"Fossies" - the Fresh Open Source Software Archive

Member "openssl-1.0.2q/doc/crypto/RAND_bytes.pod" (20 Nov 2018, 1537 Bytes) of package /linux/misc/openssl-1.0.2q.tar.gz:


Caution: As a special service "Fossies" has tried to format the requested pod source page into HTML format but links to other pod pages may be missing or even errorneous. Alternatively you can here view or download the uninterpreted pod source code. A member file download can also be achieved by clicking within a package contents listing on the according byte size field. See also the last Fossies "Diffs" side-by-side code changes report for "RAND_bytes.pod": 1.1.0g_vs_1.1.1-pre2.

NAME

RAND_bytes, RAND_pseudo_bytes - generate random data

SYNOPSIS

 #include <openssl/rand.h>

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

 int RAND_pseudo_bytes(unsigned char *buf, int num);

DESCRIPTION

RAND_bytes() puts num cryptographically strong pseudo-random bytes into buf. An error occurs if the PRNG has not been seeded with enough randomness to ensure an unpredictable byte sequence.

RAND_pseudo_bytes() puts num pseudo-random bytes into buf. Pseudo-random byte sequences generated by RAND_pseudo_bytes() will be unique if they are of sufficient length, but are not necessarily unpredictable. They can be used for non-cryptographic purposes and for certain purposes in cryptographic protocols, but usually not for key generation etc.

The contents of buf is mixed into the entropy pool before retrieving the new pseudo-random bytes unless disabled at compile time (see FAQ).

RETURN VALUES

RAND_bytes() returns 1 on success, 0 otherwise. The error code can be obtained by ERR_get_error(3). RAND_pseudo_bytes() returns 1 if the bytes generated are cryptographically strong, 0 otherwise. Both functions return -1 if they are not supported by the current RAND method.

SEE ALSO

rand(3), ERR_get_error(3), RAND_add(3)

HISTORY

RAND_bytes() is available in all versions of SSLeay and OpenSSL. It has a return value since OpenSSL 0.9.5. RAND_pseudo_bytes() was added in OpenSSL 0.9.5.