# Google Online Security Blog: Announcing the first SHA1 collision

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

- Host: [security.googleblog.com](https://links.thingelstad.xyz/hosts/security.googleblog.com/)
- Saved: February 24, 2017 (2017-02-25T04:28:24Z)
- Record: https://links.thingelstad.xyz/links/8a18ed4980d9/
- JSON: https://links.thingelstad.xyz/links/8a18ed4980d9.json

## What Jamie wrote

Today, more than 20 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. We’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.

## Facts

- Kind: [Page](https://links.thingelstad.xyz/kinds/page/)

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## Elsewhere

- Wayback Machine: https://web.archive.org/web/*/https://security.googleblog.com/2017/02/announcing-first-sha1-collision.html