md5算法(加密)

算法实现：

/* Constants for MD5Transform routine */ enum { S11 = 7, S12 = 12, S13 = 17, S14 = 22, S21 = 5, S22 = 9, S23 = 14, S24 = 20, S31 = 4, S32 = 11, S33 = 16, S34 = 23, S41 = 6, S42 = 10, S43 = 15, S44 = 21 }; static void encode(unsigned char *, const unsigned long *, const unsigned); static void decode(unsigned long *, const unsigned char *, const unsigned); static void transform(unsigned long state[4], const unsigned char block[64]); 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 rotates x left n bits */ #define ROTATE(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) + (unsigned long)(ac); / (a) = ROTATE ((a), (s)); / (a) += (b); / } #define GG(a, b, c, d, x, s, ac) { / (a) += G ((b), (c), (d)) + (x) + (unsigned long)(ac); / (a) = ROTATE ((a), (s)); / (a) += (b); / } #define HH(a, b, c, d, x, s, ac) { / (a) += H ((b), (c), (d)) + (x) + (unsigned long)(ac); / (a) = ROTATE ((a), (s)); / (a) += (b); / } #define II(a, b, c, d, x, s, ac) { / (a) += I ((b), (c), (d)) + (x) + (unsigned long)(ac); / (a) = ROTATE ((a), (s)); / (a) += (b); / } static void encode(unsigned char *output, const unsigned long *input, const unsigned len) { unsigned i, j; 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); } } static void decode(unsigned long *output, const unsigned char *input, const unsigned len) { unsigned i, j; for (i = 0, j = 0; j < len; i++, j += 4) { output[i] = ((unsigned long)input[j]) | (((unsigned long)input[j+1]) << 8) | (((unsigned long)input[j+2]) << 16) | (((unsigned long)input[j+3]) << 24); } } static void transform(unsigned long state[4], const unsigned char block[64]) { unsigned long a = state[0]; unsigned long b = state[1]; unsigned long c = state[2]; unsigned long d = state[3]; unsigned long 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(x, 0, sizeof (x)); } /* MD5 initialization. Begins an MD5 operation, writing a new context. */ void fz_md5init(fz_md5 *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; } /* MD5 block update operation. Continues an MD5 message-digest operation, * processing another message block, and updating the context. */ void fz_md5update(fz_md5 *context, const unsigned char *input, const unsigned inlen) { unsigned i, index, partlen; /* Compute number of bytes mod 64 */ index = (unsigned)((context->count[0] >> 3) & 0x3F); /* Update number of bits */ context->count[0] += (unsigned long) inlen << 3; if (context->count[0] < (unsigned long) inlen << 3) context->count[1] ++; context->count[1] += (unsigned long) inlen >> 29; partlen = 64 - index; /* Transform as many times as possible. */ if (inlen >= partlen) { memcpy(context->buffer + index, input, partlen); transform(context->state, context->buffer); for (i = partlen; i + 63 < inlen; i += 64) transform(context->state, input + i); index = 0; } else { i = 0; } /* Buffer remaining input */ memcpy(context->buffer + index, input + i, inlen - i); } /* MD5 finalization. Ends an MD5 message-digest operation, writing the * the message digest and zeroizing the context. */ void fz_md5final(fz_md5 *context, unsigned char digest[16]) { unsigned char bits[8]; unsigned index, padlen; /* Save number of bits */ encode(bits, context->count, 8); /* Pad out to 56 mod 64 */ index = (unsigned)((context->count[0] >> 3) & 0x3f); padlen = index < 56 ? 56 - index : 120 - index; fz_md5update(context, padding, padlen); /* Append length (before padding) */ fz_md5update(context, bits, 8); /* Store state in digest */ encode(digest, context->state, 16); /* Zeroize sensitive information */ memset(context, 0, sizeof(fz_md5)); }

方法声明：

typedef struct fz_md5_s fz_md5; struct fz_md5_s { unsigned long state[4]; unsigned long count[2]; unsigned char buffer[64]; }; void fz_md5init(fz_md5 *state); void fz_md5update(fz_md5 *state, const unsigned char *input, const unsigned inlen); void fz_md5final(fz_md5 *state, unsigned char digest[16]);

调用示例：

static void voodoo50(unsigned char *buf, int n) { fz_md5 md5; int i; for (i = 0; i < 50; i++) { fz_md5init(&md5); fz_md5update(&md5, buf, n); fz_md5final(&md5, buf); } }