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RAND(3) 			   LibreSSL			       RAND(3)

NAME

RAND - pseudo-random number generator

SYNOPSIS

#include <openssl/rand.h> int RAND_bytes(unsigned char *buf, int num); int RAND_pseudo_bytes(unsigned char *buf, int num);

DESCRIPTION

These functions give access to the systems cryptographically secure pseudo-random number generator (PRNG). It is used by other library functions for example to generate random keys, and applications can use it when they need randomness. RAND_bytes(3) describes how to obtain random data from the PRNG.

INTERNALS

The RAND_SSLeay() method implements a PRNG based on the systems' arc4random_buf(3) random number generator.

SEE ALSO

BN_rand(3), RAND_bytes(3) LibreSSL 2017-01-09 RAND(3) RAND_load_file(3) OpenSSL RAND_load_file(3)

NAME

RAND_load_file, RAND_write_file, RAND_file_name - PRNG seed file

SYNOPSIS

#include <openssl/rand.h> const char *RAND_file_name(char *buf, size_t num); int RAND_load_file(const char *filename, long max_bytes); int RAND_write_file(const char *filename);

DESCRIPTION

RAND_file_name() generates a default path for the random seed file. buf points to a buffer of size num in which to store the filename. The seed file is $RANDFILE if that environment variable is set, $HOME/.rnd otherwise. If $HOME is not set either, or num is too small for the path name, an error occurs. RAND_load_file() reads a number of bytes from file filename and adds them to the PRNG. If max_bytes is non-negative, up to to max_bytes are read; starting with OpenSSL 0.9.5, if max_bytes is -1, the complete file is read. RAND_write_file() writes a number of random bytes (currently 1024) to file filename which can be used to initialize the PRNG by calling RAND_load_file() in a later session.

RETURN VALUES

RAND_load_file() returns the number of bytes read. RAND_write_file() returns the number of bytes written, and -1 if the bytes written were generated without appropriate seed. RAND_file_name() returns a pointer to buf on success, and NULL on error.

SEE ALSO

rand(3), RAND_add(3), RAND_cleanup(3)

HISTORY

RAND_load_file(), RAND_write_file() and RAND_file_name() are available in all versions of SSLeay and OpenSSL. 1.0.2h 2016-05-03 RAND_load_file(3)

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