Cryptography

1. What is an important difference between public key cryptography and secret key cryptography?

Public key cryptography or Asymmetric key
• Based on the concept of a key pair
• The key pair is designated and associated to one, and only one, trading partner
• Each half of the pair (one key) can encrypt information that only the other half (one key) can decrypt
Secret key Cryptography or Symmetric-key algorithms
• Identical keys are used to encrypt and decrypt the message
• A message encrypted by one specific symmetric key can only be decrypted by using the same key, it can be decrypted with a different key

2. What kinds of Information do Echelon Collects?

Echelon apparently collects different data in several ways. Reports suggest it has massive ground based radio antennae to intercept satellite transmissions. In addition, some sites reputedly are tasked with tapping surface traffic
Echelon uses numerous satellites to catch "spillover" data from transmissions between cities. These satellites then beam the information down to processing centers on the ground.
Echelon also routinely intercepts Internet transmissions. The organization allegedly has installed numerous "sniffer" devices. These "sniffers" collect information from data packets as they traverse the Internet via several key junctions. It also uses search software to scan for web sites that may be of interest.
Furthermore, it is believed that Echelon has even used special underwater devices which tap into cables that carry phone calls across the seas. According to published reports, American divers were able to install surveillance devices on to the underwater cables. One of these taps was discovered in 1982, but other devices apparently continued to function undetected.
It is not known at this point whether Echelon has been able to tap fiber optic phone cables.

3. Describe at least three different kinds of uses of encryption that has a social value. Indicate why they are important.

The Social implication of Encryption are:
• Data Security -By transforming information to unreadable form confidential information tends to be secured to anyone.
• Knowledge -By translating of readable message to a secret code which tends other people will not understand to read and must need special knowledge to decrypt.
• Incomprehensible - People that don’t understand tends to be discouraged from reading or copying the messages.