Pub. online:6 May 2020Type:Research ArticleOpen Access
Journal:Informatica
Volume 31, Issue 2 (2020), pp. 277–298
Abstract
The vulnerable part of communications between user and server is the poor authentication level at the user’s side. For example, in e-banking systems for user authentication are used passwords that can be lost or swindled by a person maliciously impersonating bank.
To increase the security of e-banking system users should be supplied by the elements of public key infrastructure (PKI) but not necessary to the extent of standard requirements which are too complicated for ordinary users.
In this paper, we propose two versions of authenticated key agreement protocol (AKAP) which can be simply realized on the user’s side. AKAP is a collection of cryptographic functions having provable security properties.
It is proved that AKAP1 is secure against active adversary under discrete logarithm assumption when formulated certain conditions hold. AKAP2 provides user’s anonymity against eavesdropping adversary. The partial security of AKAP2 is investigated which relies on the security of asymmetric encryption function.
Journal:Informatica
Volume 15, Issue 2 (2004), pp. 251–270
Abstract
A new digital signature scheme in non‐commutative Gaussian monoid is presented. Two algebraic structures are employed: Gaussian monoid and a certain module being compatible with a monoid. For both monoid and module, presentation and action level attributes are defined. Monoid action level is defined as monoid element (word) action on module element as an operator. A module is a set of functions (elements) with special properties and could be treated as some generalization of vector space.
Signature scheme is based on the one‐way functions (OWF) design using: three recognized hard problems in monoid presentation level, one postulated hard problem in monoid action level and one provable hard problem in module action level.
For signature creation and verification the word equivalence problem is solved in monoid action level thus avoiding solving it in monoid presentation level. Then the three recognized hard problems in monoid presentation level can be essentially as hard as possible to increase signature security. Thus they do not influence on the word problem complexity and, consequently, on the complexity of signature realization.
The investigation of signature scheme security against four kind of attacks is presented. It is shown that the signature has a provable security property with respect to the list of attacks presented here, which are postulated to be complete.