Read "Keys Under Doormats: Mandating Insecurity by Requiring Government Access to all Data and Communications" by Abelson et al. This paper is different from many of the papers that we've read in 6.1800 in that it's largegly about policy, not specific technical content.

This paper talks a lot about encryption, which you'll see in Lectures 23 and 24. When a user encrypts a piece of data, they do so with an encryption key. The resulting output is encrypted data that cannot be read by anyone else unless they have the corresponding decryption key. In the case of symmetric-key encryption, the same key is used for encryption and decrypting.

If we're using public keys for encryption, though, it works as follows: if Alice wants to send a message to Bob, she encrypts the message with Bob's public key, and Bob will be able to decrypt with his secret key. Notice, then, that anyone can encrypt a message to Bob, because everyone knows his public key ("public" really means public here: known by everyone). But only Bob can reverse the operation (by decrypting). This is the same way you will see public-key cryptography used in Lecture 24, as part of Tor.

Incidentally, in Lecture 23, you will see public-key cryptography used for signatures, where Alice signs a message with her secret key, which Bob can then verify with Alice's public key. In this paper, most of the references are about using public-key cryptography for encryption, not signatures.

As you read, think about the following:

• The paper states that "complexity is the enemy of security." What examples from 6.1800 have you seen that illustrate this idea?
• Suppose our systems did grant exceptional access to law enforcement agencies. How would you be impacted? In what ways?
• Who else would be impacted by this decision? In what ways would they be impacted? You should be able to give far more than one example; give at least three here.

Submit your answers to these questions on Canvas by 12:00pm on Friday 4/24. You should be writing a few sentences in response to each question (so we don't need you to write an essay for each one, but we're also expecting more than one-word answers). Your responses should be in your own words, not direct quotations from the paper.