Let E be a strong pseudorandom permutation (or SPRP) secure enciphering scheme (i.e., a length-preserving encryption scheme) which can only encrypt messages of size multiple of n, the block size of the underlying block cipher. There are several such constructions, e.g., CBC mode or cipher block chaining mode. In this paper we present how a secure enciphering scheme E can be obtained which can e...

Online ciphers encrypt an arbitrary number of plaintext blocks and output ciphertext blocks which only depend on the preceding plaintext blocks. All online ciphers proposed so far are essentially serial, which significantly limits their performance on parallel architectures such as modern general-purpose CPUs or dedicated hardware. We propose the first parallelizable online cipher, COPE. It per...

The security of block ciphers is assessed through their resistance to known attacks. One of the most important attacks is linear cryptanalysis. In this paper, we describe a model for presenting linear approximations for Moamagar block cipher. This graph shows the whole space of linear approximations for the block cipher algorithm is presented through its obtained multi-level weighted directed g...

The 128-bit block cipher TWIS was proposed by Ojha et al in 2009. It is a lightweight block cipher and its design is inspired from CLEFIA. In this paper, we first study the properties of TWIS structure, and as an extension we also considered the generalized TWIS-type structure which can be called G-TWIS cipher, where the block size and round number can be arbitrary values. Then we present a ser...

We describe a block-cipher mode of operation, CMC, that turns an n-bit block cipher intoa tweakable enciphering scheme that acts on strings of mn bits, where m ≥ 2. When theunderlying block cipher is secure in the sense of a strong pseudorandom permutation (PRP),our scheme is secure in the sense of tweakable, strong PRP. Such an object can be used toencipher the sectors of a dis...

Modes of operation adapt block ciphers to many applications. Among the encryption modes, only CFB (Cipher Feedback) has both of the following properties: Firstly it allows transmission units shorter than the block-cipher length to be encrypted and sent without delay and message expansion. Secondly, it can resynchronize after the loss of such transmission units. However, CFB is ine cient in such...

Block cipher encryption algorithms generally process on word structures of fixed length such as 8 or 16bits. IDEA is one of the most widely used block ciphers and operates on 16-bit words. Square analysis is a method that exploits the word structure of block ciphers. Some square distinguishers of IDEA are given in previous studies. The best attacks against IDEA use square-like techniques. In th...

The application of block ciphers in the modern society is enormous. One branch of this development is getting a new dimension – the application of quasigroups and quasigroup transformations in the block ciphers. This paper contains the results of the research involving the family of block ciphers named SQBC (Small Quasigroup Block Cipher), which is based on quasigroups and quasigroup transforma...

In the era of information technology, security is essential to transmit confidential information (like credit card details, banking transactions etc) over the unsecured network like internet. It is possibility that the information that is being transferred through network of computers or internet being read by other people. For this we need an efficient and secure way to protect our data. Crypt...