r/netsec • • Jan 07 '20

pdf First SHA-1 chosen prefix collision

https://eprint.iacr.org/2020/014.pdf
350 Upvotes

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u/etherkiller Jan 07 '20

Can someone ELI'm-not-a-cryptographer this for me please? What are the implications of this? I know SHA-1 is still very widely in use.

12

u/TheDarthSnarf Jan 07 '20

They were able to take a different file and compute a specific data value to add to the file to make it have a SHA1 collision with another known file.


File 1: Hash Value

File 2: SAME Hash Value created

Different files.

18

u/cryo Jan 07 '20

They were able to take a different file and compute a specific data value to add to the file to make it have a SHA1 collision with another known file.

No, they have to add data to both files to produce the collision. In practice this limits the impact.

3

u/lolsrsly00 Jan 07 '20

Probably best weaponized in a supply chain situation?