求一个循环群的生成元，用java代码实现

[watchdog2015]

题目：编写一个函数求循环群的一个生成元，使用java代码实现

函数输入：一个大素数p，类型为BigInteger

函数返回值：输出素域p的一个生成元g，类型为BigInteger

[qq_38351849]

public static BigInteger getG(BigInteger p, BigInteger p_MinusOne) {
BigInteger g = null;

outterLoop: for (int i = 2; i < 50; i++) {
for (int x1 = 1; x1 <= Integer.valueOf(p_MinusOne.toString()); x1++) {
String str1 = String.valueOf(i);
String str2 = String.valueOf(x1);
BigInteger tmp1 = new BigInteger(str1);
BigInteger tmp2 = new BigInteger(str2);
if (tmp1.modPow(tmp2, p).compareTo(ONE) == 0 && tmp2.compareTo(p_MinusOne) == -1) {
break;
} else if (tmp1.modPow(tmp2, p).compareTo(ONE) == 0 && tmp2.compareTo(p_MinusOne) == 0) {
g = tmp1;
break outterLoop;
}
}
}

return g;
}

[AttackMonster]

引用 1 楼 qq_38351849 的回复:

public static BigInteger getG(BigInteger p, BigInteger p_MinusOne) { BigInteger g = null; outterLoop: for (int i = 2; i < 50; i++) { for (int x1 = 1; x1 <= Integer.valueOf(p_MinusOne.toString()); x1++) { String str1 = String.valueOf(i); String str2 = String.valueOf(x1); BigInteger tmp1 = new BigInteger(str1); BigInteger tmp2 = new BigInteger(str2); if (tmp1.modPow(tmp2, p).compareTo(ONE) == 0 && tmp2.compareTo(p_MinusOne) == -1) { break; } else if (tmp1.modPow(tmp2, p).compareTo(ONE) == 0 && tmp2.compareTo(p_MinusOne) == 0) { g = tmp1; break outterLoop; } } } return g; }

p_minusOne 是什么意思