En studie av zero knowledge-identifikationsprotokoll för smarta kort
Zero knowledge protocols is a lesser known type of protocol that can be used for identification. These protocols are especially designed not to reveal any information during an identification process that can be misused later on, neither by the one who should be convinced of the identity of the user, nor by anyone else that is eavesdropping. Many of these protocols are also especially designed for implementation in smart cards. The more common type of card with a magnetic stripe has during the last few years become more susceptible to attacks since they are easily copied. Smart cards combined with a secure identification protocol has been predicted to be the solution to this problem. Zero knowledge protocols are one of several types of protocols that can be used for this purpose. In this thesis a number of zero knowledge protocols are examined that have been presented since the introduction of the concept in the 1980's. In addition to the protocol descriptions information is also given about how to choose parameter values, and what progress and discoveries have been made concerning the security of the protocols. Some assumptions that are easy to overlook in an implementation are also highlighted, and an evaluation of the protocol performances is made. The conclusion is that zero knowledge protocols are both efficient and adaptable, while they at the same time provide high security. Because of this it may not be necessary to compromise between these properties even for simpler types of smart cards.