Distributed Decryption of Word-Oriented Stream Ciphers

The distributed decryption scheme for simple addition stream ciphers proposed by Magnus berg is analyzed. Its main disadvantages, i.e. the operations of encryption and decryption are implemented in different finite fields, and the orders of the two fields must be primes satisfying a certain relation, are pointed out. A new distributed decryption scheme for word-oriented stream ciphers is presented. Compared with Magnus bergs scheme, the proposed scheme has two main advantages. Firstly, in the new scheme, the encryption and decryption operations are implemented in the same finite field, and the size of the field is not required to be a prime. Secondly, the security and efficiency of the new scheme are greatly improved. For applications, the new scheme can be applied in the protection of data confidentiality in a database, distributed key management in Ad-hoc networks, etc.