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, <mail@vipul.net>

