=pod
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=head1 NAME
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RAND_bytes, RAND_pseudo_bytes - generate random data
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=head1 SYNOPSIS
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#include <openssl/rand.h>
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int RAND_bytes(unsigned char *buf, int num);
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int RAND_pseudo_bytes(unsigned char *buf, int num);
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=head1 DESCRIPTION
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RAND_bytes() puts B<num> cryptographically strong pseudo-random bytes
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into B<buf>. An error occurs if the PRNG has not been seeded with
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enough randomness to ensure an unpredictable byte sequence.
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RAND_pseudo_bytes() puts B<num> pseudo-random bytes into B<buf>.
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Pseudo-random byte sequences generated by RAND_pseudo_bytes() will be
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unique if they are of sufficient length, but are not necessarily
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unpredictable. They can be used for non-cryptographic purposes and for
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certain purposes in cryptographic protocols, but usually not for key
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generation etc.
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The contents of B<buf> is mixed into the entropy pool before retrieving
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the new pseudo-random bytes unless disabled at compile time (see FAQ).
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=head1 RETURN VALUES
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RAND_bytes() returns 1 on success, 0 otherwise. The error code can be
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obtained by L<ERR_get_error(3)|ERR_get_error(3)>. RAND_pseudo_bytes() returns 1 if the
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bytes generated are cryptographically strong, 0 otherwise. Both
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functions return -1 if they are not supported by the current RAND
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method.
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=head1 SEE ALSO
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L<rand(3)|rand(3)>, L<ERR_get_error(3)|ERR_get_error(3)>,
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L<RAND_add(3)|RAND_add(3)>
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=head1 HISTORY
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RAND_bytes() is available in all versions of SSLeay and OpenSSL. It
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has a return value since OpenSSL 0.9.5. RAND_pseudo_bytes() was added
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in OpenSSL 0.9.5.
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=cut
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