doc/man1/openssl-genpkey.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 openssl-genpkey - generate a private key
   6
   7 =head1 SYNOPSIS
   8
   9 B<openssl> B<genpkey>
  10 [B<-help>]
  11 [B<-out filename>]
  12 [B<-outform PEM|DER>]
  13 [B<-pass arg>]
  14 [B<-I<cipher>>]
  15 [B<-engine id>]
  16 [B<-paramfile file>]
  17 [B<-algorithm alg>]
  18 [B<-pkeyopt opt:value>]
  19 [B<-genparam>]
  20 [B<-text>]
  21
  22 =head1 DESCRIPTION
  23
  24 The B<genpkey> command generates a private key.
  25
  26 =head1 OPTIONS
  27
  28 =over 4
  29
  30 =item B<-help>
  31
  32 Print out a usage message.
  33
  34 =item B<-out filename>
  35
  36 Output the key to the specified file. If this argument is not specified then
  37 standard output is used.
  38
  39 =item B<-outform DER|PEM>
  40
  41 This specifies the output format DER or PEM. The default format is PEM.
  42
  43 =item B<-pass arg>
  44
  45 The output file password source. For more information about the format of B<arg>
  46 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
  47
  48 =item B<-I<cipher>>
  49
  50 This option encrypts the private key with the supplied cipher. Any algorithm
  51 name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>.
  52
  53 =item B<-engine id>
  54
  55 Specifying an engine (by its unique B<id> string) will cause B<genpkey>
  56 to attempt to obtain a functional reference to the specified engine,
  57 thus initialising it if needed. The engine will then be set as the default
  58 for all available algorithms. If used this option should precede all other
  59 options.
  60
  61 =item B<-algorithm alg>
  62
  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
  66 built-in ones.
  67
  68 Valid built-in algorithm names for private key generation are RSA, RSA-PSS, EC,
  69 X25519, X448, ED25519 and ED448.
  70
  71 Valid built-in algorithm names for parameter generation (see the B<-genparam>
  72 option) are DH, DSA and EC.
  73
  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.
  79
  80 =item B<-pkeyopt opt:value>
  81
  82 Set the public key algorithm option B<opt> to B<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.
  86
  87 =item B<-genparam>
  88
  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.
  91
  92 =item B<-paramfile filename>
  93
  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.
  99
 100 =item B<-text>
 101
 102 Print an (unencrypted) text representation of private and public keys and
 103 parameters along with the PEM or DER structure.
 104
 105 =back
 106
 107 =head1 KEY GENERATION OPTIONS
 108
 109 The options supported by each algorithm and indeed each implementation of an
 110 algorithm can vary. The options for the OpenSSL implementations are detailed
 111 below. There are no key generation options defined for the X25519, X448, ED25519
 112 or ED448 algorithms.
 113
 114 =head2 RSA Key Generation Options
 115
 116 =over 4
 117
 118 =item B<rsa_keygen_bits:numbits>
 119
 120 The number of bits in the generated key. If not specified 2048 is used.
 121
 122 =item B<rsa_keygen_primes:numprimes>
 123
 124 The number of primes in the generated key. If not specified 2 is used.
 125
 126 =item B<rsa_keygen_pubexp:value>
 127
 128 The RSA public exponent value. This can be a large decimal or
 129 hexadecimal value if preceded by B<0x>. Default value is 65537.
 130
 131 =back
 132
 133 =head2 RSA-PSS Key Generation Options
 134
 135 Note: by default an B<RSA-PSS> key has no parameter restrictions.
 136
 137 =over 4
 138
 139 =item B<rsa_keygen_bits:numbits>, B<rsa_keygen_primes:numprimes>,  B<rsa_keygen_pubexp:value>
 140
 141 These options have the same meaning as the B<RSA> algorithm.
 142
 143 =item B<rsa_pss_keygen_md:digest>
 144
 145 If set the key is restricted and can only use B<digest> for signing.
 146
 147 =item B<rsa_pss_keygen_mgf1_md:digest>
 148
 149 If set the key is restricted and can only use B<digest> as it's MGF1
 150 parameter.
 151
 152 =item B<rsa_pss_keygen_saltlen:len>
 153
 154 If set the key is restricted and B<len> specifies the minimum salt length.
 155
 156 =back
 157
 158 =head2 EC Key Generation Options
 159
 160 The EC key generation options can also be used for parameter generation.
 161
 162 =over 4
 163
 164 =item B<ec_paramgen_curve:curve>
 165
 166 The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
 167
 168 =item B<ec_param_enc:encoding>
 169
 170 The encoding to use for parameters. The "encoding" parameter must be either
 171 "named_curve" or "explicit". The default value is "named_curve".
 172
 173 =back
 174
 175 =head1 PARAMETER GENERATION OPTIONS
 176
 177 The options supported by each algorithm and indeed each implementation of an
 178 algorithm can vary. The options for the OpenSSL implementations are detailed
 179 below.
 180
 181 =head2 DSA Parameter Generation Options
 182
 183 =over 4
 184
 185 =item B<dsa_paramgen_bits:numbits>
 186
 187 The number of bits in the generated prime. If not specified 2048 is used.
 188
 189 =item B<dsa_paramgen_q_bits:numbits>
 190
 191 The number of bits in the q parameter. Must be one of 160, 224 or 256. If not
 192 specified 224 is used.
 193
 194 =item B<dsa_paramgen_md:digest>
 195
 196 The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
 197 or B<sha256>. If set, then the number of bits in B<q> will match the output size
 198 of the specified digest and the B<dsa_paramgen_q_bits> parameter will be
 199 ignored. If not set, then a digest will be used that gives an output matching
 200 the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it 224
 201 or B<sha256> if it is 256.
 202
 203 =back
 204
 205 =head2 DH Parameter Generation Options
 206
 207 =over 4
 208
 209 =item B<dh_paramgen_prime_len:numbits>
 210
 211 The number of bits in the prime parameter B<p>. The default is 2048.
 212
 213 =item B<dh_paramgen_subprime_len:numbits>
 214
 215 The number of bits in the sub prime parameter B<q>. The default is 256 if the
 216 prime is at least 2048 bits long or 160 otherwise. Only relevant if used in
 217 conjunction with the B<dh_paramgen_type> option to generate X9.42 DH parameters.
 218
 219 =item B<dh_paramgen_generator:value>
 220
 221 The value to use for the generator B<g>. The default is 2.
 222
 223 =item B<dh_paramgen_type:value>
 224
 225 The type of DH parameters to generate. Use 0 for PKCS#3 DH and 1 for X9.42 DH.
 226 The default is 0.
 227
 228 =item B<dh_rfc5114:num>
 229
 230 If this option is set, then the appropriate RFC5114 parameters are used
 231 instead of generating new parameters. The value B<num> can take the
 232 values 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of
 233 1024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup
 234 and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections
 235 2.1, 2.2 and 2.3 respectively. If present this overrides all other DH parameter
 236 options.
 237
 238 =back
 239
 240 =head2 EC Parameter Generation Options
 241
 242 The EC parameter generation options are the same as for key generation. See
 243 L<EC Key Generation Options> above.
 244
 245 =head1 NOTES
 246
 247 The use of the genpkey program is encouraged over the algorithm specific
 248 utilities because additional algorithm options and ENGINE provided algorithms
 249 can be used.
 250
 251 =head1 EXAMPLES
 252
 253 Generate an RSA private key using default parameters:
 254
 255  openssl genpkey -algorithm RSA -out key.pem
 256
 257 Encrypt output private key using 128 bit AES and the passphrase "hello":
 258
 259  openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
 260
 261 Generate a 2048 bit RSA key using 3 as the public exponent:
 262
 263  openssl genpkey -algorithm RSA -out key.pem \
 264      -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3
 265
 266 Generate 2048 bit DSA parameters:
 267
 268  openssl genpkey -genparam -algorithm DSA -out dsap.pem \
 269      -pkeyopt dsa_paramgen_bits:2048
 270
 271 Generate DSA key from parameters:
 272
 273  openssl genpkey -paramfile dsap.pem -out dsakey.pem
 274
 275 Generate 2048 bit DH parameters:
 276
 277  openssl genpkey -genparam -algorithm DH -out dhp.pem \
 278      -pkeyopt dh_paramgen_prime_len:2048
 279
 280 Generate 2048 bit X9.42 DH parameters:
 281
 282  openssl genpkey -genparam -algorithm DH -out dhpx.pem \
 283      -pkeyopt dh_paramgen_prime_len:2048 \
 284      -pkeyopt dh_paramgen_type:1
 285
 286 Output RFC5114 2048 bit DH parameters with 224 bit subgroup:
 287
 288  openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt dh_rfc5114:2
 289
 290 Generate DH key from parameters:
 291
 292  openssl genpkey -paramfile dhp.pem -out dhkey.pem
 293
 294 Generate EC parameters:
 295
 296  openssl genpkey -genparam -algorithm EC -out ecp.pem \
 297         -pkeyopt ec_paramgen_curve:secp384r1 \
 298         -pkeyopt ec_param_enc:named_curve
 299
 300 Generate EC key from parameters:
 301
 302  openssl genpkey -paramfile ecp.pem -out eckey.pem
 303
 304 Generate EC key directly:
 305
 306  openssl genpkey -algorithm EC -out eckey.pem \
 307         -pkeyopt ec_paramgen_curve:P-384 \
 308         -pkeyopt ec_param_enc:named_curve
 309
 310 Generate an X25519 private key:
 311
 312  openssl genpkey -algorithm X25519 -out xkey.pem
 313
 314 Generate an ED448 private key:
 315
 316  openssl genpkey -algorithm ED448 -out xkey.pem
 317
 318 =head1 HISTORY
 319
 320 The ability to use NIST curve names, and to generate an EC key directly,
 321 were added in OpenSSL 1.0.2.
 322 The ability to generate X25519 keys was added in OpenSSL 1.1.0.
 323 The ability to generate X448, ED25519 and ED448 keys was added in OpenSSL 1.1.1.
 324
 325 =head1 COPYRIGHT
 326
 327 Copyright 2006-2019 The OpenSSL Project Authors. All Rights Reserved.
 328
 329 Licensed under the Apache License 2.0 (the "License").  You may not use
 330 this file except in compliance with the License.  You can obtain a copy
 331 in the file LICENSE in the source distribution or at
 332 L<https://www.openssl.org/source/license.html>.
 333
 334 =cut