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)|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 it's unique B<id> string) will cause B<req>
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 algorith 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.
117 =head1 DH PARAMETER GENERATION OPTIONS
121 =item B<dh_paramgen_prime_len:numbits>
123 The number of bits in the prime parameter B<p>.
125 =item B<dh_paramgen_generator:value>
127 The value to use for the generator B<g>.
131 =head1 EC PARAMETER GENERATION OPTIONS
135 =item B<ec_paramgen_curve:curve>
143 The use of the genpkey program is encouraged over the algorithm specific
144 utilities because additional algorithm options and ENGINE provided algorithms
149 Generate an RSA private key using default parameters:
151 openssl genpkey -algoritm RSA -out key.pem
153 Encrypt output private key using 128 bit AES and the passphrase "hello":
155 openssl genpkey -algoritm RSA -out key.pem -aes-128-cbc -pass pass:hello
157 Generate a 2048 bit RSA key using 3 as the public exponent:
159 openssl genpkey -algoritm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048 \
160 -pkeyopt rsa_keygen_pubexp:3
162 Generate 1024 bit DSA parameters:
164 openssl genpkey -genparam -algorithm DSA -out dsap.pem \
165 -pkeyopt dsa_paramgen_bits:1024
167 Generate DSA key from parameters:
169 openssl genpkey -paramfile dsap.pem -out dsakey.pem
171 Generate 1024 bit DH parameters:
173 openssl genpkey -genparam -algorithm DH -out dhp.pem \
174 -pkeyopt dh_paramgen_prime_len:1024
176 Generate DH key from parameters:
178 openssl genpkey -paramfile dhp.pem -out dhkey.pem