Motivated by applications such as databases with nonuniform field lengths, we introduce the concept of an elastic block cipher, a new approach to variable length block ciphers which incorporates fixed sized cipher components into a new network structure. Our scheme allows us to dynamically “stretch” the supported block size of a block cipher up to a length double the original block size, while ...

This paper proposes a new block cipher called KT-64. We make a cipher using components that are believed secure. The structure of KT-64 is very simple, strong and efficient. We use the controlled substitution-permutation networks (CSPNs) based on controlled elements (CEs) for designing fast block cipher suitable to cheap hardware implementation. Security estimations of KT64 cipher show that pro...

In this paper, we use a high-order iterated function generated by block cipher as the nonlinear filter to improve the security of stream cipher. Moreover, by combining the published rounds function in block cipher and OFB as the nonlinear functional mode with an extra memory module, we enable to control the nonlinear complexity of the design. This new approach fuses the block cipher operation m...

Impossible Differential Cryptanalysis(IDC) [4] uses impossible differential characteristics to retrieve a subkey material for the first or the last several rounds of block ciphers. Thus, the security of a block cipher against IDC can be evaluated by impossible differential characteristics. In this paper, we study impossible differential characteristics of block cipher structures whose round fun...

The CBC-MAC or cipher block chaining message authentication code, is a well-known method to generate message authentication codes. Unfortunately, it is not forgery-secure over an arbitrary domain. There are several secure variants of CBC-MAC, among which OMAC is a widely-used candidate. To authenticate an s-block message, OMAC costs (s+1) block cipher encryptions (one of these is a zero block e...

We present a new, misuse-resistant scheme for online authenticated encryption, following the framework set forth by Fleischmann et al. (FSE 2012). Our scheme, COBRA, is roughly as efficient as the GCM mode of operation for nonce-based authenticated encryption, performing one block cipher call plus one finite field multiplication per message block in a parallelizable way. The major difference fr...

We propose a key feedback mode of operation for the AES algorithm Rijndael (or any other block cipher), giving efficient synchronous keystream generators. We show that if the block cipher possesses simple properties, normally accepted to exist in any secure block cipher, then also the generator is secure.

The Common Scrambling Algorithm (CSA) is used to encrypt streams of video data in the Digital Video Broadcasting (DVB) system. The algorithm cascades a stream and a block cipher, apparently for a larger security margin. In this paper we set out to analyze the block cipher and the stream cipher separately and give an overview of how they interact with each other. We present a practical attack on...

We introduce the new concept of elastic block ciphers, symmetrickey encryption algorithms that (1) for a variable-size input do not expand the plaintext (i.e., do not require plaintext padding) and (2) adjust their computational load proportionally to the size increase. Contrary to stream ciphers, elastic block ciphers maintain the diffusion property and non-synchronicity of traditional block c...

Encryption algorithms will transform a human interpretable text block or information in to a non-interpretable block of symbols. The objective of any such encryption algorithm will be making the cipher block more non-interpretable and seemingly random block of symbols. So any cipher block will always be random and will purely be a set of random permutations of symbols. The efforts of distinguis...