genpkey.pod revision 337982
1=pod 2 3=head1 NAME 4 5openssl-genpkey, 6genpkey - generate a private key 7 8=head1 SYNOPSIS 9 10B<openssl> B<genpkey> 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 24The B<genpkey> command generates a private key. 25 26=head1 OPTIONS 27 28=over 4 29 30=item B<-out filename> 31 32the output filename. If this argument is not specified then standard output is 33used. 34 35=item B<-outform DER|PEM> 36 37This specifies the output format DER or PEM. The default format is PEM. 38 39=item B<-pass arg> 40 41The output file password source. For more information about the format of B<arg> 42see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>. 43 44=item B<-I<cipher>> 45 46This option encrypts the private key with the supplied cipher. Any algorithm 47name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>. 48 49=item B<-engine id> 50 51Specifying an engine (by its unique B<id> string) will cause B<genpkey> 52to attempt to obtain a functional reference to the specified engine, 53thus initialising it if needed. The engine will then be set as the default 54for all available algorithms. If used this option should precede all other 55options. 56 57=item B<-algorithm alg> 58 59Public key algorithm to use such as RSA, DSA or DH. If used this option must 60precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm> 61are mutually exclusive. Engines may add algorithms in addition to the standard 62built-in ones. 63 64Valid built-in algorithm names for private key generation are RSA and EC. 65 66Valid built-in algorithm names for parameter generation (see the B<-genparam> 67option) are DH, DSA and EC. 68 69Note that the algorithm name X9.42 DH may be used as a synonym for the DH 70algorithm. These are identical and do not indicate the type of parameters that 71will be generated. Use the B<dh_paramgen_type> option to indicate whether PKCS#3 72or X9.42 DH parameters are required. See L<DH Parameter Generation Options> 73below for more details. 74 75=item B<-pkeyopt opt:value> 76 77Set the public key algorithm option B<opt> to B<value>. The precise set of 78options supported depends on the public key algorithm used and its 79implementation. See L<KEY GENERATION OPTIONS> and 80L<PARAMETER GENERATION OPTIONS> below for more details. 81 82=item B<-genparam> 83 84Generate a set of parameters instead of a private key. If used this option must 85precede any B<-algorithm>, B<-paramfile> or B<-pkeyopt> options. 86 87=item B<-paramfile filename> 88 89Some public key algorithms generate a private key based on a set of parameters. 90They can be supplied using this option. If this option is used the public key 91algorithm used is determined by the parameters. If used this option must 92precede and B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm> 93are mutually exclusive. 94 95=item B<-text> 96 97Print an (unencrypted) text representation of private and public keys and 98parameters along with the PEM or DER structure. 99 100=back 101 102=head1 KEY GENERATION OPTIONS 103 104The options supported by each algorith and indeed each implementation of an 105algorithm can vary. The options for the OpenSSL implementations are detailed 106below. 107 108=head2 RSA Key Generation Options 109 110=over 4 111 112=item B<rsa_keygen_bits:numbits> 113 114The number of bits in the generated key. If not specified 1024 is used. 115 116=item B<rsa_keygen_pubexp:value> 117 118The RSA public exponent value. This can be a large decimal or 119hexadecimal value if preceded by B<0x>. Default value is 65537. 120 121=back 122 123=head2 EC Key Generation Options 124 125The EC key generation options can also be used for parameter generation. 126 127=over 4 128 129=item B<ec_paramgen_curve:curve> 130 131The EC curve to use. OpenSSL supports NIST curve names such as "P-256". 132 133=item B<ec_param_enc:encoding> 134 135The encoding to use for parameters. The "encoding" parameter must be either 136"named_curve" or "explicit". The default value is "named_curve". 137 138=back 139 140=head1 PARAMETER GENERATION OPTIONS 141 142The options supported by each algorithm and indeed each implementation of an 143algorithm can vary. The options for the OpenSSL implementations are detailed 144below. 145 146=head2 DSA Parameter Generation Options 147 148=over 4 149 150=item B<dsa_paramgen_bits:numbits> 151 152The number of bits in the generated prime. If not specified 1024 is used. 153 154=item B<dsa_paramgen_q_bits:numbits> 155 156The number of bits in the q parameter. Must be one of 160, 224 or 256. If not 157specified 160 is used. 158 159=item B<dsa_paramgen_md:digest> 160 161The digest to use during parameter generation. Must be one of B<sha1>, B<sha224> 162or B<sha256>. If set, then the number of bits in B<q> will match the output size 163of the specified digest and the B<dsa_paramgen_q_bits> parameter will be 164ignored. If not set, then a digest will be used that gives an output matching 165the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it 224 166or B<sha256> if it is 256. 167 168=back 169 170=head2 DH Parameter Generation Options 171 172=over 4 173 174=item B<dh_paramgen_prime_len:numbits> 175 176The number of bits in the prime parameter B<p>. The default is 1024. 177 178=item B<dh_paramgen_subprime_len:numbits> 179 180The number of bits in the sub prime parameter B<q>. The default is 256 if the 181prime is at least 2048 bits long or 160 otherwise. Only relevant if used in 182conjunction with the B<dh_paramgen_type> option to generate X9.42 DH parameters. 183 184=item B<dh_paramgen_generator:value> 185 186The value to use for the generator B<g>. The default is 2. 187 188=item B<dh_paramgen_type:value> 189 190The type of DH parameters to generate. Use 0 for PKCS#3 DH and 1 for X9.42 DH. 191The default is 0. 192 193=item B<dh_rfc5114:num> 194 195If this option is set, then the appropriate RFC5114 parameters are used 196instead of generating new parameters. The value B<num> can take the 197values 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of 1981024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup 199and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections 2002.1, 2.2 and 2.3 respectively. If present this overrides all other DH parameter 201options. 202 203=back 204 205=head2 EC Parameter Generation Options 206 207The EC parameter generation options are the same as for key generation. See 208L<EC Key Generation Options> above. 209 210=head1 GOST2001 KEY GENERATION AND PARAMETER OPTIONS 211 212Gost 2001 support is not enabled by default. To enable this algorithm, 213one should load the ccgost engine in the OpenSSL configuration file. 214See README.gost file in the engines/ccgost directiry of the source 215distribution for more details. 216 217Use of a parameter file for the GOST R 34.10 algorithm is optional. 218Parameters can be specified during key generation directly as well as 219during generation of parameter file. 220 221=over 4 222 223=item B<paramset:name> 224 225Specifies GOST R 34.10-2001 parameter set according to RFC 4357. 226Parameter set can be specified using abbreviated name, object short name or 227numeric OID. Following parameter sets are supported: 228 229 paramset OID Usage 230 A 1.2.643.2.2.35.1 Signature 231 B 1.2.643.2.2.35.2 Signature 232 C 1.2.643.2.2.35.3 Signature 233 XA 1.2.643.2.2.36.0 Key exchange 234 XB 1.2.643.2.2.36.1 Key exchange 235 test 1.2.643.2.2.35.0 Test purposes 236 237=back 238 239=head1 NOTES 240 241The use of the genpkey program is encouraged over the algorithm specific 242utilities because additional algorithm options and ENGINE provided algorithms 243can be used. 244 245=head1 EXAMPLES 246 247Generate an RSA private key using default parameters: 248 249 openssl genpkey -algorithm RSA -out key.pem 250 251Encrypt output private key using 128 bit AES and the passphrase "hello": 252 253 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello 254 255Generate a 2048 bit RSA key using 3 as the public exponent: 256 257 openssl genpkey -algorithm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048 \ 258 -pkeyopt rsa_keygen_pubexp:3 259 260Generate 2048 bit DSA parameters: 261 262 openssl genpkey -genparam -algorithm DSA -out dsap.pem \ 263 -pkeyopt dsa_paramgen_bits:2048 264 265Generate DSA key from parameters: 266 267 openssl genpkey -paramfile dsap.pem -out dsakey.pem 268 269Generate 2048 bit DH parameters: 270 271 openssl genpkey -genparam -algorithm DH -out dhp.pem \ 272 -pkeyopt dh_paramgen_prime_len:2048 273 274Generate 2048 bit X9.42 DH parameters: 275 276 openssl genpkey -genparam -algorithm DH -out dhpx.pem \ 277 -pkeyopt dh_paramgen_prime_len:2048 \ 278 -pkeyopt dh_paramgen_type:1 279 280Output RFC5114 2048 bit DH parameters with 224 bit subgroup: 281 282 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt dh_rfc5114:2 283 284Generate DH key from parameters: 285 286 openssl genpkey -paramfile dhp.pem -out dhkey.pem 287 288Generate EC key directly: 289 290 openssl genpkey -algorithm EC -out eckey.pem \ 291 -pkeyopt ec_paramgen_curve:P-384 \ 292 -pkeyopt ec_param_enc:named_curve 293 294=head1 HISTORY 295 296The ability to use NIST curve names, and to generate an EC key directly, 297were added in OpenSSL 1.0.2. 298 299=cut 300 301