This book investigates proofs of correctness of realistic security protocols in a formal intuitive setting. The protocols examined include Kerberos versions smartcard protocols non-repudiation protocols and certified email protocols. The method of analysis the Inductive Method in the theorem prover Isabelle turns out to be both powerful and flexible. This book advances significant extensions to the method of analysis and presents novel and illuminating findings on the protocols analyzed. This book will benefit researchers and graduate students in the fields of formal methods information security inductive methods and networking.