Provided by: openssl_1.1.1-1ubuntu2_amd64 bug

NAME

       openssl-genrsa, genrsa - generate an RSA private key

SYNOPSIS

       openssl genrsa [-help] [-out filename] [-passout arg] [-aes128] [-aes192] [-aes256]
       [-aria128] [-aria192] [-aria256] [-camellia128] [-camellia192] [-camellia256] [-des]
       [-des3] [-idea] [-f4] [-3] [-rand file...]  [-writerand file] [-engine id] [-primes num]
       [numbits]

DESCRIPTION

       The genrsa command generates an RSA private key.

OPTIONS

       -help
           Print out a usage message.

       -out filename
           Output the key to the specified file. If this argument is not specified then standard
           output is used.

       -passout arg
           The output file password source. For more information about the format of arg see the
           PASS PHRASE ARGUMENTS section in openssl(1).

       -aes128, -aes192, -aes256, -aria128, -aria192, -aria256, -camellia128, -camellia192,
       -camellia256, -des, -des3, -idea
           These options encrypt the private key with specified cipher before outputting it. If
           none of these options is specified no encryption is used. If encryption is used a pass
           phrase is prompted for if it is not supplied via the -passout argument.

       -F4|-3
           The public exponent to use, either 65537 or 3. The default is 65537.

       -rand file...
           A file or files containing random data used to seed the random number generator.
           Multiple files can be specified separated by an OS-dependent character.  The separator
           is ; for MS-Windows, , for OpenVMS, and : for all others.

       [-writerand file]
           Writes random data to the specified file upon exit.  This can be used with a
           subsequent -rand flag.

       -engine id
           Specifying an engine (by its unique id string) will cause genrsa to attempt to obtain
           a functional reference to the specified engine, thus initialising it if needed. The
           engine will then be set as the default for all available algorithms.

       -primes num
           Specify the number of primes to use while generating the RSA key. The num parameter
           must be a positive integer that is greater than 1 and less than 16.  If num is greater
           than 2, then the generated key is called a 'multi-prime' RSA key, which is defined in
           RFC 8017.

       numbits
           The size of the private key to generate in bits. This must be the last option
           specified. The default is 2048 and values less than 512 are not allowed.

NOTES

       RSA private key generation essentially involves the generation of two or more prime
       numbers. When generating a private key various symbols will be output to indicate the
       progress of the generation. A . represents each number which has passed an initial sieve
       test, + means a number has passed a single round of the Miller-Rabin primality test, *
       means the current prime starts a regenerating progress due to some failed tests. A newline
       means that the number has passed all the prime tests (the actual number depends on the key
       size).

       Because key generation is a random process the time taken to generate a key may vary
       somewhat. But in general, more primes lead to less generation time of a key.

SEE ALSO

       gendsa(1)

COPYRIGHT

       Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use this file except in
       compliance with the License.  You can obtain a copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.