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我查看了多个网站以查找 MD5 算法是什么。然后我用我学到的东西在 Java 中编写了一个可以计算给定输入的 MD5 哈希的方法。我尝试更改我认为不正确的代码的某些部分，但我仍然无法为我尝试的某些字符串获得正确的哈希值。这是我的代码：

    import java.security.MessageDigest;
    import java.security.NoSuchAlgorithmException;

    class MD5 {
    public static void main(String[] args) throws NoSuchAlgorithmException {
        String[] msgs = new String[] { "", "md5", "MD5", "Java",
                "MessageDigest5", "1234", "123abc", "0123456789abcdef" };
        String[] strings = new String[msgs.length + args.length];
        System.arraycopy(msgs, 0, strings, 0, msgs.length);
        for (int i = msgs.length; i < strings.length; ++i)
            strings[i] = args[i - msgs.length];
        for (String s : strings) {
            System.out.print("MD5(\"" + s + "\") = ");
            byte[] md5 = md5(s.getBytes());
            byte[] java = MessageDigest.getInstance("MD5").digest(s.getBytes());
            StringBuilder sbmd5 = new StringBuilder();
            StringBuilder sbjava = new StringBuilder();
            for (int i = 0; i < 16; ++i) {
                sbmd5.append(String.format("%02x", md5[i] & 0xff));
                sbjava.append(String.format("%02x", java[i] & 0xff));
            }
            System.out.print("Java(" + sbjava.toString() + ") MD5(");
            System.out.print(sbmd5.toString() + ")");
            System.out.println();
        }
    }

    public static byte[] md5(byte[] data) {
        if (data == null)
            throw new NullPointerException();
        byte[] padding = new byte[] { (byte) 0x80, 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 };
        int[] SHIFT = new int[] { 7, 12, 17, 22, 5, 9, 14, 20, 4, 11, 16, 23,
                6, 10, 15, 21 };
        int[] TABLE = new int[64];
        for (int i = 0; i < 64; ++i)
            TABLE[i] = (int) (long) ((1L << 32) * Math.abs(Math.sin(i + 1)));
        int A = 0x67452301; // 01234567
        int B = 0xefcdab89; // 89abcdef
        int C = 0x98badcfe; // fedcba98
        int D = 0x10325476; // 76543210
        // int A = 0x01234567;
        // int B = 0x89abcdef;
        // int C = 0xfedcba98;
        // int D = 0x76543210;
        byte[] msg = new byte[data.length + 64 - (data.length % 64)];
        System.arraycopy(data, 0, msg, 0, data.length);
        int padPos = 0;
        for (int i = data.length; i < msg.length; ++i)
            msg[i] = padding[padPos++];
        for (int i = 0; i < msg.length >>> 6; ++i) {
            int[] words = new int[16];
            int msgStart = i << 6;
            for (int j = 0; j < 16; ++j) {
                int k = j << 2;
                int begin = msgStart + k;
                words[j] = msg[begin] + (msg[begin + 1] << 8)
                        + (msg[begin + 2] << 16) + (msg[begin + 3] << 24);
            }
            int a0 = A;
            int b0 = B;
            int c0 = C;
            int d0 = D;
            for (int j = 0; j < 64; ++j) {
                int j16 = j >>> 4;
                int F;
                int index;
                switch (j16) {
                case 0:
                    F = (b0 & c0) | (~b0 & d0);
                    // F = d0 ^ (b0 & (c0 ^ d0));
                    index = j;
                    break;
                case 1:
                    F = (b0 & d0) | (c0 & ~d0);
                    // F = c0 ^ (d0 & (b0 ^ c0));
                    index = ((j * 5) + 1) & 15;
                    break;
                case 2:
                    F = b0 ^ c0 ^ d0;
                    index = ((j * 3) + 5) & 15;
                    break;
                default:
                    F = c0 ^ (b0 | ~d0);
                    index = (j * 7) & 15;
                    break;
                }
                int rotateValue = A + F + words[index] + TABLE[j];
                int rotateDistance = SHIFT[(j16 << 2) | (j & 3)];
                int temp = B
                        + ((rotateValue << rotateDistance) | (rotateValue >>> (32 - rotateDistance)));
                A = D;
                D = C;
                C = B;
                B = temp;
            }
            A += a0;
            B += b0;
            C += c0;
            D += d0;
        }
        byte[] result = new byte[16];
        int index = 0;
        for (int i = 0; i < 4; ++i) {
            int n = i == 0 ? A : (i == 1 ? B : (i == 2 ? C : D));
            for (int j = 0; j < 4; ++j) {
                result[index++] = (byte) n;
                n >>>= 8;
            }
        }
        return result;
    }
}

我不知道它有什么问题，但这是输出。我在我的实现和 java.security.MessageDigest 中对相同的字符串集进行了哈希处理以比较哈希值。

MD5("") = Java(d41d8cd98f00b204e9800998ecf8427e) MD5(6195f07125a3dab6a14e8e929a0ac5bf)
MD5("md5") = Java(1bc29b36f623ba82aaf6724fd3b16718) MD5(f382be5a669dd9ce3095a4aa2e55ff18)
MD5("MD5") = Java(7f138a09169b250e9dcb378140907378) MD5(af2ade546a995a239c94f5776393bfdd)
MD5("Java") = Java(d52387880e1ea22817a72d3759213819) MD5(f512715d4bc0728fd50994d6583d6370)
MD5("MessageDigest5") = Java(c39f3b584476f0fd9303fe2cba34a1de) MD5(85e2d27519fbf97c3f988e9ccb9564a6)
MD5("1234") = Java(81dc9bdb52d04dc20036dbd8313ed055) MD5(51e22a66d259c84c920d11f3b1048263)
MD5("123abc") = Java(a906449d5769fa7361d7ecc6aa3f6d28) MD5(e1254819f3127907cb3e95b3fa3b2e68)
MD5("0123456789abcdef") = Java(4032af8d61035123906e58e067140cc5) MD5(28fcda2be1f449185c73222e3a6e5ca4)
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1 回答 1

-2 
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.logging.Level;
import java.util.logging.Logger;

public void encrypt(){
    String password = new String(jPasswordField1.getPassword());

    MessageDigest algorithm = null;
    try {
        algorithm = MessageDigest.getInstance("MD5");
    } catch (NoSuchAlgorithmException ex) {
        Logger.getLogger(pe.class.getName()).log(Level.SEVERE, null, ex);
    }
    algorithm.reset();
    algorithm.update(password.getBytes());
    byte bytes [] = algorithm.digest();
    StringBuffer sb = new StringBuffer();
    for (byte b : bytes){
         String hex = Integer.toHexString(0xff & b);
         if (hex.length() == 1)
             sb.append('0');
         sb.append(hex);
    }
    String result = sb.toString();
    jTextArea1.setText(result);

}
于 2014-03-24T21:03:50.447 回答