1Crypt::Random(3)      User Contributed Perl Documentation     Crypt::Random(3)
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NAME

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

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

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

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

25       The /dev/random driver maintains an estimate of true randomness in the
26       pool and decreases it every time random strings are requested for use.
27       When the estimate goes down to zero, the routine blocks and waits for
28       the occurrence of non-deterministic events to refresh the pool.
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30       When the routine is blocked, Crypt::Random's read() will be blocked
31       till desired amount of random bytes have been read off of the device.
32       The /dev/random kernel module also provides another interface,
33       /dev/urandom, that does not wait for the entropy-pool to recharge and
34       returns as many bytes as requested. For applications that must not
35       block (for a potentially long time) should use /dev/urandom.
36       /dev/random should be reserved for instances where very high quality
37       randomness is desired.
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HARDWARE RNG

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

47       makerandom()
48           Generates a random number of requested bitsize in base 10.
49           Following arguments can be specified.
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51           Size
52               Bitsize of the random number.
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54           Strength 0 || 1
55               Value of 1 implies that /dev/random should be used for
56               requesting random bits while 0 implies /dev/urandom.
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58           Device
59               Alternate device to request random bits from.
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61           Uniform 0 || 1
62               Value of 0 (default) implies that the high bit of the generated
63               random number is always set, ensuring the bitsize of the
64               generated random will be exactly Size bits. For uniformly
65               distributed random numbers, Uniform should be set to 1.
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67       makerandom_itv()
68           Generates a random number in the specified interval.  In addition
69           to the arguments to makerandom() following attributes can be
70           specified.
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72           Lower
73               Inclusive Lower limit.
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75           Upper
76               Exclusive Upper limit.
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78       makerandom_octet()
79           Generates a random octet string of specified length. In addition to
80           Strength, Device and Verbosity, following arguments can be
81           specified.
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83           Length
84               Length of the desired octet string.
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86           Skip
87               An octet string consisting of characters to be skipped while
88               reading from the random device.
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DEPENDENCIES

91       Crypt::Random needs Math::Pari 2.001802 or higher.
92

BIBLIOGRAPHY

94       1 random.c by Theodore Ts'o.  Found in drivers/char directory of the
95       Linux kernel sources.
96       2 Handbook of Applied Cryptography by Menezes, Paul C. van Oorschot and
97       Scott Vanstone.
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AUTHOR

100       Vipul Ved Prakash, <mail@vipul.net>
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104perl v5.34.0                      2021-07-22                  Crypt::Random(3)
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