Linux 下MD5的C語言實現

編者注：經測試，此方法得到的md5碼不正確，但如果用於私有加密還是可以使用

源文件如下：

//md5.h

1. #ifndef MD5_H
2. #define MD5_H
4. #ifdef __alpha
5. typedef unsigned int uint32;
6. #else
7. typedef unsigned long uint32;
8. #endif
10. struct MD5Context {
11. uint32 buf[4];
12. uint32 bits[2];
13. unsigned char in[64];
14. };
16. extern void MD5Init();
17. extern void MD5Update();
18. extern void MD5Final();
19. extern void MD5Transform();
21. /*
22. * This is needed to make RSAREF happy on some MS-DOS compilers.
23. */
24. typedef struct MD5Context MD5_CTX;
26. #endif /* !MD5_H */

//md5.c

1. /*
2. * This code implements the MD5 message-digest algorithm.
3. * The algorithm is due to Ron Rivest. This code was
4. * written by Colin Plumb in 1993, no copyright is claimed.
5. * This code is in the public domain; do with it what you wish.
6. *
7. * Equivalent code is available from RSA Data Security, Inc.
8. * This code has been tested against that, and is equivalent,
9. * except that you don't need to include two pages of legalese
10. * with every copy.
11. *
12. * To compute the message digest of a chunk of bytes, declare an
13. * MD5Context structure, pass it to MD5Init, call MD5Update as
14. * needed on buffers full of bytes, and then call MD5Final, which
15. * will fill a supplied 16-byte array with the digest.
16. */
18. /* Brutally hacked by John Walker back from ANSI C to K&R (no
19. prototypes) to maintain the tradition that Netfone will compile
20. with Sun's original "cc". */
22. #include <memory.h> /* for memcpy() */
23. #include "md5.h"
25. #ifdef sgi
26. #define HIGHFIRST
27. #endif
29. #ifdef sun
30. #define HIGHFIRST
31. #endif
33. #ifndef HIGHFIRST
34. #define byteReverse(buf, len) /* Nothing */
35. #else
36. /*
37. * Note: this code is harmless on little-endian machines.
38. */
39. void byteReverse(buf, longs)
40. unsigned char *buf; unsigned longs;
41. {
42. uint32 t;
43. do {
44. t = (uint32) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
45. ((unsigned) buf[1] << 8 | buf[0]);
46. *(uint32 *) buf = t;
47. buf += 4;
48. } while (--longs);
49. }
50. #endif
52. /*
53. * Start MD5 accumulation. Set bit count to 0 and buffer to mysterious
54. * initialization constants.
55. */
56. void MD5Init(ctx)
57. struct MD5Context *ctx;
58. {
59. ctx->buf[0] = 0x67452301;
60. ctx->buf[1] = 0xefcdab89;
61. ctx->buf[2] = 0x98badcfe;
62. ctx->buf[3] = 0x10325476;
64. ctx->bits[0] = 0;
65. ctx->bits[1] = 0;
66. }
68. /*
69. * Update context to reflect the concatenation of another buffer full
70. * of bytes.
71. */
72. void MD5Update(ctx, buf, len)
73. struct MD5Context *ctx; unsigned char *buf; unsigned len;
74. {
75. uint32 t;
77. /* Update bitcount */
79. t = ctx->bits[0];
80. if ((ctx->bits[0] = t + ((uint32) len << 3)) < t)
81. ctx->bits[1]++; /* Carry from low to high */
82. ctx->bits[1] += len >> 29;
84. t = (t >> 3) & 0x3f; /* Bytes already in shsInfo->data */
86. /* Handle any leading odd-sized chunks */
88. if (t) {
89. unsigned char *p = (unsigned char *) ctx->in + t;
91. t = 64 - t;
92. if (len < t) {
93. memcpy(p, buf, len);
94. return;
95. }
96. memcpy(p, buf, t);
97. byteReverse(ctx->in, 16);
98. MD5Transform(ctx->buf, (uint32 *) ctx->in);
99. buf += t;
100. len -= t;
101. }
102. /* Process data in 64-byte chunks */
104. while (len >= 64) {
105. memcpy(ctx->in, buf, 64);
106. byteReverse(ctx->in, 16);
107. MD5Transform(ctx->buf, (uint32 *) ctx->in);
108. buf += 64;
109. len -= 64;
110. }
112. /* Handle any remaining bytes of data. */
114. memcpy(ctx->in, buf, len);
115. }
117. /*
118. * Final wrapup - pad to 64-byte boundary with the bit pattern
119. * 1 0* (64-bit count of bits processed, MSB-first)
120. */
121. void MD5Final(digest, ctx)
122. unsigned char digest[16]; struct MD5Context *ctx;
123. {
124. unsigned count;
125. unsigned char *p;
127. /* Compute number of bytes mod 64 */
128. count = (ctx->bits[0] >> 3) & 0x3F;
130. /* Set the first char of padding to 0x80. This is safe since there is
131. always at least one byte free */
132. p = ctx->in + count;
133. *p++ = 0x80;
135. /* Bytes of padding needed to make 64 bytes */
136. count = 64 - 1 - count;
138. /* Pad out to 56 mod 64 */
139. if (count < 8) {
140. /* Two lots of padding: Pad the first block to 64 bytes */
141. memset(p, 0, count);
142. byteReverse(ctx->in, 16);
143. MD5Transform(ctx->buf, (uint32 *) ctx->in);
145. /* Now fill the next block with 56 bytes */
146. memset(ctx->in, 0, 56);
147. } else {
148. /* Pad block to 56 bytes */
149. memset(p, 0, count - 8);
150. }
151. byteReverse(ctx->in, 14);
153. /* Append length in bits and transform */
154. ((uint32 *) ctx->in)[14] = ctx->bits[0];
155. ((uint32 *) ctx->in)[15] = ctx->bits[1];
157. MD5Transform(ctx->buf, (uint32 *) ctx->in);
158. byteReverse((unsigned char *) ctx->buf, 4);
159. memcpy(digest, ctx->buf, 16);
160. memset(ctx, 0, sizeof(ctx)); /* In case it's sensitive */
161. }
164. /* The four core functions - F1 is optimized somewhat */
166. /* #define F1(x, y, z) (x & y | ~x & z) */
167. #define F1(x, y, z) (z ^ (x & (y ^ z)))
168. #define F2(x, y, z) F1(z, x, y)
169. #define F3(x, y, z) (x ^ y ^ z)
170. #define F4(x, y, z) (y ^ (x | ~z))
172. /* This is the central step in the MD5 algorithm. */
173. #define MD5STEP(f, w, x, y, z, data, s) \
174. ( w += f(x, y, z) + data, w = w<<s | w>>(32-s), w += x )
176. /*
177. * The core of the MD5 algorithm, this alters an existing MD5 hash to
178. * reflect the addition of 16 longwords of new data. MD5Update blocks
179. * the data and converts bytes into longwords for this routine.
180. */
181. void MD5Transform(buf, in)
182. uint32 buf[4]; uint32 in[16];
183. {
184. register uint32 a, b, c, d;
186. a = buf[0];
187. b = buf[1];
188. c = buf[2];
189. d = buf[3];
191. MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
192. MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
193. MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
194. MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
195. MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
196. MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
197. MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
198. MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
199. MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
200. MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
201. MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
202. MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
203. MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
204. MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
205. MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
206. MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
208. MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
209. MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
210. MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
211. MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
212. MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
213. MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
214. MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
215. MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
216. MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
217. MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
218. MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
219. MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
220. MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
221. MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
222. MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
223. MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
225. MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
226. MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
227. MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
228. MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
229. MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
230. MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
231. MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
232. MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
233. MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
234. MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
235. MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
236. MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
237. MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
238. MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
239. MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
240. MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
242. MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
243. MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
244. MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
245. MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
246. MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
247. MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
248. MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
249. MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
250. MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
251. MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
252. MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
253. MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
254. MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
255. MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
256. MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
257. MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
259. buf[0] += a;
260. buf[1] += b;
261. buf[2] += c;
262. buf[3] += d;
263. }

//實例 main.c

1. #include <stdio.h>
2. #include <string.h>
4. #include "md5.h"
6. int main( int argc, char **argv )
7. {
8. struct MD5Context md5c;
9. char *s;
10. unsigned char ss[16];
11. char buf[33]={'\0'};
12. char tmp[3]={'\0'};
13. int i;
15. if( 2!=argc )
16. {
17. printf( "usage :\tmd5 <string>\n" );
18. return 1;
19. }
20. s = argv[1];
22. MD5Init( &md5c );
23. MD5Update( &md5c, s, strlen(s) );
24. MD5Final( ss, &md5c );
26. for( i=0; i<16; i++ ){
27. sprintf(tmp,"%02X", ss[i] );
28. strcat(buf,tmp);
29. }
30. printf("%s",buf);
31. printf( "\t%s\n", s );
33. return 0;
34. }

//Makefile

1. main:main.o
2. gcc main.o md5.o -o main
3. main.o:main.c
4. gcc -c main.c
5. md5.o:md5.c md5.h
6. gcc -c md5.c
7. clean:
8. rm *.o

編譯後，運行時加入參數，即要編碼的字符串
$ ./main 123
結果如下：
202CB962AC59075B964B07152D234B70 123