phpman > perldoc > Crypt::OpenSSL::Random

NAME
    Crypt::OpenSSL::Random - OpenSSL/LibreSSL pseudo-random number generator access

SYNOPSIS
      use Crypt::OpenSSL::Random;

      Crypt::OpenSSL::Random::random_seed($good_random_data);
      Crypt::OpenSSL::Random::random_egd("/tmp/entropy");
      Crypt::OpenSSL::Random::random_status() or
        die "Unable to sufficiently seed the random number generator".

      my $ten_good_random_bytes = Crypt::OpenSSL::Random::random_bytes(10);
      my $ten_ok_random_bytes = Crypt::OpenSSL::Random::random_pseudo_bytes(10);

DESCRIPTION
    "Crypt::OpenSSL::Random" provides the ability to seed and query the OpenSSL and LibreSSL
    library's pseudo-random number generators.

    Note: On LibreSSL "random_egd()" is not defined.

  EXPORT
    None by default.

Static Methods
    random_bytes (IV num_bytes)
        This function, returns a specified number of cryptographically strong pseudo-random bytes
        from the PRNG. If the PRNG has not been seeded with enough randomness to ensure an
        unpredictable byte sequence, then a false value is returned.

    random_pseudo_bytes (IV num_bytes)
        This function, is similar to "random_bytes", but the resulting sequence of bytes 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.

    random_seed (PV random_bytes_string)
        This function seeds the PRNG with a supplied string of bytes. It returns true if the PRNG
        has sufficient seeding. Note: calling this function with non-random bytes is of limited
        value at best!

    random_egd (PV egd_string)
        This function seeds the PRNG with data from the specified entropy gathering daemon. Returns
        the number of bytes read from the daemon on success, or -1 if not enough bytes were read, or
        if the connection to the daemon failed.

        "libressl" considers this function insecure, so with libressl this function does not exist.

    random_status ()
        This function returns true if the PRNG has sufficient seeding.

BUGS
    Because of the internal workings of OpenSSL's random library, the pseudo-random number generator
    (PRNG) accessed by Crypt::OpenSSL::Random will be different than the one accessed by any other
    perl module. Hence, to use a module such as Crypt::OpenSSL::Random, you will need to seed the
    PRNG used there from one used here. This class is still advantageous, however, as it centralizes
    other methods, such as "random_egd", in one place.

AUTHOR
    Ian Robertson, "iroberts AT cpan.com"

    Now maintained by Reini Urban, "rurban AT cpan.org"

LICENSE
    This module is available under the same licences as perl, the Artistic license and the GPL.

SEE ALSO
    perl(1), rand(3), RAND_add(3), RAND_egd(3), RAND_bytes(3).