Most of the devices in the Internet of Things will be battery powered sensor devices. All the operations done on battery powered devices require minimum computation. Secure algorithms like RSA become useless in the Internet of Things environment. Elliptic curve based cryptography emerges as a best solution for this problem because it provides higher security in smaller key size compare to RSA. This book focuses on the use of Elliptic Curve Cryptography with different authentication architectures and authentication schemes using various security algorithms. It also includes a review of the math required for security and understanding Elliptic Curve Cryptography.