Initial Commit

openssl-1.0.2f/doc/crypto/RAND_bytes.pod

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