Random(3)

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/ran-
       dom 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

       mmaakkeerraannddoomm(())
           Generates a random number of requested bitsize in base 10. Follow-
           ing arguments can be specified.

           Size
               Bitsize of the random number.

           Strength 0 || 1
               Value of 1 implies that /dev/random should be used for request-
               ing 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 gener-
               ated random will be exactly Size bits. For uniformally distrib-
               uted random numbers, Uniform should be set to 1.

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

           Lower
               Inclusive Lower limit.

           Upper
               Exclusive Upper limit.

       mmaakkeerraannddoomm_oocctteett(())
           Generates a random octet string of specified length. In addition to
           Strength, Device and Verbosity, following arguments can be speci-
           fied.

           Length
               Length of the desired octet string.

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

       Crypt::Random needs Math::Pari 2.001802 or higher. As of this writing,
       the latest version of Math::Pari isn't available from CPAN. Fetch it
       from ftp://ftp.math.ohio-state.edu/pub/users/ilya/perl/modules/

       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.

       Vipul Ved Prakash, <mail@vipul.net>

perl v5.8.6                       2004-06-02                  Crypt::Random(3)