5 genpkey - generate a private key
17 [B<-pkeyopt opt:value>]
23 The B<genpkey> command generates a private key.
29 =item B<-out filename>
31 the output filename. If this argument is not specified then standard output is
34 =item B<-outform DER|PEM>
36 This specifies the output format DER or PEM.
40 the output file password source. For more information about the format of B<arg>
41 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
45 This option encrypts the private key with the supplied cipher. Any algorithm
46 name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>.
50 specifying an engine (by its unique B<id> string) will cause B<genpkey>
51 to attempt to obtain a functional reference to the specified engine,
52 thus initialising it if needed. The engine will then be set as the default
53 for all available algorithms. If used this option should precede all other
56 =item B<-algorithm alg>
58 public key algorithm to use such as RSA, DSA or DH. If used this option must
59 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
60 are mutually exclusive.
62 =item B<-pkeyopt opt:value>
64 set the public key algorithm option B<opt> to B<value>. The precise set of
65 options supported depends on the public key algorithm used and its
66 implementation. See B<KEY GENERATION OPTIONS> below for more details.
70 generate a set of parameters instead of a private key. If used this option must
71 precede and B<-algorithm>, B<-paramfile> or B<-pkeyopt> options.
73 =item B<-paramfile filename>
75 Some public key algorithms generate a private key based on a set of parameters.
76 They can be supplied using this option. If this option is used the public key
77 algorithm used is determined by the parameters. If used this option must
78 precede and B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
79 are mutually exclusive.
83 Print an (unencrypted) text representation of private and public keys and
84 parameters along with the PEM or DER structure.
88 =head1 KEY GENERATION OPTIONS
90 The options supported by each algorithm and indeed each implementation of an
91 algorithm can vary. The options for the OpenSSL implementations are detailed
94 =head1 RSA KEY GENERATION OPTIONS
98 =item B<rsa_keygen_bits:numbits>
100 The number of bits in the generated key. If not specified 1024 is used.
102 =item B<rsa_keygen_pubexp:value>
104 The RSA public exponent value. This can be a large decimal or
105 hexadecimal value if preceded by B<0x>. Default value is 65537.
109 =head1 DSA PARAMETER GENERATION OPTIONS
113 =item B<dsa_paramgen_bits:numbits>
115 The number of bits in the generated parameters. If not specified 1024 is used.
119 =head1 DH PARAMETER GENERATION OPTIONS
123 =item B<dh_paramgen_prime_len:numbits>
125 The number of bits in the prime parameter B<p>.
127 =item B<dh_paramgen_generator:value>
129 The value to use for the generator B<g>.
131 =item B<dh_rfc5114:num>
133 If this option is set then the appropriate RFC5114 parameters are used
134 instead of generating new parameters. The value B<num> can take the
135 values 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of
136 1024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup
137 and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections
138 2.1, 2.2 and 2.3 respectively.
142 =head1 EC PARAMETER GENERATION OPTIONS
144 The EC parameter generation options below can also
145 be supplied as EC key generation options. This can (for example) generate a
146 key from a named curve without the need to use an explicit parameter file.
150 =item B<ec_paramgen_curve:curve>
152 the EC curve to use. OpenSSL supports NIST curve names such as "P-256".
154 =item B<ec_param_enc:encoding>
156 the encoding to use for parameters. The "encoding" parameter must be either
157 "named_curve" or "explicit".
161 =head1 GOST2001 KEY GENERATION AND PARAMETER OPTIONS
163 Gost 2001 support is not enabled by default. To enable this algorithm,
164 one should load the ccgost engine in the OpenSSL configuration file.
165 See README.gost file in the engines/ccgost directory of the source
166 distribution for more details.
168 Use of a parameter file for the GOST R 34.10 algorithm is optional.
169 Parameters can be specified during key generation directly as well as
170 during generation of parameter file.
174 =item B<paramset:name>
176 Specifies GOST R 34.10-2001 parameter set according to RFC 4357.
177 Parameter set can be specified using abbreviated name, object short name or
178 numeric OID. Following parameter sets are supported:
181 A 1.2.643.2.2.35.1 Signature
182 B 1.2.643.2.2.35.2 Signature
183 C 1.2.643.2.2.35.3 Signature
184 XA 1.2.643.2.2.36.0 Key exchange
185 XB 1.2.643.2.2.36.1 Key exchange
186 test 1.2.643.2.2.35.0 Test purposes
194 The use of the genpkey program is encouraged over the algorithm specific
195 utilities because additional algorithm options and ENGINE provided algorithms
200 Generate an RSA private key using default parameters:
202 openssl genpkey -algorithm RSA -out key.pem
204 Encrypt output private key using 128 bit AES and the passphrase "hello":
206 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
208 Generate a 2048 bit RSA key using 3 as the public exponent:
210 openssl genpkey -algorithm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048 \
211 -pkeyopt rsa_keygen_pubexp:3
213 Generate 1024 bit DSA parameters:
215 openssl genpkey -genparam -algorithm DSA -out dsap.pem \
216 -pkeyopt dsa_paramgen_bits:1024
218 Generate DSA key from parameters:
220 openssl genpkey -paramfile dsap.pem -out dsakey.pem
222 Generate 1024 bit DH parameters:
224 openssl genpkey -genparam -algorithm DH -out dhp.pem \
225 -pkeyopt dh_paramgen_prime_len:1024
227 Output RFC5114 2048 bit DH parameters with 224 bit subgroup:
229 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt dh_rfc5114:2
231 Generate DH key from parameters:
233 openssl genpkey -paramfile dhp.pem -out dhkey.pem
235 Generate EC parameters:
237 openssl genpkey -genparam -algorithm EC -out ecp.pem \
238 -pkeyopt ec_paramgen_curve:secp384r1 \
239 -pkeyopt ec_param_enc:named_curve
241 Generate EC key from parameters:
243 openssl genpkey -paramfile ecp.pem -out eckey.pem
245 Generate EC key directly:
247 openssl genpkey -algorithm EC -out eckey.pem \
248 -pkeyopt ec_paramgen_curve:P-384 \
249 -pkeyopt ec_param_enc:named_curve
253 The ability to use NIST curve names, and to generate an EC key directly,
254 were added in OpenSSL 1.0.2.