md5.java

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/**
 * MD5 算法的Java Bean
 */
package jaoso.framework.util;


/**
 * md5 类实现了RSA Data Security, Inc.在提交给IETF 的RFC1321中的MD5 message-digest 算法。
 */
public final class MD5 {

    //~ Static fields/initializers =============================================

    /* 下面这些S11-S44实际上是一个4*4的矩阵，在原始的C实现中是用#define 实现的，
    这里把它们实现成为static final是表示了只读，切能在同一个进程空间内的多个
    Instance间共享*/

    /** DOCUMENT ME! */
    private static final int S11 = 7;

    /** DOCUMENT ME! */
    private static final int S12 = 12;

    /** DOCUMENT ME! */
    private static final int S13 = 17;

    /** DOCUMENT ME! */
    private static final int S14 = 22;

    /** DOCUMENT ME! */
    private static final int S21 = 5;

    /** DOCUMENT ME! */
    private static final int S22 = 9;

    /** DOCUMENT ME! */
    private static final int S23 = 14;

    /** DOCUMENT ME! */
    private static final int S24 = 20;

    /** DOCUMENT ME! */
    private static final int S31 = 4;

    /** DOCUMENT ME! */
    private static final int S32 = 11;

    /** DOCUMENT ME! */
    private static final int S33 = 16;

    /** DOCUMENT ME! */
    private static final int S34 = 23;

    /** DOCUMENT ME! */
    private static final int S41 = 6;

    /** DOCUMENT ME! */
    private static final int S42 = 10;

    /** DOCUMENT ME! */
    private static final int S43 = 15;

    /** DOCUMENT ME! */
    private static final int S44 = 21;

    /** DOCUMENT ME! */
    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
        };

    //~ Instance fields ========================================================

    /* digestHexStr是MD5的唯一一个公共成员，是最新一次计算结果的
    　 16进制ASCII表示.
    */

    /** DOCUMENT ME! */
    private String digestHexStr;

    // number of bits, modulo 2^64 (lsb first)

    /** DOCUMENT ME! */
    private byte[] buffer = new byte[64]; // input buffer

    /** DOCUMENT ME! */
    private long[] count = new long[2];

    /* digest,是最新一次计算结果的2进制内部表示，表示128bit的MD5值.
    */

    /** DOCUMENT ME! */
    private byte[] digest = new byte[16];

    /* 下面的三个成员是MD5计算过程中用到的3个核心数据，在原始的C实现中
       被定义到MD5_CTX结构中

     */

    /** DOCUMENT ME! */
    private long[] state = new long[4]; // state (ABCD)

    //~ Constructors ===========================================================

    // 这是MD5这个类的标准构造函数，JavaBean要求有一个public的并且没有参数的构造函数
    public MD5() {

        md5Init();

        return;
    }

    //~ Methods ================================================================

    /**
     * DOCUMENT ME!
     *
     * @param source DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    public static String toMD5(String source) {

        MD5 md5 = new MD5();

        return md5.getMD5ofStr(source);
    }

    /*
      getMD5ofStr是类MD5最主要的公共方法，入口参数是你想要进行MD5变换的字符串
      返回的是变换完的结果，这个结果是从公共成员digestHexStr取得的．
    */
    private String getMD5ofStr(String inbuf) {

        md5Init();
        md5Update(inbuf.getBytes(), inbuf.length());
        md5Final();
        digestHexStr = "";

        for (int i = 0; i < 16; i++) {

            digestHexStr += byteHEX(digest[i]);
        }

        return digestHexStr;
    }

    /*Decode把byte数组按顺序合成成long数组，因为java的long类型是64bit的，
      只合成低32bit，高32bit清零，以适应原始C实现的用途
    */
    private void Decode(long[] output, byte[] input, int len) {

        int i;
        int j;

        for (i = 0, j = 0; j < len; i++, j += 4) {

            output[i] = b2iu(input[j]) | (b2iu(input[j + 1]) << 8)
                | (b2iu(input[j + 2]) << 16) | (b2iu(input[j + 3]) << 24);
        }

        return;
    }

    /*Encode把long数组按顺序拆成byte数组，因为java的long类型是64bit的，
      只拆低32bit，以适应原始C实现的用途
    */
    private void Encode(byte[] output, long[] input, int len) {

        int i;
        int j;

        for (i = 0, j = 0; j < len; i++, j += 4) {

            output[j] = (byte) (input[i] & 0xffL);
            output[j + 1] = (byte) ((input[i] >>> 8) & 0xffL);
            output[j + 2] = (byte) ((input[i] >>> 16) & 0xffL);
            output[j + 3] = (byte) ((input[i] >>> 24) & 0xffL);
        }
    }

    /* F, G, H ,I 是4个基本的MD5函数，在原始的MD5的C实现中，由于它们是
    简单的位运算，可能出于效率的考虑把它们实现成了宏，在java中，我们把它们
    　　实现成了private方法，名字保持了原来C中的。 */
    private long F(long x, long y, long z) {

        return (x & y) | ((~x) & z);
    }

    /*
       FF,GG,HH和II将调用F,G,H,I进行近一步变换
       FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
       Rotation is separate from addition to prevent recomputation.
    */
    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;
    }

    /**
     * DOCUMENT ME!
     *
     * @param x DOCUMENT ME!
     * @param y DOCUMENT ME!
     * @param z DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    private long G(long x, long y, long z) {

        return (x & z) | (y & (~z));
    }

    /**
     * DOCUMENT ME!
     *
     * @param a DOCUMENT ME!
     * @param b DOCUMENT ME!
     * @param c DOCUMENT ME!
     * @param d DOCUMENT ME!
     * @param x DOCUMENT ME!
     * @param s DOCUMENT ME!
     * @param ac DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    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;
    }

    /**
     * DOCUMENT ME!
     *
     * @param x DOCUMENT ME!
     * @param y DOCUMENT ME!
     * @param z DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    private long H(long x, long y, long z) {

        return x ^ y ^ z;
    }

    /**
     * DOCUMENT ME!
     *
     * @param a DOCUMENT ME!
     * @param b DOCUMENT ME!
     * @param c DOCUMENT ME!
     * @param d DOCUMENT ME!
     * @param x DOCUMENT ME!
     * @param s DOCUMENT ME!
     * @param ac DOCUMENT ME!