Experimental Study of DIGIPASS GO3 and the Security of Authentication. Based on the analysis of 6digit onetime passwords(OTP) generated by DIGIPASS GO3 we were able to reconstruct the synchronisation system of the token, the OTP generating algorithm and the verification protocol in details essential for an attack. The OTPs are more predictable than expected. A forgery attack is described. We argue the attack success probability is 85. That is much higher than 106 which may be expected if all the digits are independent and uniformly distributed. Under natural assumptions even in a relatively small bank or company with 104 customers the number of compromised accounts during a year may be more than 100.

IVP: A Three Level ConfusionDiffusion Network Supporting Implicit Data Integrity We present a cryptographic construction called IVP and study its security properties. IVP is a three level confusiondiffusion network that supports confidentiality and data integrity without requiring any message expansion of the content, such as, for example, for the computation of a MAC. We demonstrate that IVP is in the recently proposed class of cryptographic constructions called xe2x80x98Random Oracles according to Observer functionsxe2x80x99 (RO2). These constructions support a new notion of data integrity called xe2x80x98implicitxe2x80x99 data integrity, which is based on the fact that user data usually demonstrate some patterns. If some ciphertext becomes corrupted, then the resulting plaintext no longer demonstrates such patterns. Thus, defense against data corruption attacks becomes possible by hardening the computation of ciphertext values, the plaintext of which demonstrates patterns. The encryption key is considered unknown.We show that IVP supports implicit data integrity and is secure in input perturbing and oracle replacing adversary models. The security of IVP is associated with a pattern which is frequently encountered among client and server data. This is the pattern of encountering 4 or more 16bit words being equal to each other in a set of 32 words. The cryptographic strength of IVP is 30.215 bits, which is sufficient for defending against online data corruption and content replay attacks. Computationally, IVP is much lighter than other authenticated encryption approaches requiring only two additional rounds of AES, beyond the AES standard encryption rounds in the critical path. These correspond to some minimal computation overhead.