Manual: openssl-rand

OPENSSL-RAND(1SSL)					   OpenSSL					  OPENSSL-RAND(1SSL)

NAME
       openssl-rand - generate pseudo-random bytes

SYNOPSIS
       openssl rand [-help] [-out file] [-base64] [-hex] [-engine id] [-rand files] [-writerand file] [-provider name]
       [-provider-path path] [-provparam [name:]key=value] [-propquery propq] num[K|M|G|T]

DESCRIPTION
       This command generates num random bytes using a cryptographically secure pseudo random number generator (CSPRNG). A
       suffix [K|M|G|T] may be appended to the num value to indicate the requested value be scaled as a multiple of
       KiB/MiB/GiB/TiB respectively. Note that suffixes are case sensitive, and that the suffixes represent binary multiples
       (K = 1024 bytes, M = 1024*1024 bytes, etc).

       The string 'max' may be substituted for a numerical value in num, to request the maximum number of bytes the CSPRNG
       can produce per instantiation.  Currently, this is restricted to 2^61 bytes as per NIST SP 800-90C.

       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 EVP_RAND(7).

OPTIONS
       -help
	   Print out a usage message.

       -out file
	   Write to file instead of standard output.

       -base64
	   Perform base64 encoding on the output.

       -hex
	   Show the output as a hex string.

       -engine id
	   See "Engine Options" in openssl(1).	This option is deprecated.

       -rand files, -writerand file
	   See "Random State Options" in openssl(1) for details.

       -provider name
       -provider-path path
       -provparam [name:]key=value
       -propquery propq
	   See "Provider Options" in openssl(1), provider(7), and property(7).

SEE ALSO
       openssl(1), RAND_bytes(3), RAND(7), EVP_RAND(7)

HISTORY
       The -engine option was deprecated in OpenSSL 3.0.

COPYRIGHT
       Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed	 under	the  Apache  License  2.0  (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
       .

3.5.5							 2026-01-27					  OPENSSL-RAND(1SSL)