MD5

摘自QT：qtbase\src\3rdparty\md5\md5.h及cpp

/* * This is the header file for the MD5 message-digest algorithm. * The algorithm is due to Ron Rivest.  This code was * written by Colin Plumb in 1993, no copyright is claimed. * This code is in the public domain; do with it what you wish. * * Equivalent code is available from RSA Data Security, Inc. * This code has been tested against that, and is equivalent, * except that you don't need to include two pages of legalese * with every copy. * * To compute the message digest of a chunk of bytes, declare an * MD5Context structure, pass it to MD5Init, call MD5Update as * needed on buffers full of bytes, and then call MD5Final, which * will fill a supplied 16-byte array with the digest. * * Changed so as no longer to depend on Colin Plumb's `usual.h' * header definitions; now uses stuff from dpkg's config.h *  - Ian Jackson <[e-mail]>. * Still in the public domain. */#ifndef MD5_H#define MD5_H#include <qglobal.h>#include <qbytearray.h>#include <qstring.h>QT_BEGIN_NAMESPACEtypedef unsigned char md5byte;typedef quint32 UWORD32;struct MD5Context {UWORD32 buf[4];UWORD32 bytes[2];UWORD32 in[16];};static void MD5Init(struct MD5Context *context);static void MD5Update(struct MD5Context *context, md5byte const *buf, unsigned len);static void MD5Final(struct MD5Context *context, unsigned char digest[16]);static void MD5Transform(UWORD32 buf[4], UWORD32 const in[16]);QT_END_NAMESPACE#endif /* !MD5_H */

实现部分:

/* * This code implements the MD5 message-digest algorithm. * The algorithm is due to Ron Rivest.  This code was * written by Colin Plumb in 1993, no copyright is claimed. * This code is in the public domain; do with it what you wish. * * Equivalent code is available from RSA Data Security, Inc. * This code has been tested against that, and is equivalent, * except that you don't need to include two pages of legalese * with every copy. * * To compute the message digest of a chunk of bytes, declare an * MD5Context structure, pass it to MD5Init, call MD5Update as * needed on buffers full of bytes, and then call MD5Final, which * will fill a supplied 16-byte array with the digest. * * Changed so as no longer to depend on Colin Plumb's `usual.h' header * definitions; now uses stuff from dpkg's config.h. *  - Ian Jackson <[e-mail]>. * Still in the public domain. */#include <string.h>/* for memcpy() */#ifndef _WIN32_WCE#include <sys/types.h>/* for stupid systems */#else#include <windef.h>#include <types.h>#endif#include "md5.h"QT_BEGIN_NAMESPACEstatic voidbyteSwap(UWORD32 *buf, unsigned words){        const quint32 byteOrderTest = 0x1;        if (((char *)&byteOrderTest)[0] == 0) {            md5byte *p = (md5byte *)buf;            do {                *buf++ = (UWORD32)((unsigned)p[3] << 8 | p[2]) << 16 |                    ((unsigned)p[1] << 8 | p[0]);                p += 4;            } while (--words);        }}/* * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious * initialization constants. */static voidMD5Init(struct MD5Context *ctx){ctx->buf[0] = 0x67452301;ctx->buf[1] = 0xefcdab89;ctx->buf[2] = 0x98badcfe;ctx->buf[3] = 0x10325476;ctx->bytes[0] = 0;ctx->bytes[1] = 0;}/* * Update context to reflect the concatenation of another buffer full * of bytes. */static voidMD5Update(struct MD5Context *ctx, md5byte const *buf, unsigned len){UWORD32 t;/* Update byte count */t = ctx->bytes[0];if ((ctx->bytes[0] = t + len) < t)ctx->bytes[1]++;/* Carry from low to high */t = 64 - (t & 0x3f);/* Space available in ctx->in (at least 1) */if (t > len) {memcpy((md5byte *)ctx->in + 64 - t, buf, len);return;}/* First chunk is an odd size */memcpy((md5byte *)ctx->in + 64 - t, buf, t);byteSwap(ctx->in, 16);MD5Transform(ctx->buf, ctx->in);buf += t;len -= t;/* Process data in 64-byte chunks */while (len >= 64) {memcpy(ctx->in, buf, 64);byteSwap(ctx->in, 16);MD5Transform(ctx->buf, ctx->in);buf += 64;len -= 64;}/* Handle any remaining bytes of data. */memcpy(ctx->in, buf, len);}/* * Final wrapup - pad to 64-byte boundary with the bit pattern  * 1 0* (64-bit count of bits processed, MSB-first) */static voidMD5Final(struct MD5Context *ctx, md5byte digest[16]){int count = ctx->bytes[0] & 0x3f;/* Number of bytes in ctx->in */md5byte *p = (md5byte *)ctx->in + count;/* Set the first char of padding to 0x80.  There is always room. */*p++ = 0x80;/* Bytes of padding needed to make 56 bytes (-8..55) */count = 56 - 1 - count;if (count < 0) {/* Padding forces an extra block */memset(p, 0, count + 8);byteSwap(ctx->in, 16);MD5Transform(ctx->buf, ctx->in);p = (md5byte *)ctx->in;count = 56;}memset(p, 0, count);byteSwap(ctx->in, 14);/* Append length in bits and transform */ctx->in[14] = ctx->bytes[0] << 3;ctx->in[15] = ctx->bytes[1] << 3 | ctx->bytes[0] >> 29;MD5Transform(ctx->buf, ctx->in);byteSwap(ctx->buf, 4);memcpy(digest, ctx->buf, 16);memset(ctx, 0, sizeof(*ctx));/* In case it's sensitive */}#ifndef ASM_MD5/* The four core functions - F1 is optimized somewhat *//* #define F1(x, y, z) (x & y | ~x & z) */#define F1(x, y, z) (z ^ (x & (y ^ z)))#define F2(x, y, z) F1(z, x, y)#define F3(x, y, z) (x ^ y ^ z)#define F4(x, y, z) (y ^ (x | ~z))/* This is the central step in the MD5 algorithm. */#define MD5STEP(f,w,x,y,z,in,s) \ (w += f(x,y,z) + in, w = (w<<s | w>>(32-s)) + x)/* * The core of the MD5 algorithm, this alters an existing MD5 hash to * reflect the addition of 16 longwords of new data.  MD5Update blocks * the data and converts bytes into longwords for this routine. */static voidMD5Transform(UWORD32 buf[4], UWORD32 const in[16]){register UWORD32 a, b, c, d;a = buf[0];b = buf[1];c = buf[2];d = buf[3];MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);buf[0] += a;buf[1] += b;buf[2] += c;buf[3] += d;}#endifQT_END_NAMESPACE

另外MongDB中也有C++封装