text: /* md5.c */
  /*
      This file is part of the AVR-Crypto-Lib.
      Copyright (C) 2008  Daniel Otte (daniel.otte@rub.de)
  
      This program is free software: you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published by
      the Free Software Foundation, either version 3 of the License, or
      (at your option) any later version.
  
      This program is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      GNU General Public License for more details.
  
      You should have received a copy of the GNU General Public License
      along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
  /* 
   * \file	md5.c
   * \author	Daniel Otte
   * \date 	2006-07-31
   * \license GPLv3 or later
   * \brief   Implementation of the MD5 hash algorithm as described in RFC 1321
   * 
   */
  
   #include "md5.h"
   #include "md5_sbox.h"
   #include <stdint.h>
   #include <string.h>
   
   #undef DEBUG
   
  void md5_init(md5_ctx_t *s){
  	s->counter = 0;
  	s->a[0] = 0x67452301;
  	s->a[1] = 0xefcdab89;
  	s->a[2] = 0x98badcfe;
  	s->a[3] = 0x10325476;
  }
  
  static 
  uint32_t md5_F(uint32_t x, uint32_t y, uint32_t z){
  	return ((x&y)|((~x)&z));
  }
  
  static
  uint32_t md5_G(uint32_t x, uint32_t y, uint32_t z){
  	return ((x&z)|((~z)&y));
  }
  
  static
  uint32_t md5_H(uint32_t x, uint32_t y, uint32_t z){
  	return (x^y^z);
  }
  
  static
  uint32_t md5_I(uint32_t x, uint32_t y, uint32_t z){
  	return (y ^ (x | (~z)));
  }
  
  typedef uint32_t md5_func_t(uint32_t, uint32_t, uint32_t);
  
  #define ROTL32(x,n) (((x)<<(n)) | ((x)>>(32-(n))))  
  
  static
  void md5_core(uint32_t* a, void* block, uint8_t as, uint8_t s, uint8_t i, uint8_t fi){
  	uint32_t t;
  	md5_func_t* funcs[]={md5_F, md5_G, md5_H, md5_I};
  	as &= 0x3;
  	/* a = b + ((a + F(b,c,d) + X[k] + T[i]) <<< s). */
  #ifdef DEBUG
  	char funcc[]={'*', '-', '+', '~'};
  	cli_putstr("\r\n DBG: md5_core [");
  	cli_putc(funcc[fi]);
  	cli_hexdump(&as, 1); cli_putc(' ');
  	cli_hexdump(&k, 1); cli_putc(' ');
  	cli_hexdump(&s, 1); cli_putc(' ');
  	cli_hexdump(&i, 1); cli_putc(']');
  #endif	
  	t = a[as] + funcs[fi](a[(as+1)&3], a[(as+2)&3], a[(as+3)&3]) 
  	    + *((uint32_t*)block) + pgm_read_dword(md5_T+i) ;
  	a[as]=a[(as+1)&3] + ROTL32(t, s);
  }
  
  void md5_nextBlock(md5_ctx_t *state, const void* block){
  	uint32_t	a[4];
  	uint8_t		m,n,i=0;
  	/* this requires other mixed sboxes */
  #ifdef DEBUG
  	cli_putstr("\r\n DBG: md5_nextBlock: block:\r\n");
  	cli_hexdump(block, 16);	cli_putstr("\r\n");
  	cli_hexdump(block+16, 16);	cli_putstr("\r\n");
  	cli_hexdump(block+32, 16);	cli_putstr("\r\n");
  	cli_hexdump(block+48, 16);	cli_putstr("\r\n");
  #endif	
  	
  	a[0]=state->a[0];
  	a[1]=state->a[1];
  	a[2]=state->a[2];
  	a[3]=state->a[3];
  	
  	/* round 1 */
  	uint8_t s1t[]={7,12,17,22}; // 1,-1   1,4   2,-1   3,-2
  	for(m=0;m<4;++m){
  		for(n=0;n<4;++n){
  			md5_core(a, &(((uint32_t*)block)[m*4+n]), 4-n, s1t[n],i++,0);
  		}
  	}
  	/* round 2 */
  	uint8_t s2t[]={5,9,14,20}; // 1,-3   1,1   2,-2   2,4
  	for(m=0;m<4;++m){
  		for(n=0;n<4;++n){
  			md5_core(a, &(((uint32_t*)block)[(1+m*4+n*5)&0xf]), 4-n, s2t[n],i++,1);
  		}
  	}
  	/* round 3 */
  	uint8_t s3t[]={4,11,16,23}; // 0,4   1,3   2,0   3,-1
  	for(m=0;m<4;++m){
  		for(n=0;n<4;++n){
  			md5_core(a, &(((uint32_t*)block)[(5-m*4+n*3)&0xf]), 4-n, s3t[n],i++,2);
  		}
  	}
  	/* round 4 */
  	uint8_t s4t[]={6,10,15,21}; // 1,-2   1,2   2,-1   3,-3
  	for(m=0;m<4;++m){
  		for(n=0;n<4;++n){
  			md5_core(a, &(((uint32_t*)block)[(0-m*4+n*7)&0xf]), 4-n, s4t[n],i++,3);
  		}
  	}
  	state->a[0] += a[0];
  	state->a[1] += a[1];
  	state->a[2] += a[2];
  	state->a[3] += a[3];
  	state->counter++;
  }
  
  void md5_lastBlock(md5_ctx_t *state, const void* block, uint16_t length_b){
  	uint16_t l;
  	union {
  		uint8_t   v8[64];
  		uint64_t v64[ 8];
  	} buffer;
  	while (length_b >= 512){
  		md5_nextBlock(state, block);
  		length_b -= 512;
  		block = ((uint8_t*)block) + 512/8;
  	}
  	memset(buffer.v8, 0, 64);
  	memcpy(buffer.v8, block, length_b/8);
  	/* insert padding one */
  	l=length_b/8;
  	if(length_b%8){
  		uint8_t t;
  		t = ((uint8_t*)block)[l];
  		t |= (0x80>>(length_b%8));
  		buffer.v8[l]=t;
  	}else{
  		buffer.v8[l]=0x80;
  	}
  	/* insert length value */
  	if(l+sizeof(uint64_t) >= 512/8){
  		md5_nextBlock(state, buffer.v8);
  		state->counter--;
  		memset(buffer.v8, 0, 64-8);
  	}
  	buffer.v64[7] = (state->counter * 512) + length_b;
  	md5_nextBlock(state, buffer.v8);
  }
  
  void md5_ctx2hash(md5_hash_t* dest, const md5_ctx_t* state){
  	memcpy(dest, state->a, MD5_HASH_BYTES);
  }
  
  void md5_1(md5_hash_t* dest, const void* msg, uint32_t length_b){
  	md5_ctx_t ctx;
  	md5_init(&ctx);
  	while(length_b>=MD5_BLOCK_BITS){
  		md5_nextBlock(&ctx, msg);
  		msg = (uint8_t*)msg + MD5_BLOCK_BYTES;
  		length_b -= MD5_BLOCK_BITS;
  	}
  	md5_lastBlock(&ctx, msg, length_b);
  	md5_ctx2hash(dest, &ctx);
  }
  
  