This book constitutes the refereed post-proceedings of three workshops heldat the 20th International Conference on Financial Cryptography and DataSecurity, FC 2016, in Bridgetown, Barbados, in February 2016. The 22 full papers presented were carefully reviewed and selected from 49 submissions. They feature the outcome of the Third Workshop on Bitcoin and Blockchain Research, BITCOIN 2016, the First Workshop on Advances in Secure Electronic Voting Schemes, VOTING 2016, and the 4th Workshop on EncryptedComputing and Applied Homomorphic Cryptography, WAHC 2016.