4 {- join("\n", @autowarntext) -}
10 openssl-genpkey - generate a private key or key pair
17 [B<-outpubkey> I<filename>]
18 [B<-outform> B<DER>|B<PEM>]
23 [B<-paramfile> I<file>]
24 [B<-algorithm> I<alg>]
25 [B<-pkeyopt> I<opt>:I<value>]
28 {- $OpenSSL::safe::opt_r_synopsis -}
29 {- $OpenSSL::safe::opt_engine_synopsis -}
30 {- $OpenSSL::safe::opt_provider_synopsis -}
31 {- $OpenSSL::safe::opt_config_synopsis -}
35 This command generates a private key or key pair.
43 Print out a usage message.
45 =item B<-out> I<filename>
47 Output the private key to the specified file. If this argument is not
48 specified then standard output is used.
50 =item B<-outpubkey> I<filename>
52 Output the public key to the specified file. If this argument is not
53 specified then the public key is not output.
55 =item B<-outform> B<DER>|B<PEM>
57 The output format, except when B<-genparam> is given; the default is B<PEM>.
58 See L<openssl-format-options(1)> for details.
60 When B<-genparam> is given, B<-outform> is ignored.
64 Output "status dots" while generating keys.
68 Do not output "status dots" while generating keys.
72 The output file password source. For more information about the format of I<arg>
73 see L<openssl-passphrase-options(1)>.
77 This option encrypts the private key with the supplied cipher. Any algorithm
78 name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>.
80 =item B<-algorithm> I<alg>
82 Public key algorithm to use such as RSA, DSA, DH or DHX. If used this option must
83 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
84 are mutually exclusive. Engines or providers may add algorithms in addition to
85 the standard built-in ones.
87 Valid built-in algorithm names for private key generation are RSA, RSA-PSS, EC,
88 X25519, X448, ED25519 and ED448.
90 Valid built-in algorithm names for parameter generation (see the B<-genparam>
91 option) are DH, DSA and EC.
93 Note that the algorithm name X9.42 DH may be used as a synonym for DHX keys and
94 PKCS#3 refers to DH Keys. Some options are not shared between DH and DHX keys.
96 =item B<-pkeyopt> I<opt>:I<value>
98 Set the public key algorithm option I<opt> to I<value>. The precise set of
99 options supported depends on the public key algorithm used and its
100 implementation. See L</KEY GENERATION OPTIONS> and
101 L</PARAMETER GENERATION OPTIONS> below for more details.
103 To list the possible I<opt> values for an algorithm use:
104 B<openssl> B<genpkey> -algorithm XXX -help
108 Generate a set of parameters instead of a private key. If used this option must
109 precede any B<-algorithm>, B<-paramfile> or B<-pkeyopt> options.
111 =item B<-paramfile> I<filename>
113 Some public key algorithms generate a private key based on a set of parameters.
114 They can be supplied using this option. If this option is used the public key
115 algorithm used is determined by the parameters. If used this option must
116 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
117 are mutually exclusive.
121 Print an (unencrypted) text representation of private and public keys and
122 parameters along with the PEM or DER structure.
124 {- $OpenSSL::safe::opt_r_item -}
126 {- $OpenSSL::safe::opt_engine_item -}
128 {- $OpenSSL::safe::opt_provider_item -}
130 {- $OpenSSL::safe::opt_config_item -}
134 =head1 KEY GENERATION OPTIONS
136 The options supported by each algorithm and indeed each implementation of an
137 algorithm can vary. The options for the OpenSSL implementations are detailed
138 below. There are no key generation options defined for the X25519, X448, ED25519
141 =head2 RSA Key Generation Options
145 =item B<rsa_keygen_bits:numbits>
147 The number of bits in the generated key. If not specified 2048 is used.
149 =item B<rsa_keygen_primes:numprimes>
151 The number of primes in the generated key. If not specified 2 is used.
153 =item B<rsa_keygen_pubexp:value>
155 The RSA public exponent value. This can be a large decimal or
156 hexadecimal value if preceded by C<0x>. Default value is 65537.
160 =head2 RSA-PSS Key Generation Options
162 Note: by default an B<RSA-PSS> key has no parameter restrictions.
166 =item B<rsa_keygen_bits>:I<numbits>, B<rsa_keygen_primes>:I<numprimes>,
167 B<rsa_keygen_pubexp>:I<value>
169 These options have the same meaning as the B<RSA> algorithm.
171 =item B<rsa_pss_keygen_md>:I<digest>
173 If set the key is restricted and can only use I<digest> for signing.
175 =item B<rsa_pss_keygen_mgf1_md>:I<digest>
177 If set the key is restricted and can only use I<digest> as it's MGF1
180 =item B<rsa_pss_keygen_saltlen>:I<len>
182 If set the key is restricted and I<len> specifies the minimum salt length.
186 =head2 EC Key Generation Options
188 The EC key generation options can also be used for parameter generation.
192 =item B<ec_paramgen_curve>:I<curve>
194 The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
196 =item B<ec_param_enc>:I<encoding>
198 The encoding to use for parameters. The I<encoding> parameter must be either
199 B<named_curve> or B<explicit>. The default value is B<named_curve>.
203 =head2 DH Key Generation Options
207 =item B<group>:I<name>
209 The B<paramfile> option is not required if a named group is used here.
210 See the L</DH Parameter Generation Options> section below.
215 =head1 PARAMETER GENERATION OPTIONS
217 The options supported by each algorithm and indeed each implementation of an
218 algorithm can vary. The options for the OpenSSL implementations are detailed
221 =head2 DSA Parameter Generation Options
225 =item B<dsa_paramgen_bits>:I<numbits>
227 The number of bits in the generated prime. If not specified 2048 is used.
229 =item B<dsa_paramgen_q_bits>:I<numbits>
231 =item B<qbits>:I<numbits>
233 The number of bits in the q parameter. Must be one of 160, 224 or 256. If not
234 specified 224 is used.
236 =item B<dsa_paramgen_md>:I<digest>
238 =item B<digest>:I<digest>
240 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
241 or B<sha256>. If set, then the number of bits in B<q> will match the output size
242 of the specified digest and the B<dsa_paramgen_q_bits> parameter will be
243 ignored. If not set, then a digest will be used that gives an output matching
244 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it 224
245 or B<sha256> if it is 256.
247 =item B<properties>:I<query>
249 The I<digest> property I<query> string to use when fetching a digest from a provider.
251 =item B<type>:I<type>
253 The type of generation to use. Set this to 1 to use legacy FIPS186-2 parameter
254 generation. The default of 0 uses FIPS186-4 parameter generation.
256 =item B<gindex>:I<index>
258 The index to use for canonical generation and verification of the generator g.
259 Set this to a positive value ranging from 0..255 to use this mode. Larger values
260 will only use the bottom byte.
261 This I<index> must then be reused during key validation to verify the value of g.
262 If this value is not set then g is not verifiable. The default value is -1.
264 =item B<hexseed>:I<seed>
266 The seed I<seed> data to use instead of generating a random seed internally.
267 This should be used for testing purposes only. This will either produced fixed
268 values for the generated parameters OR it will fail if the seed did not
269 generate valid primes.
273 =head2 DH Parameter Generation Options
275 For most use cases it is recommended to use the B<group> option rather than
276 the B<type> options. Note that the B<group> option is not used by default if
277 no parameter generation options are specified.
281 =item B<group>:I<name>
283 =item B<dh_param>:I<name>
285 Use a named DH group to select constant values for the DH parameters.
286 All other options will be ignored if this value is set.
288 Valid values that are associated with the B<algorithm> of B<"DH"> are:
289 "ffdhe2048", "ffdhe3072", "ffdhe4096", "ffdhe6144", "ffdhe8192",
290 "modp_1536", "modp_2048", "modp_3072", "modp_4096", "modp_6144", "modp_8192".
292 Valid values that are associated with the B<algorithm> of B<"DHX"> are the
293 RFC5114 names "dh_1024_160", "dh_2048_224", "dh_2048_256".
295 =item B<dh_rfc5114>:I<num>
297 If this option is set, then the appropriate RFC5114 parameters are used
298 instead of generating new parameters. The value I<num> can be one of
299 1, 2 or 3 that are equivalent to using the option B<group> with one of
300 "dh_1024_160", "dh_2048_224" or "dh_2048_256".
301 All other options will be ignored if this value is set.
303 =item B<pbits>:I<numbits>
305 =item B<dh_paramgen_prime_len>:I<numbits>
307 The number of bits in the prime parameter I<p>. The default is 2048.
309 =item B<qbits>:I<numbits>
311 =item B<dh_paramgen_subprime_len>:I<numbits>
313 The number of bits in the sub prime parameter I<q>. The default is 224.
314 Only relevant if used in conjunction with the B<dh_paramgen_type> option to
315 generate DHX parameters.
317 =item B<safeprime-generator>:I<value>
319 =item B<dh_paramgen_generator>:I<value>
321 The value to use for the generator I<g>. The default is 2.
322 The B<algorithm> option must be B<"DH"> for this parameter to be used.
324 =item B<type>:I<string>
326 The type name of DH parameters to generate. Valid values are:
332 Use a safe prime generator with the option B<safeprime_generator>
333 The B<algorithm> option must be B<"DH">.
337 FIPS186-4 parameter generation.
338 The B<algorithm> option must be B<"DHX">.
342 FIPS186-4 parameter generation.
343 The B<algorithm> option must be B<"DHX">.
347 Can be used with the option B<pbits> to select one of
348 "ffdhe2048", "ffdhe3072", "ffdhe4096", "ffdhe6144" or "ffdhe8192".
349 The B<algorithm> option must be B<"DH">.
353 Selects a default type based on the B<algorithm>. This is used by the
354 OpenSSL default provider to set the type for backwards compatibility.
355 If B<algorithm> is B<"DH"> then B<"generator"> is used.
356 If B<algorithm> is B<"DHX"> then B<"fips186_2"> is used.
360 =item B<dh_paramgen_type>:I<value>
362 The type of DH parameters to generate. Valid values are 0, 1, 2 or 3
363 which correspond to setting the option B<type> to
364 "generator", "fips186_2", "fips186_4" or "group".
366 =item B<digest>:I<digest>
368 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
369 or B<sha256>. If set, then the number of bits in B<qbits> will match the output
370 size of the specified digest and the B<qbits> parameter will be
371 ignored. If not set, then a digest will be used that gives an output matching
372 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it is
373 224 or B<sha256> if it is 256.
374 This is only used by "fips186_4" and "fips186_2" key generation.
376 =item B<properties>:I<query>
378 The I<digest> property I<query> string to use when fetching a digest from a provider.
379 This is only used by "fips186_4" and "fips186_2" key generation.
381 =item B<gindex>:I<index>
383 The index to use for canonical generation and verification of the generator g.
384 Set this to a positive value ranging from 0..255 to use this mode. Larger values
385 will only use the bottom byte.
386 This I<index> must then be reused during key validation to verify the value of g.
387 If this value is not set then g is not verifiable. The default value is -1.
388 This is only used by "fips186_4" and "fips186_2" key generation.
390 =item B<hexseed>:I<seed>
392 The seed I<seed> data to use instead of generating a random seed internally.
393 This should be used for testing purposes only. This will either produced fixed
394 values for the generated parameters OR it will fail if the seed did not
395 generate valid primes.
396 This is only used by "fips186_4" and "fips186_2" key generation.
400 =head2 EC Parameter Generation Options
402 The EC parameter generation options are the same as for key generation. See
403 L</EC Key Generation Options> above.
407 The use of the genpkey program is encouraged over the algorithm specific
408 utilities because additional algorithm options and ENGINE provided algorithms
413 Generate an RSA private key using default parameters:
415 openssl genpkey -algorithm RSA -out key.pem
417 Encrypt output private key using 128 bit AES and the passphrase "hello":
419 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
421 Generate a 2048 bit RSA key using 3 as the public exponent:
423 openssl genpkey -algorithm RSA -out key.pem \
424 -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3
426 Generate 2048 bit DSA parameters that can be validated: The output values for
427 gindex and seed are required for key validation purposes and are not saved to
428 the output pem file).
430 openssl genpkey -genparam -algorithm DSA -out dsap.pem -pkeyopt pbits:2048 \
431 -pkeyopt qbits:224 -pkeyopt digest:SHA256 -pkeyopt gindex:1 -text
433 Generate DSA key from parameters:
435 openssl genpkey -paramfile dsap.pem -out dsakey.pem
437 Generate 4096 bit DH Key using safe prime group ffdhe4096:
439 openssl genpkey -algorithm DH -out dhkey.pem -pkeyopt group:ffdhe4096
441 Generate 2048 bit X9.42 DH key with 256 bit subgroup using RFC5114 group3:
443 openssl genpkey -algorithm DHX -out dhkey.pem -pkeyopt dh_rfc5114:3
445 Generate a DH key using a DH parameters file:
447 openssl genpkey -paramfile dhp.pem -out dhkey.pem
449 Output DH parameters for safe prime group ffdhe2048:
451 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt group:ffdhe2048
453 Output 2048 bit X9.42 DH parameters with 224 bit subgroup using RFC5114 group2:
455 openssl genpkey -genparam -algorithm DHX -out dhp.pem -pkeyopt dh_rfc5114:2
457 Output 2048 bit X9.42 DH parameters with 224 bit subgroup using FIP186-4 keygen:
459 openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
460 -pkeyopt pbits:2048 -pkeyopt qbits:224 -pkeyopt digest:SHA256 \
461 -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:2
463 Output 1024 bit X9.42 DH parameters with 160 bit subgroup using FIP186-2 keygen:
465 openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
466 -pkeyopt pbits:1024 -pkeyopt qbits:160 -pkeyopt digest:SHA1 \
467 -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:1
469 Output 2048 bit DH parameters:
471 openssl genpkey -genparam -algorithm DH -out dhp.pem \
472 -pkeyopt dh_paramgen_prime_len:2048
474 Output 2048 bit DH parameters using a generator:
476 openssl genpkey -genparam -algorithm DH -out dhpx.pem \
477 -pkeyopt dh_paramgen_prime_len:2048 \
478 -pkeyopt dh_paramgen_type:1
480 Generate EC parameters:
482 openssl genpkey -genparam -algorithm EC -out ecp.pem \
483 -pkeyopt ec_paramgen_curve:secp384r1 \
484 -pkeyopt ec_param_enc:named_curve
486 Generate EC key from parameters:
488 openssl genpkey -paramfile ecp.pem -out eckey.pem
490 Generate EC key directly:
492 openssl genpkey -algorithm EC -out eckey.pem \
493 -pkeyopt ec_paramgen_curve:P-384 \
494 -pkeyopt ec_param_enc:named_curve
496 Generate an X25519 private key:
498 openssl genpkey -algorithm X25519 -out xkey.pem
500 Generate an ED448 private key:
502 openssl genpkey -algorithm ED448 -out xkey.pem
506 The ability to use NIST curve names, and to generate an EC key directly,
507 were added in OpenSSL 1.0.2.
508 The ability to generate X25519 keys was added in OpenSSL 1.1.0.
509 The ability to generate X448, ED25519 and ED448 keys was added in OpenSSL 1.1.1.
511 The B<-engine> option was deprecated in OpenSSL 3.0.
515 Copyright 2006-2024 The OpenSSL Project Authors. All Rights Reserved.
517 Licensed under the Apache License 2.0 (the "License"). You may not use
518 this file except in compliance with the License. You can obtain a copy
519 in the file LICENSE in the source distribution or at
520 L<https://www.openssl.org/source/license.html>.