Non-degrading erasure-tolerant information authentication with an application to multicast stream authentication over lossy channels

Abstract

The concept of erasure-tolerant information authentication was recently introduced to study an unconditionally secure setting where it is allowed to lose a limited number of message letters during transmission. Even if a part of the message is lost, the verifier will still be able to check the authenticity of some or all of the received message letters. In general, there might be some letters whose authenticity cannot be verified although they have arrived at the recipient’s side. These letters will be discarded. We consider a special case when the verifier can always check the authenticity of all received message letters. This property is desirable since no data will be lost due to the verifier’s inability to verify its authenticity (i.e., the scheme does not introduce additional degradation of the quality of the received information). We provide necessary and sufficient conditions for a set system based erasure-tolerant authentication scheme to be non-degrading. We also discuss efficient implementations and propose a provably secure stream authentication scheme that makes use of erasure-tolerant authentication codes.