Name

RAND_load_file, RAND_write_file
RAND_file_name

PRNG seed file

Library

libcrypto.lib

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);

Detailed 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 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() always returns a NULL value.

See Also

rand(), RAND_add(), RAND_cleanup()

History

RAND_load_file(), RAND_write_file() and RAND_file_name() are available in all versions of SSLeay and OpenSSL.

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