1OPENSSL-GENPKEY(1ossl) OpenSSL OPENSSL-GENPKEY(1ossl)
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6 openssl-genpkey - generate a private key
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9 openssl genpkey [-help] [-out filename] [-outform DER|PEM] [-quiet]
10 [-pass arg] [-cipher] [-paramfile file] [-algorithm alg] [-pkeyopt
11 opt:value] [-genparam] [-text] [-engine id] [-provider name]
12 [-provider-path path] [-propquery propq] [-config configfile]
13
15 This command generates a private key.
16
18 -help
19 Print out a usage message.
20 -out filename
22 Output the key to the specified file. If this argument is not
23 specified then standard output is used.
24 -outform DER|PEM
26 The output format, except when -genparam is given; the default is
27 PEM. See openssl-format-options(1) for details.
28 When -genparam is given, -outform is ignored.
30 -quiet
32 Do not output "status dots" while generating keys.
33 -pass arg
35 The output file password source. For more information about the
36 format of arg see openssl-passphrase-options(1).
37 -cipher
39 This option encrypts the private key with the supplied cipher. Any
40 algorithm name accepted by EVP_get_cipherbyname() is acceptable
41 such as des3.
42 -algorithm alg
44 Public key algorithm to use such as RSA, DSA, DH or DHX. If used
45 this option must precede any -pkeyopt options. The options
46 -paramfile and -algorithm are mutually exclusive. Engines may add
47 algorithms in addition to the standard built-in ones.
48 Valid built-in algorithm names for private key generation are RSA,
50 RSA-PSS, EC, X25519, X448, ED25519 and ED448.
51 Valid built-in algorithm names for parameter generation (see the
53 -genparam option) are DH, DSA and EC.
54 Note that the algorithm name X9.42 DH may be used as a synonym for
56 DHX keys and PKCS#3 refers to DH Keys. Some options are not shared
57 between DH and DHX keys.
58 -pkeyopt opt:value
60 Set the public key algorithm option opt to value. The precise set
61 of options supported depends on the public key algorithm used and
62 its implementation. See "KEY GENERATION OPTIONS" and "PARAMETER
63 GENERATION OPTIONS" below for more details.
64 -genparam
66 Generate a set of parameters instead of a private key. If used this
67 option must precede any -algorithm, -paramfile or -pkeyopt options.
68 -paramfile filename
70 Some public key algorithms generate a private key based on a set of
71 parameters. They can be supplied using this option. If this option
72 is used the public key algorithm used is determined by the
73 parameters. If used this option must precede any -pkeyopt options.
74 The options -paramfile and -algorithm are mutually exclusive.
75 -text
77 Print an (unencrypted) text representation of private and public
78 keys and parameters along with the PEM or DER structure.
79 -engine id
81 See "Engine Options" in openssl(1). This option is deprecated.
82 -provider name
84 -provider-path path
85 -propquery propq
86 See "Provider Options" in openssl(1), provider(7), and property(7).
87 -config configfile
89 See "Configuration Option" in openssl(1).
90
92 The options supported by each algorithm and indeed each implementation
93 of an algorithm can vary. The options for the OpenSSL implementations
94 are detailed below. There are no key generation options defined for the
95 X25519, X448, ED25519 or ED448 algorithms.
96 RSA Key Generation Options
98 rsa_keygen_bits:numbits
99 The number of bits in the generated key. If not specified 2048 is
100 used.
101 rsa_keygen_primes:numprimes
103 The number of primes in the generated key. If not specified 2 is
104 used.
105 rsa_keygen_pubexp:value
107 The RSA public exponent value. This can be a large decimal or
108 hexadecimal value if preceded by "0x". Default value is 65537.
109 RSA-PSS Key Generation Options
111 Note: by default an RSA-PSS key has no parameter restrictions.
112 rsa_keygen_bits:numbits, rsa_keygen_primes:numprimes,
114 rsa_keygen_pubexp:value
115 These options have the same meaning as the RSA algorithm.
116 rsa_pss_keygen_md:digest
118 If set the key is restricted and can only use digest for signing.
119 rsa_pss_keygen_mgf1_md:digest
121 If set the key is restricted and can only use digest as it's MGF1
122 parameter.
123 rsa_pss_keygen_saltlen:len
125 If set the key is restricted and len specifies the minimum salt
126 length.
127 EC Key Generation Options
129 The EC key generation options can also be used for parameter
130 generation.
131 ec_paramgen_curve:curve
133 The EC curve to use. OpenSSL supports NIST curve names such as
134 "P-256".
135 ec_param_enc:encoding
137 The encoding to use for parameters. The encoding parameter must be
138 either named_curve or explicit. The default value is named_curve.
139 DH Key Generation Options
141 group:name
142 The paramfile option is not required if a named group is used here.
143 See the "DH Parameter Generation Options" section below.
144
146 The options supported by each algorithm and indeed each implementation
147 of an algorithm can vary. The options for the OpenSSL implementations
148 are detailed below.
149 DSA Parameter Generation Options
151 dsa_paramgen_bits:numbits
152 The number of bits in the generated prime. If not specified 2048 is
153 used.
154 dsa_paramgen_q_bits:numbits
156 qbits:numbits
157 The number of bits in the q parameter. Must be one of 160, 224 or
158 256. If not specified 224 is used.
159 dsa_paramgen_md:digest
161 digest:digest
162 The digest to use during parameter generation. Must be one of sha1,
163 sha224 or sha256. If set, then the number of bits in q will match
164 the output size of the specified digest and the dsa_paramgen_q_bits
165 parameter will be ignored. If not set, then a digest will be used
166 that gives an output matching the number of bits in q, i.e. sha1 if
167 q length is 160, sha224 if it 224 or sha256 if it is 256.
168 properties:query
170 The digest property query string to use when fetching a digest from
171 a provider.
172 type:type
174 The type of generation to use. Set this to 1 to use legacy
175 FIPS186-2 parameter generation. The default of 0 uses FIPS186-4
176 parameter generation.
177 gindex:index
179 The index to use for canonical generation and verification of the
180 generator g. Set this to a positive value ranging from 0..255 to
181 use this mode. Larger values will only use the bottom byte. This
182 index must then be reused during key validation to verify the value
183 of g. If this value is not set then g is not verifiable. The
184 default value is -1.
185 hexseed:seed
187 The seed seed data to use instead of generating a random seed
188 internally. This should be used for testing purposes only. This
189 will either produced fixed values for the generated parameters OR
190 it will fail if the seed did not generate valid primes.
191 DH Parameter Generation Options
193 For most use cases it is recommended to use the group option rather
194 than the type options. Note that the group option is not used by
195 default if no parameter generation options are specified.
196 group:name
198 dh_param:name
199 Use a named DH group to select constant values for the DH
200 parameters. All other options will be ignored if this value is
201 set.
202 Valid values that are associated with the algorithm of "DH" are:
204 "ffdhe2048", "ffdhe3072", "ffdhe4096", "ffdhe6144", "ffdhe8192",
205 "modp_1536", "modp_2048", "modp_3072", "modp_4096", "modp_6144",
206 "modp_8192".
207 Valid values that are associated with the algorithm of "DHX" are
209 the RFC5114 names "dh_1024_160", "dh_2048_224", "dh_2048_256".
210 dh_rfc5114:num
212 If this option is set, then the appropriate RFC5114 parameters are
213 used instead of generating new parameters. The value num can be one
214 of 1, 2 or 3 that are equivalant to using the option group with one
215 of "dh_1024_160", "dh_2048_224" or "dh_2048_256". All other
216 options will be ignored if this value is set.
217 pbits:numbits
219 dh_paramgen_prime_len:numbits
220 The number of bits in the prime parameter p. The default is 2048.
221 qbits:numbits
223 dh_paramgen_subprime_len:numbits
224 The number of bits in the sub prime parameter q. The default is
225 224. Only relevant if used in conjunction with the
226 dh_paramgen_type option to generate DHX parameters.
227 safeprime-generator:value
229 dh_paramgen_generator:value
230 The value to use for the generator g. The default is 2. The
231 algorithm option must be "DH" for this parameter to be used.
232 type:string
234 The type name of DH parameters to generate. Valid values are:
235 "generator"
237 Use a safe prime generator with the option safeprime_generator
238 The algorithm option must be "DH".
239 "fips186_4"
241 FIPS186-4 parameter generation. The algorithm option must be
242 "DHX".
243 "fips186_2"
245 FIPS186-4 parameter generation. The algorithm option must be
246 "DHX".
247 "group"
249 Can be used with the option pbits to select one of "ffdhe2048",
250 "ffdhe3072", "ffdhe4096", "ffdhe6144" or "ffdhe8192". The
251 algorithm option must be "DH".
252 "default"
254 Selects a default type based on the algorithm. This is used by
255 the OpenSSL default provider to set the type for backwards
256 compatability. If algorithm is "DH" then "generator" is used.
257 If algorithm is "DHX" then "fips186_2" is used.
258 dh_paramgen_type:value
260 The type of DH parameters to generate. Valid values are 0, 1, 2 or
261 3 which correspond to setting the option type to "generator",
262 "fips186_2", "fips186_4" or "group".
263 digest:digest
265 The digest to use during parameter generation. Must be one of sha1,
266 sha224 or sha256. If set, then the number of bits in qbits will
267 match the output size of the specified digest and the qbits
268 parameter will be ignored. If not set, then a digest will be used
269 that gives an output matching the number of bits in q, i.e. sha1 if
270 q length is 160, sha224 if it is 224 or sha256 if it is 256. This
271 is only used by "fips186_4" and "fips186_2" key generation.
272 properties:query
274 The digest property query string to use when fetching a digest from
275 a provider. This is only used by "fips186_4" and "fips186_2" key
276 generation.
277 gindex:index
279 The index to use for canonical generation and verification of the
280 generator g. Set this to a positive value ranging from 0..255 to
281 use this mode. Larger values will only use the bottom byte. This
282 index must then be reused during key validation to verify the value
283 of g. If this value is not set then g is not verifiable. The
284 default value is -1. This is only used by "fips186_4" and
285 "fips186_2" key generation.
286 hexseed:seed
288 The seed seed data to use instead of generating a random seed
289 internally. This should be used for testing purposes only. This
290 will either produced fixed values for the generated parameters OR
291 it will fail if the seed did not generate valid primes. This is
292 only used by "fips186_4" and "fips186_2" key generation.
293 EC Parameter Generation Options
295 The EC parameter generation options are the same as for key generation.
296 See "EC Key Generation Options" above.
297
299 The use of the genpkey program is encouraged over the algorithm
300 specific utilities because additional algorithm options and ENGINE
301 provided algorithms can be used.
302
304 Generate an RSA private key using default parameters:
305 openssl genpkey -algorithm RSA -out key.pem
307 Encrypt output private key using 128 bit AES and the passphrase
309 "hello":
310 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
312 Generate a 2048 bit RSA key using 3 as the public exponent:
314 openssl genpkey -algorithm RSA -out key.pem \
316 -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3
317 Generate 2048 bit DSA parameters that can be validated: The output
319 values for gindex and seed are required for key validation purposes and
320 are not saved to the output pem file).
321 openssl genpkey -genparam -algorithm DSA -out dsap.pem -pkeyopt pbits:2048 \
323 -pkeyopt qbits:224 -pkeyopt digest:SHA256 -pkeyopt gindex:1 -text
324 Generate DSA key from parameters:
326 openssl genpkey -paramfile dsap.pem -out dsakey.pem
328 Generate 4096 bit DH Key using safe prime group ffdhe4096:
330 openssl genpkey -algorithm DH -out dhkey.pem -pkeyopt group:ffdhe4096
332 Generate 2048 bit X9.42 DH key with 256 bit subgroup using RFC5114
334 group3:
335 openssl genpkey -algorithm DHX -out dhkey.pem -pkeyopt dh_rfc5114:3
337 Generate a DH key using a DH parameters file:
339 openssl genpkey -paramfile dhp.pem -out dhkey.pem
341 Output DH parameters for safe prime group ffdhe2048:
343 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt group:ffdhe2048
345 Output 2048 bit X9.42 DH parameters with 224 bit subgroup using RFC5114
347 group2:
348 openssl genpkey -genparam -algorithm DHX -out dhp.pem -pkeyopt dh_rfc5114:2
350 Output 2048 bit X9.42 DH parameters with 224 bit subgroup using
352 FIP186-4 keygen:
353 openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
355 -pkeyopt pbits:2048 -pkeyopt qbits:224 -pkeyopt digest:SHA256 \
356 -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:2
357 Output 1024 bit X9.42 DH parameters with 160 bit subgroup using
359 FIP186-2 keygen:
360 openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
362 -pkeyopt pbits:1024 -pkeyopt qbits:160 -pkeyopt digest:SHA1 \
363 -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:1
364 Output 2048 bit DH parameters:
366 openssl genpkey -genparam -algorithm DH -out dhp.pem \
368 -pkeyopt dh_paramgen_prime_len:2048
369 Output 2048 bit DH parameters using a generator:
371 openssl genpkey -genparam -algorithm DH -out dhpx.pem \
373 -pkeyopt dh_paramgen_prime_len:2048 \
374 -pkeyopt dh_paramgen_type:1
375 Generate EC parameters:
377 openssl genpkey -genparam -algorithm EC -out ecp.pem \
379 -pkeyopt ec_paramgen_curve:secp384r1 \
380 -pkeyopt ec_param_enc:named_curve
381 Generate EC key from parameters:
383 openssl genpkey -paramfile ecp.pem -out eckey.pem
385 Generate EC key directly:
387 openssl genpkey -algorithm EC -out eckey.pem \
389 -pkeyopt ec_paramgen_curve:P-384 \
390 -pkeyopt ec_param_enc:named_curve
391 Generate an X25519 private key:
393 openssl genpkey -algorithm X25519 -out xkey.pem
395 Generate an ED448 private key:
397 openssl genpkey -algorithm ED448 -out xkey.pem
399
401 The ability to use NIST curve names, and to generate an EC key
402 directly, were added in OpenSSL 1.0.2. The ability to generate X25519
403 keys was added in OpenSSL 1.1.0. The ability to generate X448, ED25519
404 and ED448 keys was added in OpenSSL 1.1.1.
405 The -engine option was deprecated in OpenSSL 3.0.
407
409 Copyright 2006-2021 The OpenSSL Project Authors. All Rights Reserved.
410 Licensed under the Apache License 2.0 (the "License"). You may not use
412 this file except in compliance with the License. You can obtain a copy
413 in the file LICENSE in the source distribution or at
414 <https://www.openssl.org/source/license.html>.
4153.0.9 2023-07-27 OPENSSL-GENPKEY(1ossl)