text: /* md5.c - an implementation of the MD5 algorithm, based on RFC 1321.
   *
   * Copyright (c) 2007, Aleksey Kravchenko <rhash.admin@gmail.com>
   *
   * Permission to use, copy, modify, and/or distribute this software for any
   * purpose with or without fee is hereby granted.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
   * REGARD TO THIS SOFTWARE  INCLUDING ALL IMPLIED WARRANTIES OF  MERCHANTABILITY
   * AND FITNESS.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
   * INDIRECT,  OR CONSEQUENTIAL DAMAGES  OR ANY DAMAGES WHATSOEVER RESULTING FROM
   * LOSS OF USE,  DATA OR PROFITS,  WHETHER IN AN ACTION OF CONTRACT,  NEGLIGENCE
   * OR OTHER TORTIOUS ACTION,  ARISING OUT OF  OR IN CONNECTION  WITH THE USE  OR
   * PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include <string.h>
  #include "byte_order.h"
  #include "md5.h"
  
  /**
   * Initialize context before calculaing hash.
   *
   * @param ctx context to initialize
   */
  void rhash_md5_init(md5_ctx* ctx)
  {
  	memset(ctx, 0, sizeof(*ctx));
  
  	/* initialize state */
  	ctx->hash[0] = 0x67452301;
  	ctx->hash[1] = 0xefcdab89;
  	ctx->hash[2] = 0x98badcfe;
  	ctx->hash[3] = 0x10325476;
  }
  
  /* First, define four auxiliary functions that each take as input
   * three 32-bit words and returns a 32-bit word.*/
  
  /* F(x,y,z) = ((y XOR z) AND x) XOR z - is faster then original version */
  #define MD5_F(x, y, z) ((((y) ^ (z)) & (x)) ^ (z))
  #define MD5_G(x, y, z) (((x) & (z)) | ((y) & (~z)))
  #define MD5_H(x, y, z) ((x) ^ (y) ^ (z))
  #define MD5_I(x, y, z) ((y) ^ ((x) | (~z)))
  
  /* transformations for rounds 1, 2, 3, and 4. */
  #define MD5_ROUND1(a, b, c, d, x, s, ac) { \
  	(a) += MD5_F((b), (c), (d)) + (x) + (ac); \
  	(a) = ROTL32((a), (s)); \
  	(a) += (b); \
  }
  #define MD5_ROUND2(a, b, c, d, x, s, ac) { \
  	(a) += MD5_G((b), (c), (d)) + (x) + (ac); \
  	(a) = ROTL32((a), (s)); \
  	(a) += (b); \
  }
  #define MD5_ROUND3(a, b, c, d, x, s, ac) { \
  	(a) += MD5_H((b), (c), (d)) + (x) + (ac); \
  	(a) = ROTL32((a), (s)); \
  	(a) += (b); \
  }
  #define MD5_ROUND4(a, b, c, d, x, s, ac) { \
  	(a) += MD5_I((b), (c), (d)) + (x) + (ac); \
  	(a) = ROTL32((a), (s)); \
  	(a) += (b); \
  }
  
  /**
   * The core transformation. Process a 512-bit block.
   * The function has been taken from RFC 1321 with little changes.
   *
   * @param state algorithm state
   * @param x the message block to process
   */
  static void rhash_md5_process_block(unsigned state[4], const unsigned* x)
  {
  	register unsigned a, b, c, d;
  	a = state[0];
  	b = state[1];
  	c = state[2];
  	d = state[3];
  
  	MD5_ROUND1(a, b, c, d, x[ 0],  7, 0xd76aa478);
  	MD5_ROUND1(d, a, b, c, x[ 1], 12, 0xe8c7b756);
  	MD5_ROUND1(c, d, a, b, x[ 2], 17, 0x242070db);
  	MD5_ROUND1(b, c, d, a, x[ 3], 22, 0xc1bdceee);
  	MD5_ROUND1(a, b, c, d, x[ 4],  7, 0xf57c0faf);
  	MD5_ROUND1(d, a, b, c, x[ 5], 12, 0x4787c62a);
  	MD5_ROUND1(c, d, a, b, x[ 6], 17, 0xa8304613);
  	MD5_ROUND1(b, c, d, a, x[ 7], 22, 0xfd469501);
  	MD5_ROUND1(a, b, c, d, x[ 8],  7, 0x698098d8);
  	MD5_ROUND1(d, a, b, c, x[ 9], 12, 0x8b44f7af);
  	MD5_ROUND1(c, d, a, b, x[10], 17, 0xffff5bb1);
  	MD5_ROUND1(b, c, d, a, x[11], 22, 0x895cd7be);
  	MD5_ROUND1(a, b, c, d, x[12],  7, 0x6b901122);
  	MD5_ROUND1(d, a, b, c, x[13], 12, 0xfd987193);
  	MD5_ROUND1(c, d, a, b, x[14], 17, 0xa679438e);
  	MD5_ROUND1(b, c, d, a, x[15], 22, 0x49b40821);
  
  	MD5_ROUND2(a, b, c, d, x[ 1],  5, 0xf61e2562);
  	MD5_ROUND2(d, a, b, c, x[ 6],  9, 0xc040b340);
  	MD5_ROUND2(c, d, a, b, x[11], 14, 0x265e5a51);
  	MD5_ROUND2(b, c, d, a, x[ 0], 20, 0xe9b6c7aa);
  	MD5_ROUND2(a, b, c, d, x[ 5],  5, 0xd62f105d);
  	MD5_ROUND2(d, a, b, c, x[10],  9,  0x2441453);
  	MD5_ROUND2(c, d, a, b, x[15], 14, 0xd8a1e681);
  	MD5_ROUND2(b, c, d, a, x[ 4], 20, 0xe7d3fbc8);
  	MD5_ROUND2(a, b, c, d, x[ 9],  5, 0x21e1cde6);
  	MD5_ROUND2(d, a, b, c, x[14],  9, 0xc33707d6);
  	MD5_ROUND2(c, d, a, b, x[ 3], 14, 0xf4d50d87);
  	MD5_ROUND2(b, c, d, a, x[ 8], 20, 0x455a14ed);
  	MD5_ROUND2(a, b, c, d, x[13],  5, 0xa9e3e905);
  	MD5_ROUND2(d, a, b, c, x[ 2],  9, 0xfcefa3f8);
  	MD5_ROUND2(c, d, a, b, x[ 7], 14, 0x676f02d9);
  	MD5_ROUND2(b, c, d, a, x[12], 20, 0x8d2a4c8a);
  
  	MD5_ROUND3(a, b, c, d, x[ 5],  4, 0xfffa3942);
  	MD5_ROUND3(d, a, b, c, x[ 8], 11, 0x8771f681);
  	MD5_ROUND3(c, d, a, b, x[11], 16, 0x6d9d6122);
  	MD5_ROUND3(b, c, d, a, x[14], 23, 0xfde5380c);
  	MD5_ROUND3(a, b, c, d, x[ 1],  4, 0xa4beea44);
  	MD5_ROUND3(d, a, b, c, x[ 4], 11, 0x4bdecfa9);
  	MD5_ROUND3(c, d, a, b, x[ 7], 16, 0xf6bb4b60);
  	MD5_ROUND3(b, c, d, a, x[10], 23, 0xbebfbc70);
  	MD5_ROUND3(a, b, c, d, x[13],  4, 0x289b7ec6);
  	MD5_ROUND3(d, a, b, c, x[ 0], 11, 0xeaa127fa);
  	MD5_ROUND3(c, d, a, b, x[ 3], 16, 0xd4ef3085);
  	MD5_ROUND3(b, c, d, a, x[ 6], 23,  0x4881d05);
  	MD5_ROUND3(a, b, c, d, x[ 9],  4, 0xd9d4d039);
  	MD5_ROUND3(d, a, b, c, x[12], 11, 0xe6db99e5);
  	MD5_ROUND3(c, d, a, b, x[15], 16, 0x1fa27cf8);
  	MD5_ROUND3(b, c, d, a, x[ 2], 23, 0xc4ac5665);
  
  	MD5_ROUND4(a, b, c, d, x[ 0],  6, 0xf4292244);
  	MD5_ROUND4(d, a, b, c, x[ 7], 10, 0x432aff97);
  	MD5_ROUND4(c, d, a, b, x[14], 15, 0xab9423a7);
  	MD5_ROUND4(b, c, d, a, x[ 5], 21, 0xfc93a039);
  	MD5_ROUND4(a, b, c, d, x[12],  6, 0x655b59c3);
  	MD5_ROUND4(d, a, b, c, x[ 3], 10, 0x8f0ccc92);
  	MD5_ROUND4(c, d, a, b, x[10], 15, 0xffeff47d);
  	MD5_ROUND4(b, c, d, a, x[ 1], 21, 0x85845dd1);
  	MD5_ROUND4(a, b, c, d, x[ 8],  6, 0x6fa87e4f);
  	MD5_ROUND4(d, a, b, c, x[15], 10, 0xfe2ce6e0);
  	MD5_ROUND4(c, d, a, b, x[ 6], 15, 0xa3014314);
  	MD5_ROUND4(b, c, d, a, x[13], 21, 0x4e0811a1);
  	MD5_ROUND4(a, b, c, d, x[ 4],  6, 0xf7537e82);
  	MD5_ROUND4(d, a, b, c, x[11], 10, 0xbd3af235);
  	MD5_ROUND4(c, d, a, b, x[ 2], 15, 0x2ad7d2bb);
  	MD5_ROUND4(b, c, d, a, x[ 9], 21, 0xeb86d391);
  
  	state[0] += a;
  	state[1] += b;
  	state[2] += c;
  	state[3] += d;
  }
  
  /**
   * Calculate message hash.
   * Can be called repeatedly with chunks of the message to be hashed.
   *
   * @param ctx the algorithm context containing current hashing state
   * @param msg message chunk
   * @param size length of the message chunk
   */
  void rhash_md5_update(md5_ctx* ctx, const unsigned char* msg, size_t size)
  {
  	unsigned index = (unsigned)ctx->length & 63;
  	ctx->length += size;
  
  	/* fill partial block */
  	if (index) {
  		unsigned left = md5_block_size - index;
  		le32_copy(ctx->message, index, msg, (size < left ? size : left));
  		if (size < left) return;
  
  		/* process partial block */
  		rhash_md5_process_block(ctx->hash, ctx->message);
  		msg  += left;
  		size -= left;
  	}
  	while (size >= md5_block_size) {
  		unsigned* aligned_message_block;
  		if (IS_LITTLE_ENDIAN && IS_ALIGNED_32(msg)) {
  			/* the most common case is processing a 32-bit aligned message
  			on a little-endian CPU without copying it */
  			aligned_message_block = (unsigned*)msg;
  		} else {
  			le32_copy(ctx->message, 0, msg, md5_block_size);
  			aligned_message_block = ctx->message;
  		}
  
  		rhash_md5_process_block(ctx->hash, aligned_message_block);
  		msg  += md5_block_size;
  		size -= md5_block_size;
  	}
  	if (size) {
  		/* save leftovers */
  		le32_copy(ctx->message, 0, msg, size);
  	}
  }
  
  /**
   * Store calculated hash into the given array.
   *
   * @param ctx the algorithm context containing current hashing state
   * @param result calculated hash in binary form
   */
  void rhash_md5_final(md5_ctx* ctx, unsigned char* result)
  {
  	unsigned index = ((unsigned)ctx->length & 63) >> 2;
  	unsigned shift = ((unsigned)ctx->length & 3) * 8;
  
  	/* pad message and run for last block */
  
  	/* append the byte 0x80 to the message */
  	ctx->message[index]   &= ~(0xFFFFFFFFu << shift);
  	ctx->message[index++] ^= 0x80u << shift;
  
  	/* if no room left in the message to store 64-bit message length */
  	if (index > 14) {
  		/* then fill the rest with zeros and process it */
  		while (index < 16) {
  			ctx->message[index++] = 0;
  		}
  		rhash_md5_process_block(ctx->hash, ctx->message);
  		index = 0;
  	}
  	while (index < 14) {
  		ctx->message[index++] = 0;
  	}
  	ctx->message[14] = (unsigned)(ctx->length << 3);
  	ctx->message[15] = (unsigned)(ctx->length >> 29);
  	rhash_md5_process_block(ctx->hash, ctx->message);
  
  	if (result) le32_copy(result, 0, &ctx->hash, 16);
  }
  