NAME

   Crypt::Random - Cryptographically Secure, True Random Number Generator.

VERSION

    $Revision: 1.11 $
    $Date: 2001/07/12 15:59:47 $

SYNOPSIS

    use Crypt::Random qw( makerandom );
    my $r = makerandom ( Size => 512, Strength => 1 );

DESCRIPTION

   Crypt::Random is an interface module to the /dev/random device found on
   most modern unix systems. It also interfaces with egd, a user space
   entropy gathering daemon, available for systems where /dev/random (or
   similar) devices are not available. When Math::Pari is installed,
   Crypt::Random can generate random integers of arbritary size of a given
   bitsize or in a specified interval.

BLOCKING BEHAVIOUR

   The /dev/random driver maintains an estimate of true randomness in the
   pool and decreases it every time random strings are requested for use.
   When the estimate goes down to zero, the routine blocks and waits for
   the occurrence of non-deterministic events to refresh the pool.

   When the routine is blocked, Crypt::Random's read() will be blocked
   till desired amount of random bytes have been read off of the device.
   The /dev/random kernel module also provides another interface,
   /dev/urandom, that does not wait for the entropy-pool to recharge and
   returns as many bytes as requested. For applications that must not
   block (for a potentially long time) should use /dev/urandom.
   /dev/random should be reserved for instances where very high quality
   randomness is desired.

HARDWARE RNG

   If there's a hardware random number generator available, for instance
   the Intel i8x0 random number generator, please use it instead of
   /dev/random!. It'll be high quality, a lot faster and it won't block!
   Usually your OS will provide access to the RNG as a device, eg
   (/dev/intel_rng).

METHODS

   makerandom()

     Generates a random number of requested bitsize in base 10. Following
     arguments can be specified.

     Size

       Bitsize of the random number.

     Strength 0 || 1

       Value of 1 implies that /dev/random should be used for requesting
       random bits while 0 implies /dev/urandom.

     Device

       Alternate device to request random bits from.

     Uniform 0 || 1

       Value of 0 (default) implies that the high bit of the generated
       random number is always set, ensuring the bitsize of the generated
       random will be exactly Size bits. For uniformally distributed
       random numbers, Uniform should be set to 1.

   makerandom_itv()

     Generates a random number in the specified interval. In addition to
     the arguments to makerandom() following attributes can be specified.

     Lower

       Inclusive Lower limit.

     Upper

       Exclusive Upper limit.

   makerandom_octet()

     Generates a random octet string of specified length. In addition to
     Strength, Device and Verbosity, following arguments can be specified.

     Length

       Length of the desired octet string.

     Skip

       An octet string consisting of characters to be skipped while
       reading from the random device.

DEPENDENCIES

   Crypt::Random needs Math::Pari 2.001802 or higher.

BIBLIOGRAPHY

   1 random.c by Theodore Ts'o. Found in drivers/char directory of the
   Linux kernel sources.

   2 Handbook of Applied Cryptography by Menezes, Paul C. van Oorschot and
   Scott Vanstone.

AUTHOR

   Vipul Ved Prakash, <[email protected]>