Hoffmann, Max, and Christof Paar. “Stealthy Opaque Predicates in Hardware - Obfuscating Constant Expressions at Negligible Overhead”. IACR Transactions on Cryptographic Hardware and Embedded Systems, vol. 2018, no. 2, May 2018, pp. 277-9, doi:10.13154/tches.v2018.i2.277-297.