6 genpkey - generate a private key
18 [B<-pkeyopt opt:value>]
24 The B<genpkey> command generates a private key.
30 =item B<-out filename>
32 the output filename. If this argument is not specified then standard output is
35 =item B<-outform DER|PEM>
37 This specifies the output format DER or PEM.
41 the output file password source. For more information about the format of B<arg>
42 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
46 This option encrypts the private key with the supplied cipher. Any algorithm
47 name accepted by EVP_get_cipherbyname() is acceptable such as B<des3>.
51 specifying an engine (by its unique B<id> string) will cause B<genpkey>
52 to attempt to obtain a functional reference to the specified engine,
53 thus initialising it if needed. The engine will then be set as the default
54 for all available algorithms. If used this option should precede all other
57 =item B<-algorithm alg>
59 public key algorithm to use such as RSA, DSA or DH. If used this option must
60 precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
61 are mutually exclusive.
63 =item B<-pkeyopt opt:value>
65 set the public key algorithm option B<opt> to B<value>. The precise set of
66 options supported depends on the public key algorithm used and its
67 implementation. See B<KEY GENERATION OPTIONS> below for more details.
71 generate a set of parameters instead of a private key. If used this option must
72 precede and B<-algorithm>, B<-paramfile> or B<-pkeyopt> options.
74 =item B<-paramfile filename>
76 Some public key algorithms generate a private key based on a set of parameters.
77 They can be supplied using this option. If this option is used the public key
78 algorithm used is determined by the parameters. If used this option must
79 precede and B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
80 are mutually exclusive.
84 Print an (unencrypted) text representation of private and public keys and
85 parameters along with the PEM or DER structure.
89 =head1 KEY GENERATION OPTIONS
91 The options supported by each algorith and indeed each implementation of an
92 algorithm can vary. The options for the OpenSSL implementations are detailed
95 =head1 RSA KEY GENERATION OPTIONS
99 =item B<rsa_keygen_bits:numbits>
101 The number of bits in the generated key. If not specified 1024 is used.
103 =item B<rsa_keygen_pubexp:value>
105 The RSA public exponent value. This can be a large decimal or
106 hexadecimal value if preceded by B<0x>. Default value is 65537.
110 =head1 DSA PARAMETER GENERATION OPTIONS
114 =item B<dsa_paramgen_bits:numbits>
116 The number of bits in the generated parameters. If not specified 1024 is used.
120 =head1 DH PARAMETER GENERATION OPTIONS
124 =item B<dh_paramgen_prime_len:numbits>
126 The number of bits in the prime parameter B<p>.
128 =item B<dh_paramgen_generator:value>
130 The value to use for the generator B<g>.
132 =item B<dh_rfc5114:num>
134 If this option is set then the appropriate RFC5114 parameters are used
135 instead of generating new parameters. The value B<num> can take the
136 values 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of
137 1024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup
138 and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections
139 2.1, 2.2 and 2.3 respectively.
143 =head1 EC PARAMETER GENERATION OPTIONS
147 =item B<ec_paramgen_curve:curve>
153 =head1 GOST2001 KEY GENERATION AND PARAMETER OPTIONS
155 Gost 2001 support is not enabled by default. To enable this algorithm,
156 one should load the ccgost engine in the OpenSSL configuration file.
157 See README.gost file in the engines/ccgost directiry of the source
158 distribution for more details.
160 Use of a parameter file for the GOST R 34.10 algorithm is optional.
161 Parameters can be specified during key generation directly as well as
162 during generation of parameter file.
166 =item B<paramset:name>
168 Specifies GOST R 34.10-2001 parameter set according to RFC 4357.
169 Parameter set can be specified using abbreviated name, object short name or
170 numeric OID. Following parameter sets are supported:
173 A 1.2.643.2.2.35.1 Signature
174 B 1.2.643.2.2.35.2 Signature
175 C 1.2.643.2.2.35.3 Signature
176 XA 1.2.643.2.2.36.0 Key exchange
177 XB 1.2.643.2.2.36.1 Key exchange
178 test 1.2.643.2.2.35.0 Test purposes
186 The use of the genpkey program is encouraged over the algorithm specific
187 utilities because additional algorithm options and ENGINE provided algorithms
192 Generate an RSA private key using default parameters:
194 openssl genpkey -algorithm RSA -out key.pem
196 Encrypt output private key using 128 bit AES and the passphrase "hello":
198 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
200 Generate a 2048 bit RSA key using 3 as the public exponent:
202 openssl genpkey -algorithm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048 \
203 -pkeyopt rsa_keygen_pubexp:3
205 Generate 1024 bit DSA parameters:
207 openssl genpkey -genparam -algorithm DSA -out dsap.pem \
208 -pkeyopt dsa_paramgen_bits:1024
210 Generate DSA key from parameters:
212 openssl genpkey -paramfile dsap.pem -out dsakey.pem
214 Generate 1024 bit DH parameters:
216 openssl genpkey -genparam -algorithm DH -out dhp.pem \
217 -pkeyopt dh_paramgen_prime_len:1024
219 Output RFC5114 2048 bit DH parameters with 224 bit subgroup:
221 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt dh_rfc5114:2
223 Generate DH key from parameters:
225 openssl genpkey -paramfile dhp.pem -out dhkey.pem