RAND_bytes(3)

NAME
RAND_bytes, RAND_priv_bytes, RAND_pseudo_bytes - generate random data

LIBRARY
libcrypto, -lcrypto

SYNOPSIS
 #include <openssl/rand.h>

 int RAND_bytes(unsigned char *buf, int num);
 int RAND_priv_bytes(unsigned char *buf, int num);

Deprecated:

 #if OPENSSL_API_COMPAT < 0x10100000L
 int RAND_pseudo_bytes(unsigned char *buf, int num);
 #endif

DESCRIPTION
RAND_bytes() puts num cryptographically strong pseudo-random bytes into buf.

RAND_priv_bytes() has the same semantics as RAND_bytes(). It is intended to be used for generating values that should remain private. If using the default RAND_METHOD, this function uses a separate "private" PRNG instance so that a compromise of the "public" PRNG instance will not affect the secrecy of these private values, as described in RAND(7) and RAND_DRBG(7).

NOTES
Always check the error return value of RAND_bytes() and RAND_priv_bytes() and do not take randomness for granted: an error occurs if the CSPRNG has not been seeded with enough randomness to ensure an unpredictable byte sequence.

RETURN VALUES
RAND_bytes() and RAND_priv_bytes() return 1 on success, -1 if not supported by the current RAND method, or 0 on other failure. The error code can be obtained by ERR_get_error(3).

SEE ALSO
RAND_add(3), RAND_bytes(3), RAND_priv_bytes(3), ERR_get_error(3), RAND(7), RAND_DRBG(7)

HISTORY

•   RAND_pseudo_bytes() was deprecated in OpenSSL 1.1.0; use RAND_bytes() instead.

•   The RAND_priv_bytes() function was added in OpenSSL 1.1.1.

COPYRIGHT
Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (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 <https://www.openssl.org/source/license.html>.