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	zrand.3 - libzahl - big integer library
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	zrand.3 (2219B)
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	1 .TH ZRAND 3 libzahl
	2 .SH NAME
	3 zrand - Generate random a number
	4 .SH SYNOPSIS
	5 .nf
	6 #include <zahl.h>
	7
	8 void zrand(z_t \fIr\fP, enum zranddev \fIdev\fP, enum zranddist \fIdist\…
	9 .fi
	10 .SH DESCRIPTION
	11 .B zrand
	12 generates a random number and stores it in
	13 .IR r .
	14 .P
	15 .I dev
	16 selects the device
	17 .B zrand
	18 uses to generate random bits.
	19 This value may be either of:
	20 .TP
	21 .B DEFAULT_RANDOM
	22 This is a version-dependent alias for the
	23 default random number generator. That is,
	24 using this option will cause
	25 .B zrand
	26 to select the default random number generator.
	27 Which random number generator is actually
	28 selected may change between versions of
	29 .B zrand.
	30
	31 The selection will be a balance between randomness
	32 and performance.
	33 .TP
	34 .B FASTEST_RANDOM
	35 This is a version-dependent alias for the
	36 fastest random number generator. That is,
	37 using this option will cause
	38 .B zrand
	39 to select the fastest random number generator.
	40 Which random number generator is actually
	41 selected may change between versions of
	42 .B zrand.
	43 .TP
	44 .B FAST_RANDOM
	45 The fast, non-blocking random number generator.
	46 This is /dev/urandom on Linux.
	47 .TP
	48 .B SECURE_RANDOM
	49 The secure, blocking random number generator.
	50 This is /dev/random on Linux.
	51 .P
	52 .I dist
	53 selects the probably distribution of the
	54 output
	55 .IR r :
	56 .TP
	57 .B QUASIUNIFORM
	58 Use the method of generation that is often
	59 recommended for generating uniformally random
	60 integers. This method has unnecessary
	61 computational overhead and is not properly
	62 uniform, but is is guaranteed to run in
	63 constant time assuming the underlying device
	64 for random bit generation does.
	65
	66 The generated number if be in the inclusive
	67 range [0,
	68 .IR max ].
	69 .TP
	70 .B UNIFORM
	71 Generate a integer in the range [0,
	72 .IR max ]
	73 uniformally random.
	74 .TP
	75 .B MODUNIFORM
	76 Slightly faster alternative to
	77 .BR UNIFORM .
	78
	79 It is not truly uniform. It is biased
	80 to the lower numbers, but the probably
	81 if any number is either
	82 .I p
	83 or
	84 .I 2p
	85 for some parameter-dependent number
	86 .IR p .
	87
	88 It uses the naïve approach of generating
	89 a random number and modulation with the maximum
	90 number. However, this implementation this
	91 modulation by subtracting with the maximum number
	92 if the generated number is greater.
	93 .P
	94 It is safe to call
	95 .B zrand
	96 with non-unique parameters.