Basically, our approach characterizes a pattern into a key value, which is used in codebook search. The key value is generated using a centroid method for each vector (block). It represents the angle of a line where the pixel values in the block are distributed with respect to. If the key value is equal to 45 degrees, it implies that the values of the pixels in a block are symmetrically distrib...

The notion of key generators is introduced to symmetric cryptography. Key generators help eliminate the dependence of a block cipher’s security on a single, static key. If one of the dynamic keys is leaked to the adversary, then this compromise does not reveal future keys and prior keys used by the block cipher to encrypt distinct blocks of plaintext. A practical, key generator updating algorit...

In this paper, we formalize an attack scheme using the key-dependent property, called key-dependent attack. In this attack, the intermediate value, whose distribution is key-dependent, is considered. The attack determines whether a key is right by conducting statistical hypothesis test of the intermediate value. The time and data complexity of the key-dependent attack is also discussed. We also...

Image denoising by block matching and threedimensionaltransform filtering (BM3D) is a two steps state-ofthe-art algorithm that uses the redundancy of similar blocks innoisy image for removing noise. Similar blocks which can havesome overlap are found by a block matching method and groupedto make 3-D blocks for 3-D transform filtering. In this paper wepropose a new block grouping algorithm in th...

Strong cryptographic algorithms have been used for securing data communication. It is considered as one of the best tools to help people to protect their sensitive information from cryptanalysts when it is stored or transmitted via insecure communication channels. In this paper we present a novel symmetric-key block ciphering algorithm, MJEA (for Modified Jamal Encryption Algorithm). MJEA has a...

The FEAL N cryptosystem has been developed by N T T as a highly programming e cient block cipher system as it does not use look up tables It was rst presented in It is essentially an N round Feistel block cipher operating on bit blocks and determined by a bit key FEAL is the standard block cipher but N T T intend that FEAL can be used in cipher block chaining mode when plaintexts are not reveal...

Humankind has grown phenomenally from Stone Age to information technology age. Information technology is deeply treasured; mainly because of the Internet. The internet has brought great changes in almost every domain of life. Besides a computer, laptop, Desktop, even a Mobile Phones, I-Pad, IPod have the facility to use the Internet. With the Internet, life has become easier to get things done ...

We present two block cipher distinguishers in a setting where the attacker knows the key. One is a distinguisher for AES reduced the seven rounds. The second is a distinguisher for a class of Feistel ciphers with seven rounds. This setting is quite different from traditional settings. We present an open problem: the definition of a new notion of security that covers attacks like the ones we pre...

In this paper, we propose an efficient watermarking scheme for H.264/SVC, where the watermarking is performed by using a block-based approach. The embedding process of watermark in the proposed scheme is performed in the encoder of H.264/SVC. The blocks for watermarking embedding are selected by considering both the length of the watermark signal and the size of the input video frame. The water...

In this thesis, new ideas in cryptography, cryptanalysis and designing high speed secure applications are presented. The Advanced Encryption Standard (AES) is used to demonstrate these ideas. In the eld of cryptography, new encryption models are proposed. In the eld of cryptanalysis, a secure key schedule for AES is presented together with new generalized attacks. These generalized attacks are ...