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


  use Crypt::OpenSSL::Random;

  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);


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.


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 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.


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.


Ian Robertson,

Now maintained by Reini Urban,


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


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