Nuts and Bolts of Encryption: A Primer for Policymakers, Edward W. Felten, Center for Information Technology Policy. Department of Computer Science, Woodrow Wilson School of Public and International Affairs, Princeton University, version of February 20, 2017. An up-to-date version of this paper will be available at https://www.cs.princeton.edu/~felten/encryptionprimer.pdf

“This paper offers a straight for ward introduction to encryption, as it is implemented in modern systems, at a level of detail suitable for policy discussions. No prior background on encryption or data security is assumed. Encryption is used in two main scenarios. Encrypted storage allows information to be stored on a device, with encryption protecting the data should a malicious party get access to the device. Encrypted communication allows information to be transmitted from one party to another party, often across a network, with encryption protecting the data should a malicious party get access to the data while it is in transit. Encryption is used somewhat differently in these two scenarios, so it makes sense to present them separately. We’ll discuss encrypted storage first, because it is simpler. We emphasize that the approaches described here are not detailed description s of any particular existing system, but rather generic descriptions of how state-of-the-art systems typically operate. Specific products and standards fill in the details differently, but they are roughly similar at the level of detail given here.”