CryptoScan: A Secured Scan Chain Architecture

Abstract

Scan based testing is a powerful and popular test technique. However the scan chain can be used by an attacker to decipher the cryptogram. The present paper shows such a side-channel attack on LFSR-based stream ciphers using scan chains. The paper subsequently discusses a strategy to build the scan chains in a tree based pattern with a selfchecking compactor. It has been shown that such a structure prevents such scan based attacks but does not compromise on fault coverage.