#include <openssl/rand.h> int RAND_bytes(unsigned char *buf, int num); int RAND_priv_bytes(unsigned char *buf, int num);
#if OPENSSL_API_COMPAT < 0x10100000L int RAND_pseudo_bytes(unsigned char *buf, int num); #endif
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).
If the entropy source fails or is not available, the CSPRNG will enter an error state and refuse to generate random bytes. For that reason, it is important to always check the error return value of RAND_bytes() and RAND_priv_bytes() and not take randomness for granted.
On other platforms, there might not be a trusted entropy source available or OpenSSL might have been explicitly configured to use different entropy sources. If you are in doubt about the quality of the entropy source, don't hesitate to ask your operating system vendor or post a question on GitHub or the openssl-users mailing list.
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>.