4 {- join("\n", @autowarntext) -}
10 openssl-genpkey - generate a private key
17 [B<-outform> B<DER>|B<PEM>]
20 [B<-paramfile> I<file>]
21 [B<-algorithm> I<alg>]
22 [B<-pkeyopt> I<opt>:I<value>]
25 {- $OpenSSL::safe::opt_engine_synopsis -}
27 =for openssl ifdef engine
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; the default is B<PEM>.
49 See L<openssl(1)/Format Options> for details.
53 The output file password source. For more information about the format of I<arg>
54 see L<openssl(1)/Pass Phrase Options>.
58 This option encrypts the private key with the supplied cipher. Any algorithm
59 name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>.
61 =item B<-algorithm> I<alg>
63 Public key algorithm to use such as RSA, DSA or DH. If used this option must
64 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
65 are mutually exclusive. Engines may add algorithms in addition to the standard
68 Valid built-in algorithm names for private key generation are RSA, RSA-PSS, EC,
69 X25519, X448, ED25519 and ED448.
71 Valid built-in algorithm names for parameter generation (see the B<-genparam>
72 option) are DH, DSA and EC.
74 Note that the algorithm name X9.42 DH may be used as a synonym for the DH
75 algorithm. These are identical and do not indicate the type of parameters that
76 will be generated. Use the B<dh_paramgen_type> option to indicate whether PKCS#3
77 or X9.42 DH parameters are required. See L</DH Parameter Generation Options>
78 below for more details.
80 =item B<-pkeyopt> I<opt>:I<value>
82 Set the public key algorithm option I<opt> to I<value>. The precise set of
83 options supported depends on the public key algorithm used and its
84 implementation. See L</KEY GENERATION OPTIONS> and
85 L</PARAMETER GENERATION OPTIONS> below for more details.
89 Generate a set of parameters instead of a private key. If used this option must
90 precede any B<-algorithm>, B<-paramfile> or B<-pkeyopt> options.
92 =item B<-paramfile> I<filename>
94 Some public key algorithms generate a private key based on a set of parameters.
95 They can be supplied using this option. If this option is used the public key
96 algorithm used is determined by the parameters. If used this option must
97 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
98 are mutually exclusive.
102 Print an (unencrypted) text representation of private and public keys and
103 parameters along with the PEM or DER structure.
105 {- $OpenSSL::safe::opt_engine_item -}
109 =head1 KEY GENERATION OPTIONS
111 The options supported by each algorithm and indeed each implementation of an
112 algorithm can vary. The options for the OpenSSL implementations are detailed
113 below. There are no key generation options defined for the X25519, X448, ED25519
116 =head2 RSA Key Generation Options
120 =item B<rsa_keygen_bits:numbits>
122 The number of bits in the generated key. If not specified 2048 is used.
124 =item B<rsa_keygen_primes:numprimes>
126 The number of primes in the generated key. If not specified 2 is used.
128 =item B<rsa_keygen_pubexp:value>
130 The RSA public exponent value. This can be a large decimal or
131 hexadecimal value if preceded by C<0x>. Default value is 65537.
135 =head2 RSA-PSS Key Generation Options
137 Note: by default an B<RSA-PSS> key has no parameter restrictions.
141 =item B<rsa_keygen_bits>:I<numbits>, B<rsa_keygen_primes>:I<numprimes>,
142 B<rsa_keygen_pubexp>:I<value>
144 These options have the same meaning as the B<RSA> algorithm.
146 =item B<rsa_pss_keygen_md>:I<digest>
148 If set the key is restricted and can only use I<digest> for signing.
150 =item B<rsa_pss_keygen_mgf1_md>:I<digest>
152 If set the key is restricted and can only use I<digest> as it's MGF1
155 =item B<rsa_pss_keygen_saltlen>:I<len>
157 If set the key is restricted and I<len> specifies the minimum salt length.
161 =head2 EC Key Generation Options
163 The EC key generation options can also be used for parameter generation.
167 =item B<ec_paramgen_curve>:I<curve>
169 The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
171 =item B<ec_param_enc>:I<encoding>
173 The encoding to use for parameters. The I<encoding> parameter must be either
174 B<named_curve> or B<explicit>. The default value is B<named_curve>.
178 =head1 PARAMETER GENERATION OPTIONS
180 The options supported by each algorithm and indeed each implementation of an
181 algorithm can vary. The options for the OpenSSL implementations are detailed
184 =head2 DSA Parameter Generation Options
188 =item B<dsa_paramgen_bits>:I<numbits>
190 The number of bits in the generated prime. If not specified 2048 is used.
192 =item B<dsa_paramgen_q_bits>:I<numbits>
194 The number of bits in the q parameter. Must be one of 160, 224 or 256. If not
195 specified 224 is used.
197 =item B<dsa_paramgen_md>:I<digest>
199 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
200 or B<sha256>. If set, then the number of bits in B<q> will match the output size
201 of the specified digest and the B<dsa_paramgen_q_bits> parameter will be
202 ignored. If not set, then a digest will be used that gives an output matching
203 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it 224
204 or B<sha256> if it is 256.
208 =head2 DH Parameter Generation Options
212 =item B<dh_paramgen_prime_len>:I<numbits>
214 The number of bits in the prime parameter I<p>. The default is 2048.
216 =item B<dh_paramgen_subprime_len>:I<numbits>
218 The number of bits in the sub prime parameter I<q>. The default is 256 if the
219 prime is at least 2048 bits long or 160 otherwise. Only relevant if used in
220 conjunction with the B<dh_paramgen_type> option to generate X9.42 DH parameters.
222 =item B<dh_paramgen_generator>:I<value>
224 The value to use for the generator I<g>. The default is 2.
226 =item B<dh_paramgen_type>:I<value>
228 The type of DH parameters to generate. Use 0 for PKCS#3 DH and 1 for X9.42 DH.
231 =item B<dh_rfc5114>:I<num>
233 If this option is set, then the appropriate RFC5114 parameters are used
234 instead of generating new parameters. The value I<num> can be one of
235 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of
236 1024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup
237 and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections
238 2.1, 2.2 and 2.3 respectively. If present this overrides all other DH parameter
243 =head2 EC Parameter Generation Options
245 The EC parameter generation options are the same as for key generation. See
246 L</EC Key Generation Options> above.
250 The use of the genpkey program is encouraged over the algorithm specific
251 utilities because additional algorithm options and ENGINE provided algorithms
256 Generate an RSA private key using default parameters:
258 openssl genpkey -algorithm RSA -out key.pem
260 Encrypt output private key using 128 bit AES and the passphrase "hello":
262 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
264 Generate a 2048 bit RSA key using 3 as the public exponent:
266 openssl genpkey -algorithm RSA -out key.pem \
267 -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3
269 Generate 2048 bit DSA parameters:
271 openssl genpkey -genparam -algorithm DSA -out dsap.pem \
272 -pkeyopt dsa_paramgen_bits:2048
274 Generate DSA key from parameters:
276 openssl genpkey -paramfile dsap.pem -out dsakey.pem
278 Generate 2048 bit DH parameters:
280 openssl genpkey -genparam -algorithm DH -out dhp.pem \
281 -pkeyopt dh_paramgen_prime_len:2048
283 Generate 2048 bit X9.42 DH parameters:
285 openssl genpkey -genparam -algorithm DH -out dhpx.pem \
286 -pkeyopt dh_paramgen_prime_len:2048 \
287 -pkeyopt dh_paramgen_type:1
289 Output RFC5114 2048 bit DH parameters with 224 bit subgroup:
291 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt dh_rfc5114:2
293 Generate DH key from parameters:
295 openssl genpkey -paramfile dhp.pem -out dhkey.pem
297 Generate EC parameters:
299 openssl genpkey -genparam -algorithm EC -out ecp.pem \
300 -pkeyopt ec_paramgen_curve:secp384r1 \
301 -pkeyopt ec_param_enc:named_curve
303 Generate EC key from parameters:
305 openssl genpkey -paramfile ecp.pem -out eckey.pem
307 Generate EC key directly:
309 openssl genpkey -algorithm EC -out eckey.pem \
310 -pkeyopt ec_paramgen_curve:P-384 \
311 -pkeyopt ec_param_enc:named_curve
313 Generate an X25519 private key:
315 openssl genpkey -algorithm X25519 -out xkey.pem
317 Generate an ED448 private key:
319 openssl genpkey -algorithm ED448 -out xkey.pem
323 The ability to use NIST curve names, and to generate an EC key directly,
324 were added in OpenSSL 1.0.2.
325 The ability to generate X25519 keys was added in OpenSSL 1.1.0.
326 The ability to generate X448, ED25519 and ED448 keys was added in OpenSSL 1.1.1.
330 Copyright 2006-2019 The OpenSSL Project Authors. All Rights Reserved.
332 Licensed under the Apache License 2.0 (the "License"). You may not use
333 this file except in compliance with the License. You can obtain a copy
334 in the file LICENSE in the source distribution or at
335 L<https://www.openssl.org/source/license.html>.