Blown to Bits Chapter 5 pages 21-36 Answers

Questions corresponding to pages 21-36:

1. What is the Data Encryption Standard (DES)?
   • Data Encryption Standard is an encryption standard "adopted as a national standard in the 1970s and is widely used in the worlds of business and finance. It has pretty much survived all attempts at cracking, although the inexorable progress of Moore's Law has made exhaustive searching all possible keys more feasible in recent years."
2. What is Advanced Encryption Standard (AES)?
   • "A newer standard was adopted in 2002 after a thorough and public review. It is precisely because these encryption methods are so widely known that confidence in them can be high. They have been subjected to both professional analysis and amateur experimentation, and no serious deficiencies have been discovered."
3. What is public key cryptography?
   • "A way for Alice and Bob, without any prior arrangement, to agree on a secret key, known only to the two of them, by using messages between them that are not secret at all." "It is the invention that made electronic commerce possible."
   • a.) One way computation? (just the general concept)
     • "a computation with two important properties: It can be done quickly, but it can't be undone quickly. To be more precise, the computation quickly combines two numbers x and y to produce a third number."
   • b.) Public key encryption?
     • "anyone can send encrypted mail to anyone over an insecure, publicly exposed communication path."
   • c.) Digital signatures?
     • A protocol that "marks a public message in such a way that anyone can easily verify that the mark is [the sender's] and no one can forge it."
   • d.) What is the RSA algorithm?
     • The Rivest-Shamir-Adleman algorithm is "a practical digital signature scheme [that] can be used for confidential messaging. With RSA, each person generates a pair of keys - a public key and a secret key. The public and private keys are inverses: If you transform a value with a, then transforming the result with A recovers the original value. If you transform a value with A, then transforming the result with a recovers the original value."
   • e.) With a digital signature, what is a certificate?
     • A sender "goes to a trusted authority, to which she presents her public key together with her proof of her identity. The authority digitally signs her key - producing a signed key called a certificate."
   • f.) What are certification authorities?
     • "Organizations that issue certificates"
4. How do we know we are involved in an encrypted web transaction?
   • When we use a website with a URL that begins with "https"
5. What were the crypto wars about?
   • The Clinton administration pushed for the communications industry to create encryption products that had back doors - "an extra key held by the government, which would let law enforcement and intelligence agencies decrypt the phone communication."
6. Who is Phil Zimmerman?
   • "a journeyman programmer and civil libertarian who had been interested in cryptography since his youth. …He created an encryption software for the people, to counter the threat of increased government surveillance. … He named it PGP for 'Pretty Good Privacy.'"
7. Why isn't all email encrypted? (HINT: 3 reasons)
   1. "there is still little awareness of how easily our email can be captured as the packets flow through the Internet."Passwords give an illusion of security
   2. "there is little concern because more ordinary citizens feel they have little to hide, so why would anyone bother looking?"
   3. "encrypted email is not built into the Internet infrastructure in the way encrypted web browsing is. You have to use nonstandard software, and the people you communicate with have to use some compatible software. In commercial settings, companies may not want to make encryption easy for office workers."
8. What is the international ECHELON system?
   • "a cooperative project of the U.S. and several of its allies, and is the descendant of communications intelligence systems from the time of the Second World War. It automatically monitors data communications to and from satellites that relay Internet traffic."
9. BIG PICTURE QUESTION TO PONDER: "As encryption becomes as ordinary a tool for personal messages as it already is for commercial transactions, will the benefits to personal privacy, free expression, and human liberty outweigh the costs to law enforcement and national intelligence, whose capacity to eavesdrop and wiretap will be at an end?" (p. 36)