Late 1970s - Unix: salting

Salting "does not increase the task of finding any individual password, starting from scratch, but now the work of testing a given character string against a large collection of encrypted passwords has been multiplied by 4096 (212)."
With uniform distribution, there are ~3740 unique salts in 10,000 password file entries

"it becomes impractical to prepare an encrypted dictionary in advance."

"It becomes nearly impossible to find out whether a person with passwords on two or more systems has used the same password on all of them"