Journal: First SHA1 Collision

Today, 10 years after of SHA-1 was first introduced, we are announcing the first practical technique for generating a collision. This represents the culmination of two years of research that sprung from a collaboration between the CWI Institute in Amsterdam and Google. Weâ(TM)ve summarized how we went about generating a collision below. As a proof of the attack, we are releasing two PDFs that have identical SHA-1 hashes but different content.

https://security.googleblog.com/2017/02/announcing-first-sha1-collision.html