Patent ID: 7298840

Claim:
A method of authenticating data, the method comprising the steps of: receiving a message and a corresponding first data item generated according to a first predetermined rule; generating a second data item according to a second predetermined rule on the basis of the received message; calculating a first distance between the received first data item and the generated second data item; comparing the calculated first distance with a predetermined distance; and processing the message by accepting the message if the calculated first distance is smaller than the predetermined distance value wherein the step of processing the message includes: generating a first sequence of message sections from the message, each message section having a predetermined length; modifying at least a first message section of the sequence of message sections; applying at least a first permutation to at least the modified first message section of the sequence of message sections; calculating at least one XOR sum of a result of at least the first permutation; and calculating a hash value from the calculated at least one XOR sum.