COUNTERMODE DEVELOPMENT FOR BLOCK CIPHER OPERATIONS

There are two basic types of symmetric cipher: block ciphers and stream ciphers. blockciphers operate on blocks of plaintext and ciphertext—usually of 64 bits but sometimes longer. stream ciphers operate on streams of plaintext and ciphertext one bit or byte (sometimes even one 32-bit word) at a time. the block cipher modes of operation can be applied as both stream and block cipher.in this paper we introduce three developments of counter mode of operation of block cipher. these developments merge between advantages of counter mode with other modes. this gives a good secure modes for general purpose block-oriented transmission authentication, random access, streamoriented transmission over noisy channel