1960s to early 1970s: plaintext password storage Early time-sharing systems CTSS "one afternoon [...] any user who logged in found that instead of the usual message-of-the-day typing out on his terminal, he had the entire file of user passwords" Fernando J. Corbato, "On Building Systems That Will Fail", 1991 (Turing Award Lecture) (The problem was a text editor temporary file collision, "early 60's" to "1965" by different sources.) TENEX had a character-by-character timing leak exacerbated by paging "The UNIX system was first implemented with a password file that contained the actual passwords of all the users" Robert Morris and Ken Thompson, "Password Security: A Case History", 1978 Besides, some typewriters would print the password being typed unless manually prevented from doing so.