我通过执行BigInteger.leftShift(int n)方法将Java二进制密钥与Java BigIntegers一起移位. N(Kn)的关键取决于Kn-1的移位结果.我得到的问题是,我在生成每个密钥后打印出结果,并且转移不是预期的输出.密钥分为2 Cn和Dn(分别为左和右).@H_403_3@
我特意尝试这个:
“要进行左移,将每个位移到左边一个位置,除了第一个位,循环到块的末尾.”@H_403_3@
根据转变,似乎最终会对O进行攻击.不知道如何纠正这个问题.@H_403_3@
结果:@H_403_3@
c0:11110101010100110011000011110@H_403_3@
d0:11110001111001100110101010100@H_403_3@
c1:111101010101001100110000111100@H_403_3@
d1:111100011110011001101010101000@H_403_3@
c2:11110101010100110011000011110000@H_403_3@
d2:11110001111001100110101010100000@H_403_3@
c3:1111010101010011001100001111000000@H_403_3@
d3:1111000111100110011010101010000000@H_403_3@
c4:111101010101001100110000111100000000@H_403_3@
d4:111100011110011001101010101000000000@H_403_3@
c5:11110101010100110011000011110000000000@H_403_3@
d5:11110001111001100110101010100000000000@H_403_3@
c6:1111010101010011001100001111000000000000@H_403_3@
d6:1111000111100110011010101010000000000000@H_403_3@
c7:111101010101001100110000111100000000000000@H_403_3@
d7:111100011110011001101010101000000000000000@H_403_3@
c8:1111010101010011001100001111000000000000000@H_403_3@
d8:1111000111100110011010101010000000000000000@H_403_3@
c9:111101010101001100110000111100000000000000000@H_403_3@
d9:111100011110011001101010101000000000000000000@H_403_3@
c10:11110101010100110011000011110000000000000000000@H_403_3@
d10:11110001111001100110101010100000000000000000000@H_403_3@
c11:1111010101010011001100001111000000000000000000000@H_403_3@
d11:1111000111100110011010101010000000000000000000000@H_403_3@
c12:111101010101001100110000111100000000000000000000000@H_403_3@
d12:111100011110011001101010101000000000000000000000000@H_403_3@
c13:11110101010100110011000011110000000000000000000000000@H_403_3@
d13:11110001111001100110101010100000000000000000000000000@H_403_3@
c14:1111010101010011001100001111000000000000000000000000000@H_403_3@
d14:11110001111001100110101010100000000000000000000000000000000@H_403_3@
c15:11110101010100110011000011110000000000000000000000000000@H_403_3@
d15:111100011110011001101010101000000000000000000000000000000000@H_403_3@
解决方法
private static BigInteger rotateLeft(BigInteger bi) { BigInteger ret = bi.shiftLeft(1); if (ret.testBit(32)) { ret = ret.clearBit(32).setBit(0); } return ret; }
对于32位数字来说,这将是相当低效的,所以你也可以使用原语来旋转DES的28位数.我不熟悉DES算法,所以我假设你需要BigInteger来做其他事情.@H_403_3@
private static BigInteger rotateLeftPrimitive(BigInteger bi) { int value = bi.intValue(); return BigInteger.valueOf(((value << 1) & 0xffffffe) | ((value >>> 27) & 1)); }