Abstract:


BAP: Broadcast Authentication Using Cryptographic 
Puzzles

Patrick Schaller and Srdjan Capkun and David Basin



We present two broadcast authentication protocols 
based on delayed key disclosure. Our protocols rely 
on symmetric-key cryptographic primitives and use 
cryptographic puzzles to provide efficient broadcast 
authentication in different application scenarios, 
including those with resource-constrained wireless 
devices such as sensor nodes. The strong points of 
the protocols proposed are that one protocol allows 
instantaneous message origin authentication, whereas 
the other has low communication overhead. In addition 
to formalizing and analyzing these specific protocols, 
we carry out a general analysis of broadcast 
authentication protocols based on delayed key disclosure. 
This analysis uncovers fundamental limitations of this 
class of protocols in terms of the required accuracy of 
message propagation time estimations, if the protocols 
are to guarantee security and run efficiently.