I'm looking for an authoritative reference about the history of salts in the context of hash functions. Why is the personalization string in a hash function called a "salt"? Who should be credited with introducing this technique?
So far I have found:
- Plenty of speculative folk etymology on the Wikipedia discussion page for salt
- The earliest academic reference to salt I can find is Password Security: A Case Study by Robert Morris & Ken Thompson, from 1979.
- According to the source code at the UNIX Heritage Society, salted passwords seemed to be added in V7 UNIX, released in 1979 (
passwd.c: V7 vs V6). The source code already refers to the technique as salt, in its use of variable names. Was this the first use of the salt technique anywhere?