1.3.1: compression, encryption and hashing

• What name is given to the public and private keys used in asymmetric encryption?

  key pair
• Name the two categories of compression

  lossy and lossless
• In which type of compression is the quality of a file not degraded?

  lossless
• What is the purpose of encryption?


  To keep data secure during transmission
• Name one type of lossless compression

  • Run length encoding
  • Dictionary encoding
• In which form of encryption do the sender and receiver share the same private key?

  Symmetric encryption
• How many keys are used in asymmetric encryption?

  two (one public and one private)
• If person A wants to send a message to person B using asymmetric encryption, which key should they use to encrypt the message?

  A: A’s public key B: A’s private key C: B’s public key D: B’s private key
• If person A wants to send a message to person B using asymmetric encryption, which key should they use to encrypt the message?

  C: B’s public key A message encrypted with B’s public key can only be decrypted with B’s private key, which only B has access to
• What is said to have occurred when two keys map to the same hash?

  a collision
• In which kind of lossless compression are repeated characters replaced by one occurrence and the number of times to repeat the character?

  run length encoding
• What name is given to the process of turning an input into a fixed size value?

  hashing
• Which data structure uses hashing to store information with constant lookup time?

  hash table
• What is meant by compression?

  The process of reducing the space required to store a file
• Name two properties that a hashing algorithm should have

  • Quick to calculate
  • Output smaller than input
  • Low chance of collision