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 These options encrypt 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.
55 =item B<-algorithm alg>
57 public key algorithm to use such as RSA, DSA or DH.
59 =item B<-pkeyopt opt:value>
61 set the public key algorithm option B<opt> to B<value>. The precise set of
62 options supported depends on the public key algorithm used and its
63 implementation. See B<KEY GENERATION OPTIONS> below for more details.
67 generate a set of parameters instead of a private key.
69 =item B<-paramfile filename>
71 Some public key algorithms generate a private key based on a set of parameters.
72 They can be supplied using this option. If this option is used the public
73 key algorithm used is determined by the parameters.
77 =head1 KEY GENERATION OPTIONS
79 The options supported by each algorith and indeed each implementation of an
80 algorithm can vary. The options for the OpenSSL implementations are detailed
83 =head1 RSA KEY GENERATION OPTIONS
87 =item B<rsa_keygen_bits:numbits>
89 The number of bits in the generated key. If not specified 1024 is used.
91 =item B<rsa_keygen_pubexp:value>
93 The RSA public exponent value. This can be a large decimal or
94 hexadecimal value if preceded by B<0x>. Default value is 65537.
98 =head1 DSA PARAMETER GENERATION OPTIONS
102 =item B<dsa_paramgen_bits:numbits>
104 The number of bits in the generated parameters. If not specified 1024 is used.
106 =head1 DH PARAMETER GENERATION OPTIONS
110 =item B<dh_paramgen_prime_len:numbits>
112 The number of bits in the prime parameter B<p>.
114 =item B<dh_paramgen_generator:value>
116 The value to use for the generator B<g>.
120 =head1 EC PARAMETER GENERATION OPTIONS
124 =item B<ec_paramgen_curve:curve>
132 The use of the genpkey program is encouraged over the algorithm specific
133 utilities because additional algorithm options and ENGINE provided algorithms
138 Generate an RSA private key using default parameters:
140 openssl genpkey -algoritm RSA -out key.pem
142 Encrypt output private key using 128 bit AES and the passphrase "hello":
144 openssl genpkey -algoritm RSA -out key.pem -aes-128-cbc -pass pass:hello
146 Generate a 2048 bit RSA key using 3 as the public exponent:
148 openssl genpkey -algoritm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048 \
149 -pkeyopt rsa_keygen_pubexp:3
151 Generate 1024 bit DSA parameters:
153 openssl genpkey -genparam -algorithm DSA -out dsap.pem \
154 -pkeyopt dsa_paramgen_bits:1024
156 Generate DSA key from parameters:
158 openssl genpkey -paramfile dsap.pem -out dsakey.pem
160 Generate 1024 bit DH parameters:
162 openssl genpkey -genparam -algorithm DH -out dhp.pem \
163 -pkeyopt dh_paramgen_prime_len:1024
165 Generate DH key from parameters:
167 openssl genpkey -paramfile dhp.pem -out dhkey.pem