SHA-0
More info
- Creator
- NSA
- Released
- 1993
- Type
- Cryptographic hash function
- Successor
- SHA-1
The original Secure Hash Algorithm, published in 1993 and withdrawn two years later without explanation.
It was simply called SHA and published as FIPS 180. In 1995 it was replaced by SHA-1, which differed in a single detail: a one-bit rotation in the message schedule. The NSA gave no reason, and only when cryptographers started attacking the original did it become clear how much that small tweak was worth.
Florent Chabaud and Antoine Joux described a theoretical collision attack in 1998. In 2004 Joux and colleagues produced an actual collision after roughly 80,000 CPU hours, and Xiaoyun Wang's group soon shortened the path further. The same techniques were then turned on SHA-1, eventually leading to SHAttered. The NSA had been right all along — it just never said why.