了解Blum Blum Shub算法。(Understanding Blum Blum Shub algorithm. (Python implementation))

请帮我理解BBS算法。我做了这个实现：

class EmptySequenseError(Exception): pass class BlumBlumShub(object): def __init__(self, length): self.length = length self.primes = e(1000) # Primes obtained by my own Sieve of Eratosthenes implementation. def get_primes(self): out_primes = [] while len(out_primes) < 2: curr_prime = self.primes.pop() if curr_prime % 4 == 3: out_primes.append(curr_prime) return out_primes def set_random_sequence(self): p, q = self.get_primes() m = p * q self.random_sequence = [((x+1)**2)%m for x in range(self.length)] def get_random_sequence(self): if self.random_sequence: return self.random_sequence raise EmptySequenseError("Set random sequence before get it!")

我有几个问题。起初我不想使用random库，这太天真了。我的顺序在增加，它不是绝对随机的。 如何防止返回序列增加？ 我不明白这部分的算法描述：

在算法的每一步，一些输出从x n + 1导出; 输出通常是x n + 1的位奇偶校验或x n + 1的一个或多个最低有效位。

请向我解释这是什么意思？

编辑总结：

该算法已得到纠正。引用替换为en.wikipedia报价。

Please help me to understand BBS algorithm. I did this implementation:

class EmptySequenseError(Exception): pass class BlumBlumShub(object): def __init__(self, length): self.length = length self.primes = e(1000) # Primes obtained by my own Sieve of Eratosthenes implementation. def get_primes(self): out_primes = [] while len(out_primes) < 2: curr_prime = self.primes.pop() if curr_prime % 4 == 3: out_primes.append(curr_prime) return out_primes def set_random_sequence(self): p, q = self.get_primes() m = p * q self.random_sequence = [((x+1)**2)%m for x in range(self.length)] def get_random_sequence(self): if self.random_sequence: return self.random_sequence raise EmptySequenseError("Set random sequence before get it!")

And I have several questions. At first I do not want to use random library, it is too naive. My sequence is increasing, it is not absolutely random. How to prevent increasing in returned sequence? And I do not understand this part of the algorithm description:

At each step of the algorithm, some output is derived from xn+1; the output is commonly either the bit parity of xn+1 or one or more of the least significant bits of xn+1.

Please explain to me what does it mean?