- 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.
- 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.
- 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.
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.
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.