/* Copyright 2003-2006, Voltage Security, all rights reserved.
 */
#include "vibecrypto.h"
#include "environment.h"
#include "base.h"
#include "libctx.h"
#include "algobj.h"
#include "digest.h"
#include "md5.h"

static void VOLT_CALLING_CONV Decode VOLT_PROTO_LIST ((
   UInt32 *,
   unsigned char *,
   unsigned int
));

int MD5Init (
   VoltAlgorithmObject *obj
   )
{
  VoltDigestClassCtx *digestCtx = (VoltDigestClassCtx *)(obj->classCtx);
  VoltMD5Ctx *md5Ctx = (VoltMD5Ctx *)(digestCtx->localDigestCtx);

  /* Populate the MD5 Ctx with the initial values.
   */
  md5Ctx->countLow = 0;
  md5Ctx->countHigh = 0;
  md5Ctx->currentBlockLen = 0;
  md5Ctx->state[0] = 0x67452301;
  md5Ctx->state[1] = 0xefcdab89;
  md5Ctx->state[2] = 0x98badcfe;
  md5Ctx->state[3] = 0x10325476;

  return (0);
}

int MD5Update (
   VoltAlgorithmObject *obj,
   unsigned char *dataToDigest,
   unsigned int dataToDigestLen
   )
{
  unsigned int copyLen;
  VoltDigestClassCtx *digestCtx = (VoltDigestClassCtx *)(obj->classCtx);
  VoltMD5Ctx *md5Ctx = (VoltMD5Ctx *)(digestCtx->localDigestCtx);
  VoltLibCtx *libCtx = (VoltLibCtx *)(obj->voltObject.libraryCtx);

  if (dataToDigest == (unsigned char *)0)
    dataToDigestLen = 0;

  /* Add the input length to the running total.
   */
  md5Ctx->countLow += dataToDigestLen;
  if (md5Ctx->countLow < dataToDigestLen)
    md5Ctx->countHigh++;

  /* If we have any data in the currentBlock, start there.
   */
  if (md5Ctx->currentBlockLen != 0)
  {
    /* Copy bytes into the currentBlock. If there is enough to complete
     * a block, copy enought to complete the block and then run
     * MD5Transform on it. If not, just copy the input into the block
     * and update currentBlockLen.
     */
    copyLen = dataToDigestLen;
    if ((dataToDigestLen + md5Ctx->currentBlockLen) >= 64)
      copyLen = 64 - md5Ctx->currentBlockLen;
    Z2Memcpy (
      md5Ctx->currentBlock + md5Ctx->currentBlockLen, dataToDigest,
      copyLen);
    md5Ctx->currentBlockLen += copyLen;

    /* If we don't have an entire block, we're done.
     */
    if (md5Ctx->currentBlockLen < 64)
      return (0);

    /* We have a block, process it.
     */
    md5Ctx->MD5Transform ((Pointer)md5Ctx, md5Ctx->currentBlock);
    dataToDigestLen -= copyLen;
    dataToDigest += copyLen;
    md5Ctx->currentBlockLen = 0;
  }

  /* As long as there are complete blocks in the dataToDigest, call
   * MD5Transform on them.
   */
  while (dataToDigestLen >= 64)
  {
    md5Ctx->MD5Transform ((Pointer)md5Ctx, dataToDigest);
    dataToDigestLen -= 64;
    dataToDigest += 64;
  }

  /* If there is any data left over, copy it into the currentBlock. If
   * not, we're done.
   */
  if (dataToDigestLen == 0)
    return (0);

  Z2Memcpy (md5Ctx->currentBlock, dataToDigest, dataToDigestLen);
  md5Ctx->currentBlockLen = dataToDigestLen;

  return (0);
}

int MD5Final (
   VoltAlgorithmObject *obj,
   unsigned char *digest
   )
{
  VoltLibCtx *libCtx = (VoltLibCtx *)(obj->voltObject.libraryCtx);
  VoltDigestClassCtx *digestCtx = (VoltDigestClassCtx *)(obj->classCtx);
  VoltMD5Ctx *md5Ctx = (VoltMD5Ctx *)(digestCtx->localDigestCtx);

  /* Perform padding.
   * currentBlock | 0x80 | 0x00 00 ... 00 | length
   * The length is 8 bytes, the length, in bits, of the input.
   * If there is not enough space left in currentBlock to hold the 0x80
   * byte and the 8 length bytes, finish up the current block with 0x80
   * and 0x00 00 00 ... Then create a new block of all 00's except for
   * the last 8 bytes, the length.
   */
  Z2Memset (
    md5Ctx->currentBlock + md5Ctx->currentBlockLen, 0,
    64 - md5Ctx->currentBlockLen);
  md5Ctx->currentBlock[md5Ctx->currentBlockLen] = 0x80;
  if (md5Ctx->currentBlockLen > 55)
  {
    md5Ctx->MD5Transform ((Pointer)md5Ctx, md5Ctx->currentBlock);
    Z2Memset (md5Ctx->currentBlock, 0, 64);
  }

  /* Set the last 8 bytes to be the length. We added number of bytes,
   * we want bits, so multiply by 8 (a left-shift by 3).
   */
  md5Ctx->countHigh <<= 3;
  md5Ctx->countHigh |= (md5Ctx->countLow >> 29);
  md5Ctx->countLow <<= 3;
  md5Ctx->currentBlock[56] = (unsigned char)(md5Ctx->countLow);
  md5Ctx->currentBlock[57] = (unsigned char)(md5Ctx->countLow >> 8);
  md5Ctx->currentBlock[58] = (unsigned char)(md5Ctx->countLow >> 16);
  md5Ctx->currentBlock[59] = (unsigned char)(md5Ctx->countLow >> 24);
  md5Ctx->currentBlock[60] = (unsigned char)(md5Ctx->countHigh);
  md5Ctx->currentBlock[61] = (unsigned char)(md5Ctx->countHigh >> 8);
  md5Ctx->currentBlock[62] = (unsigned char)(md5Ctx->countHigh >> 16);
  md5Ctx->currentBlock[63] = (unsigned char)(md5Ctx->countHigh >> 24);

  md5Ctx->MD5Transform ((Pointer)md5Ctx, md5Ctx->currentBlock);

  /* The state is the digest.
   */
  digest[0] = (unsigned char)(md5Ctx->state[0]);
  digest[1] = (unsigned char)(md5Ctx->state[0] >> 8);
  digest[2] = (unsigned char)(md5Ctx->state[0] >> 16);
  digest[3] = (unsigned char)(md5Ctx->state[0] >> 24);
  digest[4] = (unsigned char)(md5Ctx->state[1]);
  digest[5] = (unsigned char)(md5Ctx->state[1] >> 8);
  digest[6] = (unsigned char)(md5Ctx->state[1] >> 16);
  digest[7] = (unsigned char)(md5Ctx->state[1] >> 24);
  digest[8] = (unsigned char)(md5Ctx->state[2]);
  digest[9] = (unsigned char)(md5Ctx->state[2] >> 8);
  digest[10] = (unsigned char)(md5Ctx->state[2] >>16);
  digest[11] = (unsigned char)(md5Ctx->state[2] >> 24);
  digest[12] = (unsigned char)(md5Ctx->state[3]);
  digest[13] = (unsigned char)(md5Ctx->state[3] >> 8);
  digest[14] = (unsigned char)(md5Ctx->state[3] >> 16);
  digest[15] = (unsigned char)(md5Ctx->state[3] >> 24);

  return (0);
}

/* Constants for MD5Transform 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

/* 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))))

/* 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) + (UInt32)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
}
#define GG(a, b, c, d, x, s, ac) { \
  (a) += G ((b), (c), (d)) + (x) + (UInt32)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
}
#define HH(a, b, c, d, x, s, ac) { \
  (a) += H ((b), (c), (d)) + (x) + (UInt32)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
}
#define II(a, b, c, d, x, s, ac) { \
  (a) += I ((b), (c), (d)) + (x) + (UInt32)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
}

void MD5Transform (
   Pointer ctx,
   unsigned char *block
   )
{
  VoltMD5Ctx *md5Ctx = (VoltMD5Ctx *)ctx;
  UInt32 a = md5Ctx->state[0];
  UInt32 b = md5Ctx->state[1];
  UInt32 c = md5Ctx->state[2];
  UInt32 d = md5Ctx->state[3];
  UInt32 *x = md5Ctx->xBlock;

  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 */

  md5Ctx->state[0] += a;
  md5Ctx->state[1] += b;
  md5Ctx->state[2] += c;
  md5Ctx->state[3] += d;
}

/* Decodes input (unsigned char) into output (UInt32). Assumes len is
     a multiple of 4.
 */
static void Decode (
   UInt32 *output,
   unsigned char *input,
   unsigned int len
   )
{
  unsigned int 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);
}