This report outlines the talks presented at the winter school on Hash3: Proofs, Analysis, and Implementation, ECRYPT II Event on Hash Functions. In general, speakers may not write everything what they talk on the slides. So, this report also outlines such findings following the understanding of the author of this report. The author of this report would like to disclaim that any mistakes in this report are solely due to author of this report as not all of the technical details are verified with the speakers. The findings presented in this report are solely due to the author’s understanding of the talks at the winter school. For many of the talks, the author of this report has spent some time in understanding some technical details (using prior knowledge and (re)visiting the literature) and explained that in this report. Of course, not all the details are covered while exploring the literature.