named_curve
480 Generate an X25519 private key:
482 openssl genpkey -algorithm X25519 -out xkey.pem
484 Generate an ED448 private key:
486 openssl genpkey -algorithm ED448 -out xkey.pem
490 The ability to use NIST curve names, and to generate an EC key directly,
491 were added in OpenSSL 1.0.2.
492 The ability to generate X25519 keys was added in OpenSSL 1.1.0.
493 The ability to generate X448, ED25519 and ED448 keys was added in OpenSSL 1.1.1.
495 The B<-engine> option was deprecated in OpenSSL 3.0.
499 Copyright 2006-2021 The OpenSSL Project Authors. All Rights Reserved.
501 Licensed under the Apache License 2.0 (the "License"). You may not use
502 this file except in compliance with the License. You can obtain a copy
503 in the file LICENSE in the source distribution or at
504 L<https://www.openssl.org/source/license.html>.