Before the
modern era, cryptography was concerned solely with message confidentiality
(i.e., encryption)—conversion of messages from a comprehensible form into an
incomprehensible one and back again at the other end, rendering it unreadable
by interceptors or eavesdroppers without secret knowledge (namely the key
needed for decryption of that message).

attempted to ensure secrecy in communications, such as those of spies, military
leaders, and diplomats. In recent decades, the field has expanded beyond
confidentiality concerns to include techniques for message integrity checking,
sender/receiver identity authentication, digital signatures, interactive proofs
and secure computation, among others.

Below, you
will find the declassified FBI File that was labeled “Cryptography.”

The file
stretches back to the mid to late 1930s! It is an ongoing FOIA request,
wherein many documents have not been released yet, and are being reviewed by
multiple agencies. I will continue to add the releases, as they become

Federal Bureau of Investigation (FBI) Release

Bureau of Investigation (FBI) Release, October 19, 2016
[356 Pages,