text: /*
   *  Copyright (C) 2017 - This file is part of libecc project
   *
   *  Authors:
   *      Ryad BENADJILA <ryadbenadjila@gmail.com>
   *      Arnaud EBALARD <arnaud.ebalard@ssi.gouv.fr>
   *      Jean-Pierre FLORI <jean-pierre.flori@ssi.gouv.fr>
   *
   *  Contributors:
   *      Nicolas VIVET <nicolas.vivet@ssi.gouv.fr>
   *      Karim KHALFALLAH <karim.khalfallah@ssi.gouv.fr>
   *
   *  This software is licensed under a dual BSD and GPL v2 license.
   *  See LICENSE file at the root folder of the project.
   */
  #include "../utils/utils.h"
  #include "sha3.h"
  
  /* Init function depending on the digest size */
  void _sha3_init(sha3_context *ctx, u8 digest_size)
  {
  	/* Check given inpur digest size: we only consider KECCAK versions 
  	 * mapped on SHA-3 instances (224, 256, 384, 512).
  	 */
          MUST_HAVE( (digest_size == (224/8)) || (digest_size == (256/8)) || \
                  (digest_size == (384/8)) || (digest_size == (512/8)) );
  
  	MUST_HAVE(ctx != NULL);
  
          /* Zeroize the internal state */
          local_memset(ctx->sha3_state, 0, sizeof(ctx->sha3_state));
  
          ctx->sha3_idx = 0;
          ctx->sha3_digest_size = digest_size;
          ctx->sha3_block_size = (KECCAK_SLICES * KECCAK_SLICES * sizeof(u64)) - (2 * digest_size);
  
  	/* Detect endianness */
  	ctx->sha3_endian = arch_is_big_endian() ? SHA3_BIG : SHA3_LITTLE;
  
          return;
  }
  
  /* Update hash function */
  void _sha3_update(sha3_context *ctx, const u8 *input, u32 ilen)
  {
          u32 i;
          u8 *state;
  
  	MUST_HAVE((ctx != NULL) && (input != NULL));
  
          state = (u8*)(ctx->sha3_state);
  
          for(i = 0; i < ilen; i++){
                  /* Compute the index depending on the endianness */
                  u64 idx = (ctx->sha3_endian == SHA3_LITTLE) ? ctx->sha3_idx : SWAP64_Idx(ctx->sha3_idx);
                  ctx->sha3_idx++;
                  /* Update the state, and adapt endianness order */
                  state[idx] ^= input[i];
                  if(ctx->sha3_idx == ctx->sha3_block_size){
                          KECCAKF(ctx->sha3_state);
                          ctx->sha3_idx = 0;
                  }
          }
  
          return;
  }
  
  /* Finalize hash function */
  void _sha3_finalize(sha3_context *ctx, u8 *output)
  {
          unsigned int i;
          u8 *state;
  
  	MUST_HAVE((ctx != NULL) && (output != NULL));
  	MUST_HAVE(ctx->sha3_digest_size <= sizeof(ctx->sha3_state));
  
          state = (u8*)(ctx->sha3_state);
  
          /* Proceed with the padding of the last block */
          /* Compute the index depending on the endianness */
          if(ctx->sha3_endian == SHA3_LITTLE){
                  /* Little endian case */
                  state[ctx->sha3_idx] ^= 0x06;
                  state[ctx->sha3_block_size - 1] ^= 0x80;
          }
          else{
                  /* Big endian case */
                  state[SWAP64_Idx(ctx->sha3_idx)] ^= 0x06;
                  state[SWAP64_Idx(ctx->sha3_block_size - 1)] ^= 0x80;
          }
          KECCAKF(ctx->sha3_state);
          for(i = 0; i < ctx->sha3_digest_size; i++){
                  output[i] = (ctx->sha3_endian == SHA3_LITTLE) ? state[i] : state[SWAP64_Idx(i)];
          }
  
          return;
  }
  