1=pod 2{- OpenSSL::safe::output_do_not_edit_headers(); -} 3 4=head1 NAME 5 6openssl-rand - generate pseudo-random bytes 7 8=head1 SYNOPSIS 9 10B<openssl rand> 11[B<-help>] 12[B<-out> I<file>] 13[B<-base64>] 14[B<-hex>] 15{- $OpenSSL::safe::opt_engine_synopsis -}{- $OpenSSL::safe::opt_r_synopsis -} 16{- $OpenSSL::safe::opt_provider_synopsis -} 17I<num>[K|M|G|T] 18 19=head1 DESCRIPTION 20 21This command generates I<num> random bytes using a cryptographically 22secure pseudo random number generator (CSPRNG). A suffix [K|M|G|T] may be 23appended to the num value to indicate the requested value be scaled as a 24multiple of KiB/MiB/GiB/TiB respectively. Note that suffixes are case 25sensitive, and that the suffixes represent binary multiples 26(K = 1024 bytes, M = 1024*1024 bytes, etc). 27 28The string 'max' may be substituted for a numerical value in num, to request the 29maximum number of bytes the CSPRNG can produce per instantiation. Currently, 30this is restricted to 2^61 bytes as per NIST SP 800-90C. 31 32The random bytes are generated using the L<RAND_bytes(3)> function, 33which provides a security level of 256 bits, provided it managed to 34seed itself successfully from a trusted operating system entropy source. 35Otherwise, the command will fail with a nonzero error code. 36For more details, see L<RAND_bytes(3)>, L<RAND(7)>, and L<EVP_RAND(7)>. 37 38=head1 OPTIONS 39 40=over 4 41 42=item B<-help> 43 44Print out a usage message. 45 46=item B<-out> I<file> 47 48Write to I<file> instead of standard output. 49 50=item B<-base64> 51 52Perform base64 encoding on the output. 53 54=item B<-hex> 55 56Show the output as a hex string. 57 58{- $OpenSSL::safe::opt_engine_item -} 59 60{- $OpenSSL::safe::opt_r_item -} 61 62{- $OpenSSL::safe::opt_provider_item -} 63 64=back 65 66=head1 SEE ALSO 67 68L<openssl(1)>, 69L<RAND_bytes(3)>, 70L<RAND(7)>, 71L<EVP_RAND(7)> 72 73=head1 HISTORY 74 75The B<-engine> option was deprecated in OpenSSL 3.0. 76 77=head1 COPYRIGHT 78 79Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved. 80 81Licensed under the Apache License 2.0 (the "License"). You may not use 82this file except in compliance with the License. You can obtain a copy 83in the file LICENSE in the source distribution or at 84L<https://www.openssl.org/source/license.html>. 85 86=cut 87
