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Abstract. T-function is a relatively new cryptographic building block suitable for streamciphers. It has the potential of becoming a substitute for LFSRs, and those that correspond to maximum length LFSRs are called single cycle T-functions. We present a family of single cycle T-functions, previously unknown. An attempt at building a hardware oriented streamcipher based on this new T-function is given.

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Abstract. Camellia is a 128 bit block cipher proposed by NTT and Mitsubishi. We discuss the security of Camellia against the square attack. We find a 4 round distinguisher and construct a basic square attack. We can attack 5 round Camellia by guessing one byte subkey and using 2 16 chosen plaintexts. Cosidering the key schdule, we may extend this attack up to 9 round Camellia including the first FL/FL −1 function layer.

Abstract. At PKC 2003 Paeng, Jung, and Ha proposed a lattice based public key cryptosystem(PJH). It is originated from GGH, and designed as a hybrid of GGH and NTRUEncrypt in order to reduce the key size. They claimed that PJH is secure against all possible attacks, especially against lattice attacks. However, in this paper, we present a key recovery attack, based on lattice theory, against PJH. The running time of our attack is drastically short. For example, we could recover all secret keys within 10 minutes even for the system with n = 1001 on a single PC. Unlike other lattice attacks against NTRUEncrypt and GGH, the attack may be applied well to the system with much larger parameters. We present some clues why we believe so. Based on this belief, we declare that PJH should not be used in practice.

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We present a true random number generator (TRNG) using dark noise of a CMOS image sensor. Because the proposed TRNG is based on the dark characteristics of the CMOS image sensor, it does not require any additional hardware, such as light source and optics, for providing true randomness. Therefore, it can be a promising solution for compact and low-cost mobile application. By using NIST SP 800-90B entropy assessment suite, we evaluate the min-entropy for the raw outputs of our original noise source and the final random numbers including post-processing as well. We also adopt NIST SP 800-22 statistical randomness test suite for the evaluation of the random numbers. The test results demonstrate that the generated random numbers pass all the statistical tests and have high entropy. INDEX TERMS Random number generation, CMOS image sensors, dark current.

In this paper, we introduce a new class of PRSGs, called partitioned pseudorandom sequence generators(PPRSGs), and propose an RFID authentication protocol using a PPRSG, called S-protocol. Since most existing stream ciphers can be regarded as secure PPRSGs, and stream ciphers outperform other types of symmetric key primitives such as block ciphers and hash functions in terms of power, performance and gate size, S-protocol is expected to be suitable for use in highly constrained environments such as RFID systems. We present a formal proof that guarantees resistance of S-protocol to desynchronization and tag-impersonation attacks. Specifically, we reduce the availability of S-protocol to pseudorandomness of the underlying PPRSG, and the security of the protocol to the availability. Finally, we give a modification of S-protocol, called S * -protocol, that provides mutual authentication of tag and reader.