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    /*
     * $Id$
     *
     *  md5.c :  Implementation of the MD5 hash function
     *
     * Part of the Python Cryptography Toolkit, version 1.0.1
     * Colin Plumb's original code modified by A.M. Kuchling
     *
     * Further hacked and adapted to pike by Niels Mller
     */
    
    #include "crypto_types.h"
    #include "md5.h"
    
    
    #include <string.h>
    
    
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    void md5_copy(struct md5_ctx *dest, struct md5_ctx *src)
    {
      int i;
      dest->count_l=src->count_l;
      dest->count_h=src->count_h;
      for(i=0; i<MD5_DIGESTLEN; i++)
        dest->digest[i]=src->digest[i];
      for(i=0; i < src->index; i++)
        dest->block[i] = src->block[i];
      dest->index = src->index;
    }
    
    void md5_init(struct md5_ctx *ctx)
    {
      ctx->digest[0] = 0x67452301;
      ctx->digest[1] = 0xefcdab89;
      ctx->digest[2] = 0x98badcfe;
      ctx->digest[3] = 0x10325476;
      
      ctx->count_l = ctx->count_h = 0;
      ctx->index = 0;
    }
    
    /* MD5 functions */
    #define F1(x, y, z) (z ^ (x & (y ^ z)))
    #define F2(x, y, z) F1(z, x, y)
    #define F3(x, y, z) (x ^ y ^ z)
    #define F4(x, y, z) (y ^ (x | ~z))
    
    #define ROUND(f, w, x, y, z, data, s) \
    ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )
      
    /* Perform the MD5 transformation on one full block of 16 32-bit words. */
       
    
    static void md5_transform(struct md5_ctx *ctx, UINT32 *data)
    
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    {
    
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      a = ctx->digest[0];
      b = ctx->digest[1];
      c = ctx->digest[2];
      d = ctx->digest[3];
    
      ROUND(F1, a, b, c, d, data[ 0] + 0xd76aa478, 7);
      ROUND(F1, d, a, b, c, data[ 1] + 0xe8c7b756, 12);
      ROUND(F1, c, d, a, b, data[ 2] + 0x242070db, 17);
      ROUND(F1, b, c, d, a, data[ 3] + 0xc1bdceee, 22);
      ROUND(F1, a, b, c, d, data[ 4] + 0xf57c0faf, 7);
      ROUND(F1, d, a, b, c, data[ 5] + 0x4787c62a, 12);
      ROUND(F1, c, d, a, b, data[ 6] + 0xa8304613, 17);
      ROUND(F1, b, c, d, a, data[ 7] + 0xfd469501, 22);
      ROUND(F1, a, b, c, d, data[ 8] + 0x698098d8, 7);
      ROUND(F1, d, a, b, c, data[ 9] + 0x8b44f7af, 12);
      ROUND(F1, c, d, a, b, data[10] + 0xffff5bb1, 17);
      ROUND(F1, b, c, d, a, data[11] + 0x895cd7be, 22);
      ROUND(F1, a, b, c, d, data[12] + 0x6b901122, 7);
      ROUND(F1, d, a, b, c, data[13] + 0xfd987193, 12);
      ROUND(F1, c, d, a, b, data[14] + 0xa679438e, 17);
      ROUND(F1, b, c, d, a, data[15] + 0x49b40821, 22);
    
      ROUND(F2, a, b, c, d, data[ 1] + 0xf61e2562, 5);
      ROUND(F2, d, a, b, c, data[ 6] + 0xc040b340, 9);
      ROUND(F2, c, d, a, b, data[11] + 0x265e5a51, 14);
      ROUND(F2, b, c, d, a, data[ 0] + 0xe9b6c7aa, 20);
      ROUND(F2, a, b, c, d, data[ 5] + 0xd62f105d, 5);
      ROUND(F2, d, a, b, c, data[10] + 0x02441453, 9);
      ROUND(F2, c, d, a, b, data[15] + 0xd8a1e681, 14);
      ROUND(F2, b, c, d, a, data[ 4] + 0xe7d3fbc8, 20);
      ROUND(F2, a, b, c, d, data[ 9] + 0x21e1cde6, 5);
      ROUND(F2, d, a, b, c, data[14] + 0xc33707d6, 9);
      ROUND(F2, c, d, a, b, data[ 3] + 0xf4d50d87, 14);
      ROUND(F2, b, c, d, a, data[ 8] + 0x455a14ed, 20);
      ROUND(F2, a, b, c, d, data[13] + 0xa9e3e905, 5);
      ROUND(F2, d, a, b, c, data[ 2] + 0xfcefa3f8, 9);
      ROUND(F2, c, d, a, b, data[ 7] + 0x676f02d9, 14);
      ROUND(F2, b, c, d, a, data[12] + 0x8d2a4c8a, 20);
    
      ROUND(F3, a, b, c, d, data[ 5] + 0xfffa3942, 4);
      ROUND(F3, d, a, b, c, data[ 8] + 0x8771f681, 11);
      ROUND(F3, c, d, a, b, data[11] + 0x6d9d6122, 16);
      ROUND(F3, b, c, d, a, data[14] + 0xfde5380c, 23);
      ROUND(F3, a, b, c, d, data[ 1] + 0xa4beea44, 4);
      ROUND(F3, d, a, b, c, data[ 4] + 0x4bdecfa9, 11);
      ROUND(F3, c, d, a, b, data[ 7] + 0xf6bb4b60, 16);
      ROUND(F3, b, c, d, a, data[10] + 0xbebfbc70, 23);
      ROUND(F3, a, b, c, d, data[13] + 0x289b7ec6, 4);
      ROUND(F3, d, a, b, c, data[ 0] + 0xeaa127fa, 11);
      ROUND(F3, c, d, a, b, data[ 3] + 0xd4ef3085, 16);
      ROUND(F3, b, c, d, a, data[ 6] + 0x04881d05, 23);
      ROUND(F3, a, b, c, d, data[ 9] + 0xd9d4d039, 4);
      ROUND(F3, d, a, b, c, data[12] + 0xe6db99e5, 11);
      ROUND(F3, c, d, a, b, data[15] + 0x1fa27cf8, 16);
      ROUND(F3, b, c, d, a, data[ 2] + 0xc4ac5665, 23);
    
      ROUND(F4, a, b, c, d, data[ 0] + 0xf4292244, 6);
      ROUND(F4, d, a, b, c, data[ 7] + 0x432aff97, 10);
      ROUND(F4, c, d, a, b, data[14] + 0xab9423a7, 15);
      ROUND(F4, b, c, d, a, data[ 5] + 0xfc93a039, 21);
      ROUND(F4, a, b, c, d, data[12] + 0x655b59c3, 6);
      ROUND(F4, d, a, b, c, data[ 3] + 0x8f0ccc92, 10);
      ROUND(F4, c, d, a, b, data[10] + 0xffeff47d, 15);
      ROUND(F4, b, c, d, a, data[ 1] + 0x85845dd1, 21);
      ROUND(F4, a, b, c, d, data[ 8] + 0x6fa87e4f, 6);
      ROUND(F4, d, a, b, c, data[15] + 0xfe2ce6e0, 10);
      ROUND(F4, c, d, a, b, data[ 6] + 0xa3014314, 15);
      ROUND(F4, b, c, d, a, data[13] + 0x4e0811a1, 21);
      ROUND(F4, a, b, c, d, data[ 4] + 0xf7537e82, 6);
      ROUND(F4, d, a, b, c, data[11] + 0xbd3af235, 10);
      ROUND(F4, c, d, a, b, data[ 2] + 0x2ad7d2bb, 15);
      ROUND(F4, b, c, d, a, data[ 9] + 0xeb86d391, 21);
    
      ctx->digest[0] += a;
      ctx->digest[1] += b;
      ctx->digest[2] += c;
      ctx->digest[3] += d;
    }
    
    #ifndef EXTRACT_UCHAR
    #define EXTRACT_UCHAR(p)  (*(unsigned char *)(p))
    #endif
    
    /* Note that MD5 uses little endian byteorder */
    
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    #define STRING2INT(s) ((((((EXTRACT_UCHAR(s+3) << 8)	\
    			  | EXTRACT_UCHAR(s+2)) << 8)	\
    			  | EXTRACT_UCHAR(s+1)) << 8)	\
    		          | EXTRACT_UCHAR(s))
    
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    static void
    md5_block(struct md5_ctx *ctx, const UINT8 *block)
    
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    {
    
      UINT32 data[MD5_DATALEN];
    
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      int i;
      
      /* Update block count */
      if (!++ctx->count_l)
        ++ctx->count_h;
    
      /* Endian independent conversion */
      for (i = 0; i<16; i++, block += 4)
        data[i] = STRING2INT(block);
    
      md5_transform(ctx, data);
    }
    
    
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    void
    md5_update(struct md5_ctx *ctx,
    	   const UINT8 *buffer,
    	   UINT32 len)
    
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    {
      if (ctx->index)
      { /* Try to fill partial block */
        unsigned left = MD5_DATASIZE - ctx->index;
        if (len < left)
        {
          memcpy(ctx->block + ctx->index, buffer, len);
          ctx->index += len;
          return; /* Finished */
        }
        else
        {
          memcpy(ctx->block + ctx->index, buffer, left);
          md5_block(ctx, ctx->block);
          buffer += left;
          len -= left;
        }
      }
      while (len >= MD5_DATASIZE)
      {
        md5_block(ctx, buffer);
        buffer += MD5_DATASIZE;
        len -= MD5_DATASIZE;
      }
      if ((ctx->index = len))     /* This assignment is intended */
        /* Buffer leftovers */
        memcpy(ctx->block, buffer, len);
    }
    
    /* Final wrapup - pad to MD5_DATASIZE-byte boundary with the bit pattern
       1 0* (64-bit count of bits processed, LSB-first) */
    
    void md5_final(struct md5_ctx *ctx)
    {
    
      UINT32 data[MD5_DATALEN];
    
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      int i;
      int words;
      
      i = ctx->index;
      /* Set the first char of padding to 0x80.  This is safe since there is
         always at least one byte free */
      ctx->block[i++] = 0x80;
    
      /* Fill rest of word */
      for( ; i & 3; i++)
        ctx->block[i] = 0;
    
      /* i is now a multiple of the word size 4 */
      words = i >> 2;
      for (i = 0; i < words; i++)
        data[i] = STRING2INT(ctx->block + 4*i);
      
      if (words > (MD5_DATALEN-2))
        { /* No room for length in this block. Process it and
           * pad with another one */
          for (i = words ; i < MD5_DATALEN; i++)
    	data[i] = 0;
          md5_transform(ctx, data);
          for (i = 0; i < (MD5_DATALEN-2); i++)
    	data[i] = 0;
        }
      else
        for (i = words ; i < MD5_DATALEN - 2; i++)
          data[i] = 0;
      /* Theres 512 = 2^9 bits in one block 
       * Little-endian order => Least significant word first */
      data[MD5_DATALEN-1] = (ctx->count_h << 9) | (ctx->count_l >> 23);
      data[MD5_DATALEN-2] = (ctx->count_l << 9) | (ctx->index << 3);
      md5_transform(ctx, data);
    }
    
    
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    void
    md5_digest(struct md5_ctx *ctx, UINT8 *s)
    
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    {
      int i;
    
      /* Little endian order */
      for (i = 0; i < MD5_DIGESTLEN; i++)
        {
          *s++ = 0xff &  ctx->digest[i];
          *s++ = 0xff & (ctx->digest[i] >> 8);
          *s++ = 0xff & (ctx->digest[i] >> 16);
          *s++ =         ctx->digest[i] >> 24;
        }
    }