RAND_bytes, RAND_priv_bytes, RAND_pseudo_bytes - generate random data
#include <openssl/rand.h> int RAND_bytes(unsigned char *buf, int num); int RAND_priv_bytes(unsigned char *buf, int num);
Deprecated since OpenSSL 1.1.0, can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):
int RAND_pseudo_bytes(unsigned char *buf, int num);
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).
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.
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).
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.
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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 https://www.openssl.org/source/license.html.