Announcing the first SHA1 collision

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Mattias Geniar, February 23, 2017

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Granted, it took over 6.500 years of CPU computation and 110 years of GPU computation to get the first SHA1 collision, but it’s possible.

For the tech community, our findings emphasize the necessity of sunsetting SHA-1 usage. Google has advocated the deprecation of SHA-1 for many years, particularly when it comes to signing TLS certificates. As early as 2014, the Chrome team announced that they would gradually phase out using SHA-1. We hope our practical attack on SHA-1 will cement that the protocol should no longer be considered secure.

We hope that our practical attack against SHA-1 will finally convince the industry that it is urgent to move to safer alternatives such as SHA-256.

Source: Google Online Security Blog: Announcing the first SHA1 collision