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/*
    Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
    rights reserved.

    RSA Data Security, Inc. makes no representations concerning either
    the merchantability of this software or the suitability of this
    software for any particular purpose. It is provided "as is"
    without express or implied warranty of any kind.

    License to copy and use this software is granted provided that it
    is identified as the "RSA Data Security, Inc. MD5 Message-Digest
    Algorithm" in all material mentioning or referencing this software
    or this function.

    License is also granted to make and use derivative works provided
    that such works are identified as "derived from the RSA Data
    Security, Inc. MD5 Message-Digest Algorithm" in all material
    mentioning or referencing the derived work.

    These notices must be retained in any copies of any part of this
    documentation and/or software.
*/

#include "qtmd5.h"

typedef unsigned char *POINTER;
typedef unsigned short int UINT2;
typedef unsigned long int UINT4;

typedef struct {
    UINT4 state[4];            // state(ABCD)
    UINT4 count[2];            // number of bits, modulo 2^64(lsb first)
    unsigned char buffer[64];  // input buffer
} MD5_CTX;

static void MD5Init(MD5_CTX *);
static void MD5Update(MD5_CTX *, unsigned char *, unsigned int);
static void MD5Final(unsigned char [16], MD5_CTX *);
static void MD5Transform(UINT4[4], unsigned char[64]);
static void Encode(unsigned char *, UINT4 *, unsigned int);
static void Decode(UINT4 *, unsigned char *, unsigned int);
static void MD5_memset(POINTER, int, unsigned int);
static void MD5_memcpy(POINTER output,POINTER input,unsigned int len);

// 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 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.
static inline UINT4 F(UINT4 x, UINT4 y, UINT4 z)
{
    return (x & y) |((~x) & z);
}

static inline UINT4 G(UINT4 x, UINT4 y, UINT4 z)
{
    return (x & z) |(y &(~z));
}

static inline UINT4 H(UINT4 x, UINT4 y, UINT4 z)
{
    return x ^ y ^ z;
}

static inline UINT4 I(UINT4 x, UINT4 y, UINT4 z)
{
    return y ^(x |(~z));
}

static inline UINT4 rotateLeft(UINT4 x, UINT4 n)
{
    return (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.
static inline void FF(UINT4 &a, UINT4 b, UINT4 c, UINT4 d, UINT4 x, UINT4 s, UINT4 ac)
{
    a += F(b, c, d) + x + ac;
    a = rotateLeft(a, s);
    a += b;
}

static inline void GG(UINT4 &a, UINT4 b, UINT4 c, UINT4 d, UINT4 x, UINT4 s, UINT4 ac)
{
    a += G(b, c, d) + x +(UINT4)(ac);
    a = rotateLeft(a, s);
    a += b;
}

static inline void HH(UINT4 &a, UINT4 b, UINT4 c, UINT4 d, UINT4 x, UINT4 s, UINT4 ac)
{
    a += H(b, c, d) + x +(UINT4)(ac);
    a = rotateLeft(a, s);
    a += b;
}

static inline void II(UINT4 &a, UINT4 b, UINT4 c, UINT4 d, UINT4 x, UINT4 s, UINT4 ac)
{
    a += I(b, c, d) + x +(UINT4)(ac);
    a = rotateLeft(a, s);
    a += b;
}

// MD5 initialization. Begins an MD5 operation, writing a new context.
static void MD5Init(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.
static void MD5Update(MD5_CTX *context, unsigned char *input, unsigned int inputLen)
{
    unsigned int i, index, partLen;
    // Compute number of bytes mod 64
    index =(unsigned int)((context->count[0] >> 3) & 0x3F);

    // Update number of bits
    if ((context->count[0] +=((UINT4)inputLen << 3)) <((UINT4)inputLen << 3))
        context->count[1]++;

    context->count[1] +=((UINT4)inputLen >> 29);
    partLen = 64 - index;

    // Transform as many times as possible.
    if (inputLen >= partLen) {
        MD5_memcpy((POINTER)&context->buffer[index],(POINTER)input, partLen);
        MD5Transform(context->state, context->buffer);
        for (i = partLen; i + 63 < inputLen; i += 64)
            MD5Transform(context->state, &input[i]);
        index = 0;
    } else {
        i = 0;
    }

    // Buffer remaining input
    MD5_memcpy((POINTER)&context->buffer[index],(POINTER)&input[i],
               inputLen-i);
}

// MD5 finalization. Ends an MD5 message-digest operation, writing the
// the message digest and zeroizing the context.
static void MD5Final(unsigned char digest[16], MD5_CTX *context)
{
    unsigned char bits[8];
    unsigned int index, padLen;

    // Save number of bits
    Encode(bits, context->count, 8);

    // Pad out to 56 mod 64.
    index =(unsigned int)((context->count[0] >> 3) & 0x3f);
    padLen =(index < 56) ?(56 - index) :(120 - index);
    MD5Update(context, PADDING, padLen);

    // Append length(before padding)
    MD5Update(context, bits, 8);

    // Store state in digest
    Encode(digest, context->state, 16);

    // Zeroize sensitive information.
    MD5_memset((POINTER)context, 0, sizeof(*context));
}

// MD5 basic transformation. Transforms state based on block.
static void MD5Transform(UINT4 state[4], unsigned char block[64])
{
    UINT4 a = state[0], b = state[1], c = state[2], d = state[3], 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.
    MD5_memset((POINTER)x, 0, sizeof(x));
}

// Encodes input(UINT4) into output(unsigned char). Assumes len is a
// multiple of 4.
static void Encode(unsigned char *output, UINT4 *input, unsigned int len)
{
    unsigned int 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);
    }
}

// Decodes input(unsigned char) into output(UINT4). Assumes len is a
// multiple of 4.
static void Decode(UINT4 *output, unsigned char *input, unsigned int len)
{
    unsigned int i, j;
    for (i = 0, j = 0; j < len; i++, j += 4)
        output[i] =((UINT4)input[j]) |(((UINT4)input[j+1]) << 8) |
                  (((UINT4)input[j+2]) << 16) |(((UINT4)input[j+3]) << 24);
}

// Note: Replace "for loop" with standard memset if possible.
static void MD5_memset(POINTER output, int value, unsigned int len)
{
    unsigned int i;
    for (i = 0; i < len; i++)
        ((char *)output)[i] =(char)value;
}

// Note: Replace "for loop" with standard memcpy if possible.
static void MD5_memcpy(POINTER output,POINTER input,unsigned int len)
{
    unsigned int i;
    for (i = 0; i < len; i++)
        output[i] = input[i];
}

void qtMD5(const QByteArray &src, unsigned char *digest)
{
    MD5_CTX context;

    MD5Init(&context);
    MD5Update(&context, (unsigned char *) src.data(), src.size());
    MD5Final(digest, &context);
}

QString qtMD5(const QByteArray &src)
{
    unsigned char digest[16];
    qtMD5(src, digest);

    QString output, tmp;
    for (int i = 0; i < 16; ++i)
        output += tmp.sprintf("%02x", digest[i]);
    return output;
}
