md5.c

/**  
 * support MD5 for PPPoE CHAP mode  
 *   
 * taken from RFC-1321/Appendix A.3  
 * MD5C.C - RSA Data Security, Inc., MD5 message-digest algorithm  
 */   
   
/*  
********************************************************************************  
File Include Section  
********************************************************************************  
*/   
   
#include "md5.h"   
#include "string.h"
   
// Constants for Transform 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   
   
void md5_transform (uint32[4], uint8 [64]);   
void md5_encode    (uint8 *, uint32 *, uint32);   
void md5_decode    (uint32 *, uint8 *, uint32);   
   
uint8 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))))   
           
   
        uint32 FF(uint32 a, uint32 b, uint32 c, uint32 d, uint32 x, uint32 s, uint32 ac)   
        {   
                a += F (b, c, d) + x + (uint32)(ac);   
                a = ROTATE_LEFT (a, s);   
                a += b;   
                return a;   
        }   
        uint32 GG(uint32 a, uint32 b, uint32 c, uint32 d, uint32 x, uint32 s, uint32 ac)   
        {   
                a += G (b, c, d) + x + (uint32)(ac);   
                a = ROTATE_LEFT (a, s);   
                a += b;   
                return a;   
        }   
           
        uint32 HH(uint32 a, uint32 b, uint32 c, uint32 d, uint32 x, uint32 s, uint32 ac)   
        {   
                a += H (b, c, d) + x + (uint32)(ac);   
                a = ROTATE_LEFT (a, s);   
                a += b;   
                return a;   
        }   
   
        uint32 II(uint32 a, uint32 b, uint32 c, uint32 d, uint32 x, uint32 s, uint32 ac)   
        {   
                a += I (b, c, d) + x + (uint32)(ac);   
                a = ROTATE_LEFT (a, s);   
                a += b;   
                return a;   
        }   
   
// md5 initialization. Begins an md5 operation, writing a new context.   
void md5_init(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;   
}   
   
// md5 block update operation. Continues an md5 message-digest operation,   
// processing another message block, and updating the context.   
void md5_update(md5_ctx * context, uint8 *input, uint32 inputLen)   
{   
        uint32 i, index, partLen;   
           
        // Compute number of bytes mod 64   
        index = (uint32)((context->count[0] >> 3) & 0x3F);   
           
        // Update number of bits   
        if ((context->count[0] += ((uint32)inputLen << 3)) < ((uint32)inputLen << 3))   
                context->count[1]++;   
        context->count[1] += ((uint32)inputLen >> 29);   
           
        partLen = 64 - index;   
           
        // md5_Transform as many times as possible.   
        if (inputLen >= partLen)   
        {   
                memcpy(&context->buffer[index], input, partLen);   
                md5_transform(context->state, context->buffer);   
           
                for (i = partLen; i + 63 < inputLen; i += 64)   
                        md5_transform(context->state, &input[i]);   
                index = 0;   
        }   
        else   
                i = 0;   
           
        // Buffer remaining input   
        memcpy(&context->buffer[index], &input[i], inputLen - i);   
}   
   
// md5 finalization. Ends an md5 message-digest operation, writing the   
// message digest and zeroizing the context.   
void md5_final(uint8 digest[16], md5_ctx *context)   
{   
        uint8  bits[8];   
        uint32 index, padLen;   
           
        // Save number of bits   
        md5_encode(bits, context->count, 8);   
           
        // Pad out to 56 mod 64.   
        index  = (uint32)((context->count[0] >> 3) & 0x3f);   
        padLen = (index < 56) ? (56 - index) : (120 - index);   
        md5_update(context, padding, padLen);   
           
        // Append length (before padding)   
        md5_update(context, bits, 8);   
        // Store state in digest   
        md5_encode(digest, context->state, 16);   
           
        // Zeroize sensitive information.   
        memset((void*)context,0,sizeof(*context));   
}   
   
// md5 basic transformation. Transforms state based on block.   
void md5_transform(uint32 state[4], uint8 block[64])   
{   
        uint32 a = state[0];   
        uint32 b = state[1];   
        uint32 c = state[2];   
        uint32 d = state[3];   
        uint32 x[16];   
           
        md5_decode(x, block, 64);   
   
        // Round 1   
        a = FF(a, b, c, d, x[0],  S11, 0xd76aa478);     // 1   
        d = FF(d, a, b, c, x[1],  S12, 0xe8c7b756); // 2   
        c = FF(c, d, a, b, x[2],  S13, 0x242070db); // 3   
        b = FF(b, c, d, a, x[3],  S14, 0xc1bdceee); // 4   
        a = FF(a, b, c, d, x[4],  S11, 0xf57c0faf); // 5   
        d = FF(d, a, b, c, x[5],  S12, 0x4787c62a); // 6   
        c = FF(c, d, a, b, x[6],  S13, 0xa8304613); // 7   
        b = FF(b, c, d, a, x[7],  S14, 0xfd469501); // 8   
        a = FF(a, b, c, d, x[8],  S11, 0x698098d8); // 9   
        d = FF(d, a, b, c, x[9],  S12, 0x8b44f7af); // 10   
        c = FF(c, d, a, b, x[10], S13, 0xffff5bb1); // 11   
        b = FF(b, c, d, a, x[11], S14, 0x895cd7be); // 12   
        a = FF(a, b, c, d, x[12], S11, 0x6b901122); // 13   
        d = FF(d, a, b, c, x[13], S12, 0xfd987193); // 14   
        c = FF(c, d, a, b, x[14], S13, 0xa679438e); // 15   
        b = FF(b, c, d, a, x[15], S14, 0x49b40821); // 16   
   
        // Round 2   
        a = GG(a, b, c, d, x[1],  S21, 0xf61e2562); // 17   
        d = GG(d, a, b, c, x[6],  S22, 0xc040b340); // 18   
        c = GG(c, d, a, b, x[11], S23, 0x265e5a51); // 19   
        b = GG(b, c, d, a, x[0],  S24, 0xe9b6c7aa); // 20   
        a = GG(a, b, c, d, x[5],  S21, 0xd62f105d); // 21   
        d = GG(d, a, b, c, x[10], S22, 0x2441453);  // 22   
        c = GG(c, d, a, b, x[15], S23, 0xd8a1e681); // 23   
        b = GG(b, c, d, a, x[4],  S24, 0xe7d3fbc8); // 24   
        a = GG(a, b, c, d, x[9],  S21, 0x21e1cde6); // 25   
        d = GG(d, a, b, c, x[14], S22, 0xc33707d6); // 26   
        c = GG(c, d, a, b, x[3],  S23, 0xf4d50d87); // 27   
        b = GG(b, c, d, a, x[8],  S24, 0x455a14ed); // 28   
        a = GG(a, b, c, d, x[13], S21, 0xa9e3e905); // 29   
        d = GG(d, a, b, c, x[2],  S22, 0xfcefa3f8); // 30   
        c = GG(c, d, a, b, x[7],  S23, 0x676f02d9); // 31   
        b = GG(b, c, d, a, x[12], S24, 0x8d2a4c8a); // 32   
           
        // Round 3   
        a = HH(a, b, c, d, x[5],  S31, 0xfffa3942); // 33   
        d = HH(d, a, b, c, x[8],  S32, 0x8771f681); // 34   
        c = HH(c, d, a, b, x[11], S33, 0x6d9d6122); // 35   
        b = HH(b, c, d, a, x[14], S34, 0xfde5380c); // 36   
        a = HH(a, b, c, d, x[1],  S31, 0xa4beea44); // 37   
        d = HH(d, a, b, c, x[4],  S32, 0x4bdecfa9); // 38   
        c = HH(c, d, a, b, x[7],  S33, 0xf6bb4b60); // 39   
        b = HH(b, c, d, a, x[10], S34, 0xbebfbc70); // 40   
        a = HH(a, b, c, d, x[13], S31, 0x289b7ec6); // 41   
        d = HH(d, a, b, c, x[0],  S32, 0xeaa127fa); // 42   
        c = HH(c, d, a, b, x[3],  S33, 0xd4ef3085); // 43   
        b = HH(b, c, d, a, x[6],  S34, 0x4881d05);  // 44   
        a = HH(a, b, c, d, x[9],  S31, 0xd9d4d039); // 45   
        d = HH(d, a, b, c, x[12], S32, 0xe6db99e5); // 46   
        c = HH(c, d, a, b, x[15], S33, 0x1fa27cf8); // 47   
        b = HH(b, c, d, a, x[2],  S34, 0xc4ac5665); // 48   
   
        // Round 4   
        a = II(a, b, c, d, x[0],  S41, 0xf4292244); // 49   
        d = II(d, a, b, c, x[7],  S42, 0x432aff97); // 50   
        c = II(c, d, a, b, x[14], S43, 0xab9423a7); // 51   
        b = II(b, c, d, a, x[5],  S44, 0xfc93a039); // 52   
        a = II(a, b, c, d, x[12], S41, 0x655b59c3); // 53   
        d = II(d, a, b, c, x[3],  S42, 0x8f0ccc92); // 54   
        c = II(c, d, a, b, x[10], S43, 0xffeff47d); // 55   
        b = II(b, c, d, a, x[1],  S44, 0x85845dd1); // 56   
        a = II(a, b, c, d, x[8],  S41, 0x6fa87e4f); // 57   
        d = II(d, a, b, c, x[15], S42, 0xfe2ce6e0); // 58   
        c = II(c, d, a, b, x[6],  S43, 0xa3014314); // 59   
        b = II(b, c, d, a, x[13], S44, 0x4e0811a1); // 60   
        a = II(a, b, c, d, x[4],  S41, 0xf7537e82); // 61   
        d = II(d, a, b, c, x[11], S42, 0xbd3af235); // 62   
        c = II(c, d, a, b, x[2],  S43, 0x2ad7d2bb); // 63   
        b = 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));   
}   
   
// Encodes input (uint32) into output (uint8). Assumes len is a   
// multiple of 4.   
void md5_encode(uint8 *output, uint32 *input, uint32 len)   
{   
        uint32 i, j;   
           
        for (i = 0, j = 0; j < len; i++, j += 4)   
        {   
                output[j]     = (uint8)(input[i] & 0xff);   
                output[j + 1] = (uint8)((input[i] >> 8) & 0xff);   
                output[j + 2] = (uint8)((input[i] >> 16) & 0xff);   
                output[j + 3] = (uint8)((input[i] >> 24) & 0xff);   
        }   
}   
   
// Decodes input (uint8) into output (uint32). Assumes len is a   
// multiple of 4.   
void md5_decode(uint32 *output, uint8 *input, uint32 len)   
{   
        uint32 i, j;   
        for (i = 0, j = 0; j < len; i++, j += 4)   
                output[i] = ((uint32) input[j]) | (((uint32) input[j + 1]) << 8) |   
                                (((uint32)input[j + 2]) << 16) | (((uint32)input[j + 3]) << 24);   
}