[cHeRsAnYa]

Используется стандартный java'вский Random, а первая же строка в его описании - "An instance of this class is used to generate a stream of pseudorandom numbers. The class uses a 48-bit seed, which is modified using a linear congruential formula. (See Donald Knuth, The Art of Computer Programming, Volume 2, Section 3.2.1.)"