SecureRandom是强随机数生成器,主要应用的场景为:用于安全目的的数据数,例如生成秘钥或者会话标示(session ID),弱随机数生成器会产生严重的安全问题,而使用SecureRandom这样的强随机数生成器将会极大的降低出问题的风险。

SecureRandom与Random有很强的关系。

1. SecureRandom继承于Random,看一下它的两个构造函数构造函数:

public SecureRandom()
{
super(0);//调用Random的构造函数
getDefaultPRNG(false, null);
}
public SecureRandom(byte seed[])
{
super(0);//调用Random的构造函数
getDefaultPRNG(true, seed);
}

2. SecureRandom与Random的常见的两个方法如下所示:

获得一个随机的int数:

public int nextInt() {
return next(32);
}

next方法如下:

protected int next(int bits) {
long oldseed, nextseed;
AtomicLong seed = this.seed;
do {
oldseed = seed.get();
nextseed = (oldseed * multiplier + addend) & mask;
} while (!seed.compareAndSet(oldseed, nextseed));
return (int)(nextseed >>> (48 - bits));
}

获得随机的字节数组:

synchronized public void nextBytes(byte[] bytes)
{
secureRandomSpi.engineNextBytes(bytes);
}

获得别的随机数的方法见下图:

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" 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想更深入的SecureRandom研究文章,请参考别的资料。

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