Encryption-基础：MD5加密

环境：vc2003 

.h

/* MD5.H - header file for MD5C.C
 */

/* Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
rights reserved.

License to copy and use this software is granted provided that it
is identified as the "RSA Data Security, Inc. MD5 Message-Digest
Algorithm" in all material mentioning or referencing this software
or this function.

License is also granted to make and use derivative works provided
that such works are identified as "derived from the RSA Data
Security, Inc. MD5 Message-Digest Algorithm" in all material
mentioning or referencing the derived work.

RSA Data Security, Inc. makes no representations concerning either
the merchantability of this software or the suitability of this
software for any particular purpose. It is provided "as is"
without express or implied warranty of any kind.

These notices must be retained in any copies of any part of this
documentation and/or software.
 */

#ifndef MD5_SECRIT_H__
#define MD5_SECRIT_H__

namespace SECRIET
{
    /* MD5 context. */
    typedef unsigned int uint32_t;
    typedef struct {
    uint32_t state[4];            /* state (ABCD) */
    uint32_t count[2];            /* number of bits, modulo 2^64 (lsb first) */
    unsigned char buffer[64];     /* input buffer */
    } MD5_CTX;

    void MD5Init(MD5_CTX *context);
    void MD5Update(MD5_CTX *context, unsigned char *input, unsigned int inputLen);
    void MD5Final(unsigned char digest[16], MD5_CTX *context);

    class CMD5
    {
    public:
        MD5_CTX _ctxMd5;

    public:
        CMD5() {MD5Init(&_ctxMd5);}
        ~CMD5() {}

    public:
        void Encode( unsigned char *input, unsigned int inputLen, unsigned char digest[16] )
        {
            MD5Update( &_ctxMd5, input, inputLen );
            MD5Final( digest, &_ctxMd5);
        }

    };
}
#endif

.cpp

/*
 * MD5C.C - RSA Data Security, Inc., MD5 message-digest algorithm
 */

/*
 * Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All rights
 * reserved.
 * 
 * License to copy and use this software is granted provided that it is
 * identified as the "RSA Data Security, Inc. MD5 Message-Digest Algorithm"
 * in all material mentioning or referencing this software or this function.
 * 
 * License is also granted to make and use derivative works provided that such
 * works are identified as "derived from the RSA Data Security, Inc. MD5
 * Message-Digest Algorithm" in all material mentioning or referencing the
 * derived work.
 * 
 * RSA Data Security, Inc. makes no representations concerning either the
 * merchantability of this software or the suitability of this software for
 * any particular purpose. It is provided "as is" without express or implied
 * warranty of any kind.
 * 
 * These notices must be retained in any copies of any part of this
 * documentation and/or software.
 */

#include "Stdafx.h"
#include "md5.h"

/*
 * Constants for MD5Transform routine.
 */
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21

namespace SECRIET
{

    static unsigned char PADDING[64] = {
        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
    };

    /*
    * F, G, H and I are basic MD5 functions.
    */
    #define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
    #define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
    #define H(x, y, z) ((x) ^ (y) ^ (z))
    #define I(x, y, z) ((y) ^ ((x) | (~z)))

    /*
    * ROTATE_LEFT rotates x left n bits.
    */
    #define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

    /*
    * FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4. Rotation is
    * separate from addition to prevent recomputation.
    */
    #define FF(a, b, c, d, x, s, ac) { \
    (a) += F ((b), (c), (d)) + (x) + (uint32_t)(ac); \
    (a) = ROTATE_LEFT ((a), (s)); \
    (a) += (b); \
    }
    #define GG(a, b, c, d, x, s, ac) { \
    (a) += G ((b), (c), (d)) + (x) + (uint32_t)(ac); \
    (a) = ROTATE_LEFT ((a), (s)); \
    (a) += (b); \
    }
    #define HH(a, b, c, d, x, s, ac) { \
    (a) += H ((b), (c), (d)) + (x) + (uint32_t)(ac); \
    (a) = ROTATE_LEFT ((a), (s)); \
    (a) += (b); \
    }
    #define II(a, b, c, d, x, s, ac) { \
    (a) += I ((b), (c), (d)) + (x) + (uint32_t)(ac); \
    (a) = ROTATE_LEFT ((a), (s)); \
    (a) += (b); \
    }

    /*
    * Encodes input (uint32_t) into output (unsigned char). Assumes len is a
    * multiple of 4.
    */
    static void 
    Encode(unsigned char *output, uint32_t * input, unsigned int len)
    {
        unsigned int    i, j;

//        ASSERT((len % 4) == 0);

        for (i = 0, j = 0; j < len; i++, j += 4) {
            output[j] = (unsigned char) (input[i] & 0xff);
            output[j + 1] = (unsigned char) ((input[i] >> 8) & 0xff);
            output[j + 2] = (unsigned char) ((input[i] >> 16) & 0xff);
            output[j + 3] = (unsigned char) ((input[i] >> 24) & 0xff);
        }
    }

    /*
    * Decodes input (unsigned char) into output (uint32_t). Assumes len is a
    * multiple of 4.
    */
    static void 
    Decode(uint32_t * output, unsigned char *input, unsigned int len)
    {
        unsigned int    i, j;

        for (i = 0, j = 0; j < len; i++, j += 4)
            output[i] = ((uint32_t) input[j]) | (((uint32_t) input[j + 1]) << 8) |
                (((uint32_t) input[j + 2]) << 16) | (((uint32_t) input[j + 3]) << 24);
    }

    /*
    * MD5 basic transformation. Transforms state based on block.
    */
    static void 
    MD5Transform(uint32_t state[4], unsigned char block[64])
    {
        uint32_t           a = state[0], b = state[1], c = state[2], d = state[3],
                        x[16];

        Decode(x, block, 64);

        /* Round 1 */
        FF(a, b, c, d, x[0], S11, 0xd76aa478);    /* 1 */
        FF(d, a, b, c, x[1], S12, 0xe8c7b756);    /* 2 */
        FF(c, d, a, b, x[2], S13, 0x242070db);    /* 3 */
        FF(b, c, d, a, x[3], S14, 0xc1bdceee);    /* 4 */
        FF(a, b, c, d, x[4], S11, 0xf57c0faf);    /* 5 */
        FF(d, a, b, c, x[5], S12, 0x4787c62a);    /* 6 */
        FF(c, d, a, b, x[6], S13, 0xa8304613);    /* 7 */
        FF(b, c, d, a, x[7], S14, 0xfd469501);    /* 8 */
        FF(a, b, c, d, x[8], S11, 0x698098d8);    /* 9 */
        FF(d, a, b, c, x[9], S12, 0x8b44f7af);    /* 10 */
        FF(c, d, a, b, x[10], S13, 0xffff5bb1);    /* 11 */
        FF(b, c, d, a, x[11], S14, 0x895cd7be);    /* 12 */
        FF(a, b, c, d, x[12], S11, 0x6b901122);    /* 13 */
        FF(d, a, b, c, x[13], S12, 0xfd987193);    /* 14 */
        FF(c, d, a, b, x[14], S13, 0xa679438e);    /* 15 */
        FF(b, c, d, a, x[15], S14, 0x49b40821);    /* 16 */

        /* Round 2 */
        GG(a, b, c, d, x[1], S21, 0xf61e2562);    /* 17 */
        GG(d, a, b, c, x[6], S22, 0xc040b340);    /* 18 */
        GG(c, d, a, b, x[11], S23, 0x265e5a51);    /* 19 */
        GG(b, c, d, a, x[0], S24, 0xe9b6c7aa);    /* 20 */
        GG(a, b, c, d, x[5], S21, 0xd62f105d);    /* 21 */
        GG(d, a, b, c, x[10], S22, 0x2441453);    /* 22 */
        GG(c, d, a, b, x[15], S23, 0xd8a1e681);    /* 23 */
        GG(b, c, d, a, x[4], S24, 0xe7d3fbc8);    /* 24 */
        GG(a, b, c, d, x[9], S21, 0x21e1cde6);    /* 25 */
        GG(d, a, b, c, x[14], S22, 0xc33707d6);    /* 26 */
        GG(c, d, a, b, x[3], S23, 0xf4d50d87);    /* 27 */
        GG(b, c, d, a, x[8], S24, 0x455a14ed);    /* 28 */
        GG(a, b, c, d, x[13], S21, 0xa9e3e905);    /* 29 */
        GG(d, a, b, c, x[2], S22, 0xfcefa3f8);    /* 30 */
        GG(c, d, a, b, x[7], S23, 0x676f02d9);    /* 31 */
        GG(b, c, d, a, x[12], S24, 0x8d2a4c8a);    /* 32 */

        /* Round 3 */
        HH(a, b, c, d, x[5], S31, 0xfffa3942);    /* 33 */
        HH(d, a, b, c, x[8], S32, 0x8771f681);    /* 34 */
        HH(c, d, a, b, x[11], S33, 0x6d9d6122);    /* 35 */
        HH(b, c, d, a, x[14], S34, 0xfde5380c);    /* 36 */
        HH(a, b, c, d, x[1], S31, 0xa4beea44);    /* 37 */
        HH(d, a, b, c, x[4], S32, 0x4bdecfa9);    /* 38 */
        HH(c, d, a, b, x[7], S33, 0xf6bb4b60);    /* 39 */
        HH(b, c, d, a, x[10], S34, 0xbebfbc70);    /* 40 */
        HH(a, b, c, d, x[13], S31, 0x289b7ec6);    /* 41 */
        HH(d, a, b, c, x[0], S32, 0xeaa127fa);    /* 42 */
        HH(c, d, a, b, x[3], S33, 0xd4ef3085);    /* 43 */
        HH(b, c, d, a, x[6], S34, 0x4881d05);    /* 44 */
        HH(a, b, c, d, x[9], S31, 0xd9d4d039);    /* 45 */
        HH(d, a, b, c, x[12], S32, 0xe6db99e5);    /* 46 */
        HH(c, d, a, b, x[15], S33, 0x1fa27cf8);    /* 47 */
        HH(b, c, d, a, x[2], S34, 0xc4ac5665);    /* 48 */

        /* Round 4 */
        II(a, b, c, d, x[0], S41, 0xf4292244);    /* 49 */
        II(d, a, b, c, x[7], S42, 0x432aff97);    /* 50 */
        II(c, d, a, b, x[14], S43, 0xab9423a7);    /* 51 */
        II(b, c, d, a, x[5], S44, 0xfc93a039);    /* 52 */
        II(a, b, c, d, x[12], S41, 0x655b59c3);    /* 53 */
        II(d, a, b, c, x[3], S42, 0x8f0ccc92);    /* 54 */
        II(c, d, a, b, x[10], S43, 0xffeff47d);    /* 55 */
        II(b, c, d, a, x[1], S44, 0x85845dd1);    /* 56 */
        II(a, b, c, d, x[8], S41, 0x6fa87e4f);    /* 57 */
        II(d, a, b, c, x[15], S42, 0xfe2ce6e0);    /* 58 */
        II(c, d, a, b, x[6], S43, 0xa3014314);    /* 59 */
        II(b, c, d, a, x[13], S44, 0x4e0811a1);    /* 60 */
        II(a, b, c, d, x[4], S41, 0xf7537e82);    /* 61 */
        II(d, a, b, c, x[11], S42, 0xbd3af235);    /* 62 */
        II(c, d, a, b, x[2], S43, 0x2ad7d2bb);    /* 63 */
        II(b, c, d, a, x[9], S44, 0xeb86d391);    /* 64 */

        state[0] += a;
        state[1] += b;
        state[2] += c;
        state[3] += d;

        /*
        * Zeroize sensitive information.
        */
        memset((unsigned char *) x, 0, sizeof(x));
    }

    /**
    * MD5Init:
    * @context: MD5 context to be initialized.
    * 
    * Initializes MD5 context for the start of message digest computation.
    **/
    void 
    MD5Init(MD5_CTX * context)
    {
        context->count[0] = context->count[1] = 0;
        /* Load magic initialization constants.  */
        context->state[0] = 0x67452301;
        context->state[1] = 0xefcdab89;
        context->state[2] = 0x98badcfe;
        context->state[3] = 0x10325476;
    }

    /**
    * MD5Update:
    * @context: MD5 context to be updated.
    * @input: pointer to data to be fed into MD5 algorithm.
    * @inputLen: size of @input data in bytes.
    * 
    * MD5 block update operation. Continues an MD5 message-digest operation,
    * processing another message block, and updating the context.
    **/

    void 
    MD5Update(MD5_CTX * context, unsigned char *input, unsigned int inputLen)
    {
        unsigned int    i, index, partLen;

        /* Compute number of bytes mod 64 */
        index = (unsigned int) ((context->count[0] >> 3) & 0x3F);

        /* Update number of bits */
        if ((context->count[0] += ((uint32_t) inputLen << 3)) < ((uint32_t) inputLen << 3)) {
            context->count[1]++;
        }
        context->count[1] += ((uint32_t) inputLen >> 29);

        partLen = 64 - index;

        /* Transform as many times as possible.  */
        if (inputLen >= partLen) {
            memcpy((unsigned char *) & context->buffer[index], (unsigned char *) input, partLen);
            MD5Transform(context->state, context->buffer);

            for (i = partLen; i + 63 < inputLen; i += 64) {
                MD5Transform(context->state, &input[i]);
            }
            index = 0;
        } else {
            i = 0;
        }
        /* Buffer remaining input */
        if ((inputLen - i) != 0) {
            memcpy((unsigned char *) & context->buffer[index], (unsigned char *) & input[i], inputLen - i);
        }
    }

    /**
    * MD5Final:
    * @digest: 16-byte buffer to write MD5 checksum.
    * @context: MD5 context to be finalized.
    * 
    * Ends an MD5 message-digest operation, writing the the message
    * digest and zeroing the context.  The context must be initialized
    * with MD5Init() before being used for other MD5 checksum calculations.
    **/

    void 
    MD5Final(unsigned char digest[16], MD5_CTX * context)
    {
        unsigned char   bits[8];
        unsigned int    index, padLen;

        /* Save number of bits */
        Encode(bits, context->count, 8);

        /*
        * Pad out to 56 mod 64.
        */
        index = (unsigned int) ((context->count[0] >> 3) & 0x3f);
        padLen = (index < 56) ? (56 - index) : (120 - index);
        MD5Update(context, PADDING, padLen);

        /* Append length (before padding) */
        MD5Update(context, bits, 8);
        /* Store state in digest */
        Encode(digest, context->state, 16);

        /*
        * Zeroize sensitive information.
        */
        memset((unsigned char *) context, 0, sizeof(*context));
    }

}