This book constitutes the refereed proceedings of three workshops held at the 19th International Conference on Financial Cryptography and Data Security, FC 2015, in San Juan, Puerto Rico, in January 2015. The 22 full papers presented were carefully reviewed and selected from 39 submissions. They feature the outcome of the Second Workshop on Bitcoin Research, BITCOIN 2015, the Third Workshop on Encrypted Computing and Applied Homomorphic Cryptography, WAHC 2015, and the First Workshop on Wearable Security and Privacy, Wearable 2015.