C/C++编程：MD5加密

港控/mmm° 2022-09-01 13:52 183阅读 0赞

# 实现 #

// md5.h
    
    #ifndef SQUID_MD5_H
    #define SQUID_MD5_H
    
    #include <stdlib.h>
    
    typedef unsigned int uint32_t;
    typedef unsigned char uint8_t;
    
    typedef struct MD5Context {
        
    	uint32_t buf[4];
    	uint32_t bytes[2];
    	uint32_t in[16];
    } MD5_CTX;
    
    
    void MD5Init(struct MD5Context *context);
    void MD5Update(struct MD5Context *context, const void *buf, unsigned len);
    void MD5Final(uint8_t digest[16], struct MD5Context *context);
    void MD5Transform(uint32_t buf[4], uint32_t const in[16]);
    const char* MD5Key(const char *s, size_t s_len, const char *k, size_t k_len, void* buf, size_t b_len);
    const char* MD5String(const char *s, const char *k, size_t k_len, char* buf, size_t size);
    const char* MD5Key2String(const unsigned char *s, size_t s_len, char* buf, size_t size);
    
    #define MD5_DIGEST_CHARS         16
    
    #endif /* SQUID_MD5_H */

// md5.cpp
    
    /* MS VisualStudio Projects are monolithic, so we need the following
     * #if to exclude the MD5 code from compile process when we are
     * building the SSL support.
     */
    #include <assert.h>
    #include <stdio.h>
    #include "md5.h"
    #include <string.h>
    
    #ifdef WORDS_BIGENDIAN
    void byteSwap(uint32_t * buf, unsigned words)
    {
        
    	uint8_t *p = (uint8_t *) buf;
    
    	do {
        
    		*buf++ = (uint32_t) ((unsigned) p[3] << 8 | p[2]) << 16 |
    			((unsigned) p[1] << 8 | p[0]);
    		p += 4;
    	} while (--words);
    }
    #else
    #define byteSwap(buf,words)
    #endif
    
    /*
     * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
     * initialization constants.
     */
    void MD5Init(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.
     */
    void MD5Update(struct MD5Context *ctx, const void *_buf, unsigned len)
    {
        
    	const uint8_t *buf = (const uint8_t *) _buf;
    	uint32_t 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((uint8_t *) ctx->in + 64 - t, buf, len);
    		return;
    	}
    	/* First chunk is an odd size */
    	memcpy((uint8_t *) 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)
     */
    void MD5Final(unsigned char digest[16], struct MD5Context *ctx)
    {
        
    	int count = ctx->bytes[0] & 0x3f;	/* Number of bytes in ctx->in */
    	uint8_t *p = (uint8_t *) 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 = (uint8_t *) 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 */
    }
    
    /* 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.
     */
    void MD5Transform(uint32_t buf[4], uint32_t const in[16])
    {
        
    	register uint32_t 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;
    }
    
    const char* MD5Key(const char *s, size_t s_len, const char *k, size_t k_len, void* buf, size_t b_len)
    {
        
    	MD5_CTX context;
    	unsigned char digest[16];
    
    	if (b_len != 16) {
        
    		printf("b_len(%d) != 16\n", b_len);
    		assert(0);
    	}
    
    	MD5Init(&context);
    	if (k != NULL && k_len > 0)
    		MD5Update(&context, (const unsigned char *) k, k_len);
    	MD5Update(&context, (const unsigned char*) s, s_len);
    	MD5Final(digest, &context);
    	memcpy(buf, digest, b_len);
    	return ((const char*) buf);
    }
    
    const char* MD5String(const char *s, const char *k, size_t k_len, char* buf, size_t size)
    {
        
    	MD5_CTX context;
    	unsigned char digest[16];
    	char output1[34], *ptr;
    	unsigned int len = (unsigned int) strlen(s);
    	size_t i, n;
    
    	MD5Init(&context);
    	if (k != NULL && k_len > 0)
    		MD5Update(&context, (const unsigned char *) k, k_len);
    	MD5Update(&context, (const unsigned char*) s, len);
    	MD5Final(digest, &context);
    
    	for (i = 0; i < 16; i++) {
        
    		sprintf(&(output1[2 * i]), "%02x", (unsigned char) digest[i]);
    		sprintf(&(output1[2 * i + 1]), "%02x", (unsigned char) (digest[i] << 4));
    	}
    
    	ptr = buf;
    	size--; /* left one byte for '\0' */
    	n = size > 32 ? 32 : size;
    
    	for(i = 0; i < n; i++)
    		*ptr++ = output1[i];
    	*ptr = '\0';
    
    	return (buf);
    }
    
    const char* MD5Key2String(const unsigned char *s, size_t s_len, char* buf, size_t size)
    {
        
    	size_t i, n;
    	char output1[34], *ptr;
    	unsigned char digest[16];
    
    	if (s_len != 16) {
        
    		printf("s_len(%d) != 16\n", s_len);
    		assert(0);
    	}
    	if (size < 32) {
        
    		printf("size(%d) < 32\n", size);
    		assert(0);
    	}
    	memcpy(digest, s, 16);
    
    	for (i = 0; i < 16; i++) {
        
    		sprintf(&(output1[2 * i]), "%02x", (unsigned char) digest[i]);
    		sprintf(&(output1[2 * i + 1]), "%02x", (unsigned char) (digest[i] << 4));
    	}
    
    	ptr = buf;
    	size--; /* left one byte for '\0' */
    	n = size > 32 ? 32 : size;
    
    	for(i = 0; i < n; i++)
    		*ptr++ = output1[i];
    	*ptr = '\0';
    
    	return (buf);
    }

# 使用 #

## 使用一 ##

#include <stdio.h>
    #include <cstring>
    #include "md5.h"
    
    
    
    int main ()
    {
        
    
    
        MD5_CTX md5;
        MD5Init(&md5);                         //初始化用于md5加密的结构
    
        unsigned char encrypt[200] = {
        "hello"};     //存放于加密的信息
        unsigned char decrypt[17];       //存放加密后的结果
    
    
        MD5Update(&md5,encrypt,strlen((char *)encrypt));   //对欲加密的字符进行加密
        MD5Final(decrypt,&md5);                                            //获得最终结果
    
        printf("加密前:%s\n加密后:",encrypt);
    
        for(int i=0;i<16;i++)
            printf("%2x",decrypt[i]);
    
    
        return 0;
    }

## 使用二 ##

#include <stdio.h>
    #include <cstring>
    #include "md5.h"
    
    int main ()
    {
        
        const char* s = "中国人民银行！";
        const char* key = "";
        char  buf2[33];
        
        MD5String(s, key, strlen(key), buf2, sizeof(buf2));
        printf(" md5: %s\r\n", buf2);
        
        return 0;
    }