A CSPRNG for Lua.

lua >= 5.1

$ luarocks install arc4random

The library provides two methods, random and buf. random is intended to be a drop in replacement for math.random, so it handles three cases.

arc4.random() returns a random floating point number in the range [0,1). arc4.random( n ) and arc4.random( m, n ) return a random integer in the range [1,n] and [m,n] respectively. All three cases match the behavior of math.random so you can do math.random = arc4.random and everything will keep working.

arc4.buf( n ) returns a string of n random characters. It is suitable for generating private encryption keys and IVs.

Some example code:

local arc4 = require( "arc4random" )

print( arc4.random() )
print( arc4.random( 3 ) )
print( arc4.random( -5, 5 ) )

local str = arc4.buf( 16 )
str = str:gsub( "(.)", function( c )
	return ( "%02x" ):format( string.byte( c ) )
end )
print( str )