genpkey.pod revision 325337 
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<-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.
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)|openssl(1)>.
43
44=item B<-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.
62
63=item B<-pkeyopt opt:value>
64
65set the public key algorithm option B<opt> to B<value>. The precise set of
66options supported depends on the public key algorithm used and its
67implementation. See B<KEY GENERATION OPTIONS> below for more details.
68
69=item B<-genparam>
70
71generate a set of parameters instead of a private key. If used this option must
72precede and B<-algorithm>, B<-paramfile> or B<-pkeyopt> options.
73
74=item B<-paramfile filename>
75
76Some public key algorithms generate a private key based on a set of parameters.
77They can be supplied using this option. If this option is used the public key
78algorithm used is determined by the parameters. If used this option must
79precede and B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
80are mutually exclusive.
81
82=item B<-text>
83
84Print an (unencrypted) text representation of private and public keys and
85parameters along with the PEM or DER structure.
86
87=back
88
89=head1 KEY GENERATION OPTIONS
90
91The options supported by each algorith and indeed each implementation of an
92algorithm can vary. The options for the OpenSSL implementations are detailed
93below.
94
95=head1 RSA KEY GENERATION OPTIONS
96
97=over 4
98
99=item B<rsa_keygen_bits:numbits>
100
101The number of bits in the generated key. If not specified 1024 is used.
102
103=item B<rsa_keygen_pubexp:value>
104
105The RSA public exponent value. This can be a large decimal or
106hexadecimal value if preceded by B<0x>. Default value is 65537.
107
108=back
109
110=head1 DSA PARAMETER GENERATION OPTIONS
111
112=over 4
113
114=item B<dsa_paramgen_bits:numbits>
115
116The number of bits in the generated parameters. If not specified 1024 is used.
117
118=back
119
120=head1 DH PARAMETER GENERATION OPTIONS
121
122=over 4
123
124=item B<dh_paramgen_prime_len:numbits>
125
126The number of bits in the prime parameter B<p>.
127
128=item B<dh_paramgen_generator:value>
129
130The value to use for the generator B<g>.
131
132=item B<dh_rfc5114:num>
133
134If this option is set then the appropriate RFC5114 parameters are used
135instead of generating new parameters. The value B<num> can take the
136values 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of
1371024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup
138and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections
1392.1, 2.2 and 2.3 respectively.
140
141=back
142
143=head1 EC PARAMETER GENERATION OPTIONS
144
145=over 4
146
147=item B<ec_paramgen_curve:curve>
148
149the EC curve to use.
150
151=back
152
153=head1 GOST2001 KEY GENERATION AND PARAMETER OPTIONS
154
155Gost 2001 support is not enabled by default. To enable this algorithm,
156one should load the ccgost engine in the OpenSSL configuration file.
157See README.gost file in the engines/ccgost directiry of the source
158distribution for more details.
159
160Use of a parameter file for the GOST R 34.10 algorithm is optional.
161Parameters can be specified during key generation directly as well as
162during generation of parameter file.
163
164=over 4
165
166=item B<paramset:name>
167
168Specifies GOST R 34.10-2001 parameter set according to RFC 4357.
169Parameter set can be specified using abbreviated name, object short name or
170numeric OID. Following parameter sets are supported:
171
172  paramset   OID               Usage
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
179
180=back
181
182
183
184=head1 NOTES
185
186The use of the genpkey program is encouraged over the algorithm specific
187utilities because additional algorithm options and ENGINE provided algorithms
188can be used.
189
190=head1 EXAMPLES
191
192Generate an RSA private key using default parameters:
193
194 openssl genpkey -algorithm RSA -out key.pem 
195
196Encrypt output private key using 128 bit AES and the passphrase "hello":
197
198 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello
199
200Generate a 2048 bit RSA key using 3 as the public exponent:
201
202 openssl genpkey -algorithm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048 \
203 						-pkeyopt rsa_keygen_pubexp:3
204
205Generate 1024 bit DSA parameters:
206
207 openssl genpkey -genparam -algorithm DSA -out dsap.pem \
208						-pkeyopt dsa_paramgen_bits:1024
209
210Generate DSA key from parameters:
211
212 openssl genpkey -paramfile dsap.pem -out dsakey.pem 
213
214Generate 1024 bit DH parameters:
215
216 openssl genpkey -genparam -algorithm DH -out dhp.pem \
217					-pkeyopt dh_paramgen_prime_len:1024
218
219Output RFC5114 2048 bit DH parameters with 224 bit subgroup:
220
221 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt dh_rfc5114:2
222
223Generate DH key from parameters:
224
225 openssl genpkey -paramfile dhp.pem -out dhkey.pem 
226
227
228=cut
229
230