Improved Cryptographic Protection of Information using Robust Authentication Algorithms

Information is typically transmitted in telecommunication systems in form of messages. Many applications nowadays demand protection of their content and/or authentication of the sender and recipient of the message. Message Authentication Codes are commonly used for the authentication purposes. They are very sensitive to any change of the message they are appended to. If one or more bits of the message change, Message Authentication Codes change about 50% of their bits, making the message useless. A successful verification of Message Authentication Codes demands that all of bits of the received Message Authentication Code and of the bits of the recalculated Message Authentication Code from the received message are equal. Such a hard condition is not suitable for some applications. The introduction of a softer condition for the successful verification can improve the successful authentication of messages corrupted by transmission over a noisy channel. Algorithms are presented, which introduce robustness into the verification of messages protected by Message Authentication Codes, as well as an algorithm which not only verifies, but also corrects the messages corrupted due to the noisy channel.