genrsa.pod revision 325335 
1=pod
2
3=head1 NAME
4
5genrsa - generate an RSA private key
6
7=head1 SYNOPSIS
8
9B<openssl> B<genrsa>
10[B<-help>]
11[B<-out filename>]
12[B<-passout arg>]
13[B<-aes128>]
14[B<-aes192>]
15[B<-aes256>]
16[B<-aria128>]
17[B<-aria192>]
18[B<-aria256>]
19[B<-camellia128>]
20[B<-camellia192>]
21[B<-camellia256>]
22[B<-des>]
23[B<-des3>]
24[B<-idea>]
25[B<-f4>]
26[B<-3>]
27[B<-rand file(s)>]
28[B<-engine id>]
29[B<numbits>]
30
31=head1 DESCRIPTION
32
33The B<genrsa> command generates an RSA private key.
34
35=head1 OPTIONS
36
37=over 4
38
39=item B<-help>
40
41Print out a usage message.
42
43=item B<-out filename>
44
45Output the key to the specified file. If this argument is not specified then
46standard output is used.
47
48=item B<-passout arg>
49
50the output file password source. For more information about the format of B<arg>
51see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
52
53=item B<-aes128|-aes192|-aes256|-aria128|-aria192|-aria256|-camellia128|-camellia192|-camellia256|-des|-des3|-idea>
54
55These options encrypt the private key with specified
56cipher before outputting it. If none of these options is
57specified no encryption is used. If encryption is used a pass phrase is prompted
58for if it is not supplied via the B<-passout> argument.
59
60=item B<-F4|-3>
61
62the public exponent to use, either 65537 or 3. The default is 65537.
63
64=item B<-rand file(s)>
65
66a file or files containing random data used to seed the random number
67generator, or an EGD socket (see L<RAND_egd(3)>).
68Multiple files can be specified separated by an OS-dependent character.
69The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
70all others.
71
72=item B<-engine id>
73
74specifying an engine (by its unique B<id> string) will cause B<genrsa>
75to attempt to obtain a functional reference to the specified engine,
76thus initialising it if needed. The engine will then be set as the default
77for all available algorithms.
78
79=item B<numbits>
80
81the size of the private key to generate in bits. This must be the last option
82specified. The default is 2048.
83
84=back
85
86=head1 NOTES
87
88RSA private key generation essentially involves the generation of two prime
89numbers. When generating a private key various symbols will be output to
90indicate the progress of the generation. A B<.> represents each number which
91has passed an initial sieve test, B<+> means a number has passed a single
92round of the Miller-Rabin primality test. A newline means that the number has
93passed all the prime tests (the actual number depends on the key size).
94
95Because key generation is a random process the time taken to generate a key
96may vary somewhat.
97
98=head1 BUGS
99
100A quirk of the prime generation algorithm is that it cannot generate small
101primes. Therefore the number of bits should not be less that 64. For typical
102private keys this will not matter because for security reasons they will
103be much larger (typically 1024 bits).
104
105=head1 SEE ALSO
106
107L<gendsa(1)>
108
109=head1 COPYRIGHT
110
111Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
112
113Licensed under the OpenSSL license (the "License").  You may not use
114this file except in compliance with the License.  You can obtain a copy
115in the file LICENSE in the source distribution or at
116L<https://www.openssl.org/source/license.html>.
117
118=cut
119