Asymmetric Algorithms 6.2

Question 1

Diffie-Hellman Key Exchange

Answer 1

A key exchange method over an insecure communication channel. It does not itself encrypt or authenticate. It’s an anonymous key-agreement protocol. It’s the same symmetric key generation system that we’ve seen before. Take someone’s public key, combine it with a private key, and you end up with a symmetric key.

Question 2

Rivest, Shamir, Adelman (RSA)

Answer 2

The first practical public-key cryptography system. Encrypt, decrypt, digital signatures. Based on the product of two large prime numbers. You must know the factors to decode. It’s now in the public domain and used extensively for web site encryption and digital rights management.

Question 3

Digital Signature Algorithm (DSA)

Answer 3

A modification of Diffie-Hellman for digital signatures. Also part of Federal Information Processing Standard (FIPS). Combine with elliptic curve cryptography to create Elliptic Curve Cryptography Digital Signature Algorithm (ECDSA). Fast efficient digital signatures.

Question 4

Elliptic Curve Cryptography (ECC)

Answer 4

Used for encryption, digital signatures, pseudo-random generators and more. The keys are smaller which is advantageous for mobile devices because it requires less CPU cycles, and thus, less battery power.

Question 5

Pretty Good Privacy (PGP)

Answer 5

Commercial software owned by Symantec. There is now an open standard called OpenPGP (RFC 4880). It’s implemented as software called GNU Privacy Guard (GPG). Available for many OS’s. Good for email day-to-day encryption.

Question 6

Diffie-Hellman Ephemeral (DHE)

Answer 6

Variant of DH Key Exchange. Simply uses an ephemeral key to preform key exchange.

Question 7

Elliptic Curve Diffie Hellman Ephemeral (ECDHE)

Answer 7

Elliptic curve variant of DH using an ephemeral key.