Patent ID: 7760986

Claim:
A method of authentication of data to be sent in a digital transmission system, wherein the data is organized in a hierarchical structure comprising a series of data units, comprising: generating a first authentication value for at least one first unit, wherein the at least one first unit comprises an identifier of a first key and a first signature value generated using the first key; storing said first authentication value in a second unit, wherein the second unit is a subdirectory hierarchically above the at least one first unit; generating a second authentication value for said second unit, wherein the second authentication value is a hash value, and wherein the second authentication value authenticates the first authentication value stored in the second unit; generating a second signature value for at least the second authentication value using a second key; and transmitting the hierarchical structure comprising said at least one first unit and the second unit, the first and second authentication values, an identifier for the second key, and the second signature value as digital data in a digital transmission system.