5 genrsa - generate an RSA private key
34 The B<genrsa> command generates an RSA private key.
42 Print out a usage message.
44 =item B<-out filename>
46 Output the key to the specified file. If this argument is not specified then
47 standard output is used.
51 The output file password source. For more information about the format
52 of B<arg> see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
54 =item B<-aes128|-aes192|-aes256|-aria128|-aria192|-aria256|-camellia128|-camellia192|-camellia256|-des|-des3|-idea>
56 These options encrypt the private key with specified
57 cipher before outputting it. If none of these options is
58 specified no encryption is used. If encryption is used a pass phrase is prompted
59 for if it is not supplied via the B<-passout> argument.
63 The public exponent to use, either 65537 or 3. The default is 65537.
65 =item B<-rand file...>
67 A file or files containing random data used to seed the random number
69 Multiple files can be specified separated by an OS-dependent character.
70 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
73 =item [B<-writerand file>]
75 Writes random data to the specified I<file> upon exit.
76 This can be used with a subsequent B<-rand> flag.
80 Specifying an engine (by its unique B<id> string) will cause B<genrsa>
81 to attempt to obtain a functional reference to the specified engine,
82 thus initialising it if needed. The engine will then be set as the default
83 for all available algorithms.
87 The size of the private key to generate in bits. This must be the last option
88 specified. The default is 2048.
94 RSA private key generation essentially involves the generation of two prime
95 numbers. When generating a private key various symbols will be output to
96 indicate the progress of the generation. A B<.> represents each number which
97 has passed an initial sieve test, B<+> means a number has passed a single
98 round of the Miller-Rabin primality test. A newline means that the number has
99 passed all the prime tests (the actual number depends on the key size).
101 Because key generation is a random process the time taken to generate a key
106 A quirk of the prime generation algorithm is that it cannot generate small
107 primes. Therefore the number of bits should not be less that 64. For typical
108 private keys this will not matter because for security reasons they will
109 be much larger (typically 1024 bits).
117 Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
119 Licensed under the OpenSSL license (the "License"). You may not use
120 this file except in compliance with the License. You can obtain a copy
121 in the file LICENSE in the source distribution or at
122 L<https://www.openssl.org/source/license.html>.