Section: OpenSSL (1)
openssl-rand, rand - generate pseudo-random bytes
This command generates num
random bytes using a cryptographically
secure pseudo random number generator (CSPRNG
The random bytes are generated using the RAND_bytes(3) function,
which provides a security level of 256 bits, provided it managed to
seed itself successfully from a trusted operating system entropy source.
Otherwise, the command will fail with a nonzero error code.
For more details, see RAND_bytes(3), RAND(7), and RAND_DRBG(7).
Print out a usage message.
- -out file
Write to file instead of standard output.
- -rand file...
A file or files containing random data used to seed the random number
Multiple files can be specified separated by an OS-dependent character.
The separator is ; for MS-Windows, , for OpenVMS, and : for
Explicitly specifying a seed file is in general not necessary, see the
``NOTES'' section for more information.
- [-writerand file]
Writes random data to the specified file upon exit.
This can be used with a subsequent -rand flag.
Perform base64 encoding on the output.
Show the output as a hex string.
Prior to OpenSSL 1.1.1, it was common for applications to store information
about the state of the random-number generator in a file that was loaded
at startup and rewritten upon exit. On modern operating systems, this is
generally no longer necessary as OpenSSL will seed itself from a trusted
entropy source provided by the operating system. The -rand
flags are still supported for special platforms or
circumstances that might require them.
It is generally an error to use the same seed file more than once and
every use of -rand should be paired with -writerand.
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Licensed under the OpenSSL license (the ``License''). You may not use
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