2.3 encryption

• Purpose of encryption

  - Encryption is the transformation of data from one form to another to prevent an unauthorised third party being able to unerstand it
• How is the data unreadable?

  The origional data or message is known as plaintext and the encrypted data is known as ciphertext
• What is needed to unscramble the text?

  The encryption method or algorithm is known as the cipher and the data needed to lock or unlock the message is known as the key
• Examples of methods of encrytion

  There are many methods of encryption, with the most well known being the very basic Caesar Cipher and the perfectly secure Vernam Cipher
• Symmetric encryption

  A technique for encrypting data where the same key is used to both encrypt and decrypt data.
• Asymmetric encryption


  - uses two keys: a public key known to everyone and a private or secret key known only to the recipient.

  
  

  - matching pairs are generated by an encryption algorithm ( private and public keys)

  
  

  - (mathematically linked but can't be derived from one another)

  
  

  - A message encrypted with a public key can be decrypted only with the same algorithm used by the public key and requires the recipient's private key, too. Anyone intercepting the message cannot decrypt it because he or she does not have the private key.
• Example of Asymmetric encryption

  If 'A' wants to send confidential document to 'B'

  
  

  1) 'B' send 'A' their public key who uses it to encrypt the document before sending it to 'B'

  
  

  2) 'B' uses private key to decrypt the document