This book presents the use of tweakable block ciphers for lightweight authenticated encryption, especially applications targeted toward hardware acceleration where such efficient schemes have demonstrated competitive performance and strong provable security with large margins. The first part of the book describes and analyzes the hardware implementation aspects of state-of-the-art tweakable block cipher-based mode ΘCB3. With this approach, a framework for studying a class of tweakable block cipher-based schemes is developed and two family of authenticated encryption algorithms are designed for the lightweight standardization project initiated by the National Institute of Standards and Technology (NIST): Romulus and Remus. The Romulus family is a finalist for standardization and targets a wide range of applications and performance trade-offs which will prove interesting to engineers, hardware designers, and students who work in symmetric key cryptography.