source/blockhash.h

   1 #ifndef MSP_CRYPTO_BLOCKHASH_H_
   2 #define MSP_CRYPTO_BLOCKHASH_H_
   3
   4 #include <algorithm>
   5 #include "hash.h"
   6
   7 namespace Msp {
   8 namespace Crypto {
   9
  10 template<unsigned B>
  11 class BlockHash: public Hash
  12 {
  13 protected:
  14         enum
  15         {
  16                 BLOCK_SIZE = B
  17         };
  18
  19         char unprocessed[BLOCK_SIZE];
  20         unsigned unprocessed_bytes;
  21
  22         BlockHash();
  23
  24 public:
  25         using Hash::update;
  26         virtual void update(const char *, unsigned);
  27
  28 protected:
  29         virtual void process_block(const char *) = 0;
  30 };
  31
  32
  33 template<unsigned B>
  34 inline BlockHash<B>::BlockHash():
  35         unprocessed_bytes(0)
  36 { }
  37
  38 template<unsigned B>
  39 void BlockHash<B>::update(const char *data, unsigned len)
  40 {
  41         if(unprocessed_bytes && unprocessed_bytes+len>=BLOCK_SIZE)
  42         {
  43                 unsigned needed = BLOCK_SIZE-unprocessed_bytes;
  44                 std::copy(data, data+needed, unprocessed+unprocessed_bytes);
  45                 process_block(unprocessed);
  46                 data += needed;
  47                 len -= needed;
  48                 unprocessed_bytes = 0;
  49         }
  50
  51         while(len>=BLOCK_SIZE)
  52         {
  53                 process_block(data);
  54                 data += BLOCK_SIZE;
  55                 len -= BLOCK_SIZE;
  56         }
  57
  58         if(len>0)
  59         {
  60                 std::copy(data, data+len, unprocessed+unprocessed_bytes);
  61                 unprocessed_bytes += len;
  62         }
  63 }
  64
  65 } // namespace Crypto
  66 } // namespace Msp
  67
  68 #endif