This paper presents horizontal and vertical side channel analysis techniques for an implementation of the McEliece cryptosystem. The target of this side-channel attack is a state-of-the-art field-programmable gate array (FPGA) implementation of the efficient quasi-cyclic moderate-density parity-check McEliece decryption operation, as presented at Design, Automation and Test in Europe (DATE) 2014. The presented cryptanalysis succeeds to recover the complete secret key after a few observed decryptions. It consists of a combination of a differential leakage analysis during the syndrome computation followed by an algebraic step that exploits the relation between the public key and the private key.

This paper describes the attacks on a secure group communication with hierarchical access control, which arises in the communication group involving users with different privilege levels. The basic idea is to enable each subgroup to read the messages of those subgroups that are located at a lower level in the hierarchy. For such a setting, the Chinese remainder theorem based hierarchical access control scheme CRTHACS is proposed, which also aims at hiding the underlying hierarchy. Here we describe practical attacks, which allow for revealing at least parts of the hierarchy.

Generalizing a construction of Silverman (1999), we describe a redundant representation of finite fields GF(qn), where computations in GF(qn) are realized through computations in a suitable residue class algebra. Our focus is on fields of characteristic ≠ 2 and we show that the representation discussed here can, in particular, be used for designing a highly regular multiplication circuit for GF qn).

For original article see G. Drolet, ibid., vol. 47, no. 9, p. 938-946, (Sept 1998). We characterize the smallest n with GF(2)[X]/(X/sup n/ + 1) containing an isomorphic copy of GF(2/sup m/). This characterization shows that the representation of finite fields described in a previous issue of the IEEE Transactions on Computers is not "optimal" as claimed. The representation considered there can often be improved significantly.

An attack on the public key cryptosystem Polly Cracker is described, that reveals the complete secret key /spl sigma/ /spl isin/ F/sub q//sup n/ by means of n (nonadaptively) chosen "fake" ciphertexts.