This book constitutes the thoroughly refereed post-workshop proceedings of the 6th International Workshop on the Arithmetic of Finite Field, WAIFI 2016, held in Ghent, Belgium, in July 2016. The 14 revised full papers and 3 invited talks presented were carefully reviewed and selected from 38 submissions. The papers are organized in topical sections on invited talks; elliptic curves; applications; irreducible polynomials; applications to cryptography; Boolean functions; cryptography; cryptography and Boolean functions.