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.

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 or an openssl with no-egd this function does not exist.

random_status ()

This function returns 1 if the PRNG has sufficient seeding. or 0 if not.

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@cpan.com"

Now maintained by Reini Urban, "rurban@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).