# When was hash chain first used?

Hash linking is used to prove the integrity of a blockchain, or similar systems. When was that technique first used? I would guess it was early, maybe 1950s/1960s?

Lamport suggested the use of hash chaining in 1981 in Password Authentication with Insecure Communication, Communications of the ACM 24.11 (November 1981), pp 770-772.

He cites 3 prior papers:

1. Diffie, W., and Hellman, M.E. New directions in cryptography. IEEE Trans. Inform. Theory 1T-22 (Nov. 1976), 644-654.

2. Evans, A., Kantrowitz, W., and Weiss, E. A user authentication scheme not requiring secrecy in the computer. Comm. A CM 17, 8 (Aug. 1974), 437-442.

3. Wilkes, M.V. Time-Sharing Computer Systems. American Elsevier, New York, 1972.

[1] is the paper which essentially invented Public Key Cryptography in the open literature. Lamport refers to the use of a one way function F, as described there, as hash functions in his chain.

[2] and [3] are cited for "the widespread use of such a function", e.g., storing $$y=F(x)$$ instead of $$x$$.

So it seems to me Lamport may well be the first to suggest the use hash chaining.

Edit: Thanks to @Gilles for pointing out Merkle patented hash trees in 1979.

• Merkle patented hash trees in 1979, and hash chains are a special case of that. I don't know if that special case had been used before. Mar 25, 2019 at 23:18
• what about this reference that appears here and there, "In January 1953, Hans Peter Luhn wrote an internal IBM memorandum that used hashing with chaining. " Mar 27, 2019 at 7:51
• Interesting, but fid you forget a link/reference? Is it maybe for storage (hashing with chaining is such a method) with a well distributed hash which is in general not one way? Mar 27, 2019 at 7:57
• In fact, it's in my answer to another question on general hashing. crypto.stackexchange.com/questions/56404/… Mar 27, 2019 at 8:03