MD5摘要算法源码

public class MD5 {
    private static final byte[] PADDING = {
            -128, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
        };
    private static final int S11 = 7;
    private static final int S12 = 12;
    private static final int S13 = 17;
    private static final int S14 = 22;
    private static final int S21 = 5;
    private static final int S22 = 9;
    private static final int S23 = 14;
    private static final int S24 = 20;
    private static final int S31 = 4;
    private static final int S32 = 11;
    private static final int S33 = 16;
    private static final int S34 = 23;
    private static final int S41 = 6;
    private static final int S42 = 10;
    private static final int S43 = 15;
    private static final int S44 = 21;
    private long[] state = new long[4]; // state(ABCD)
    private long[] count = new long[2]; // number of bits, modulo 2^64
    private byte[] buffer = new byte[64]; // input buffer
    private String digestHexStr;
    private byte[] digest = new byte[16];

    public MD5() {
        md5Init();

        return;
    }

    public String getMD5ofString(byte[] inbuf, int buflen) {
        getMD5ofByte(inbuf, buflen);
        digestHexStr = "";

        for (int i = 0; i < 16; i++) {
            digestHexStr += byteHEX(digest[i]);
        }

        return digestHexStr;
    }

    public byte[] getMD5ofByte(byte[] inbuf, int buflen) {
        md5Init();
        md5Update(inbuf, buflen);
        md5Final();

        return digest;
    }

    private void md5Init() {
        count[0] = 0L;
        count[1] = 0L;
        state[0] = 0x67452301L;
        state[1] = 0xefcdab89L;
        state[2] = 0x98badcfeL;
        state[3] = 0x10325476L;

        return;
    }

    private long F(long x, long y, long z) {
        return (x & y) | ((~x) & z);
    }

    private long G(long x, long y, long z) {
        return (x & z) | (y & (~z));
    }

    private long H(long x, long y, long z) {
        return x ^ y ^ z;
    }

    private long I(long x, long y, long z) {
        return y ^ (x | (~z));
    }

    private long FF(long a, long b, long c, long d, long x, long s, long ac) {
        a += (F(b, c, d) + x + ac);
        a = ((int) a << s) | ((int) a >>> (32 - s));
        a += b;

        return a;
    }

    private long GG(long a, long b, long c, long d, long x, long s, long ac) {
        a += (G(b, c, d) + x + ac);
        a = ((int) a << s) | ((int) a >>> (32 - s));
        a += b;

        return a;
    }

    private long HH(long a, long b, long c, long d, long x, long s, long ac) {
        a += (H(b, c, d) + x + ac);
        a = ((int) a << s) | ((int) a >>> (32 - s));
        a += b;

        return a;
    }

    private long II(long a, long b, long c, long d, long x, long s, long ac) {
        a += (I(b, c, d) + x + ac);
        a = ((int) a << s) | ((int) a >>> (32 - s));
        a += b;

        return a;
    }

    private void md5Update(byte[] inbuf, int inputLen) {
        int i;
        int index;
        int partLen;
        byte[] block = new byte[64];
        index = (int) (count[0] >>> 3) & 0x3F;

        // Update number of bits
        if ((count[0] += (inputLen << 3)) < (inputLen << 3)) {
            count[1]++;
        }

        count[1] += (inputLen >>> 29);
        partLen = 64 - index;

        // Transform as many times as possible.
        if (inputLen >= partLen) {
            md5Memcpy(buffer, inbuf, index, 0, partLen);
            md5Transform(buffer);

            for (i = partLen; (i + 63) < inputLen; i += 64) {
                md5Memcpy(block, inbuf, 0, i, 64);
                md5Transform(block);
            }

            index = 0;
        } else {
            i = 0;
        }

        // Buffer remaining input
        md5Memcpy(buffer, inbuf, index, i, inputLen - i);
    }

    private void md5Final() {
        byte[] bits = new byte[8];