| Explain the functionality of a substtution caesar cipher | Letters are randomly replaced |
| What 2 types of encryption methods should you be familiar with? | Caesar and Vernam |
| Define encryption | The process of scrambling data so that it cannot be understood if intercepted in order to keep it secure during transmission |
| What is meant by the term plaintext | unencrypted information |
| What is meant by the term ciphertext | result of encryption performed on plaintext |
| What is meant by the term cipher | an algorithm for performing encryption or decryption |
| Explain the functionality of a shift caesar cipher | All the letters in the albabet are shifted by the same amount |
| Why are caesar ciphers so easily cracked? | Once you discover just one character, a shift cipher can be completely cracked
The frequency at which each character occurs can
provide a clue as to which letter has been replaced with which, e.g. 'E' is the most common in english langauge |
| What must you know in order to decrypt ciphertext | The encryption method used and the key |
| What are the two types of Caesar ciphers you need to be aware of? | Shift and substituion |
| Explain the term 'a one-time pad' for a cipher | each key is only ever be used once |
| What requirements for the key does a Verman cipher have | Random
One time pad
At least as long as the plaintext |
| How does a Verman cipher work? | 1. Aligning the characters of the plaintext and the key
2. Converting each character of both the key and the plaintext to binary
3. Applying a logical XOR operation to the bit
patterns
4. Converting the result back to a character |
| How is a Verman cipher considered completely secure? | Since the key used with a Vernam cipher is chosen at random, the ciphertext is also
random |
| Explain the functionality of a substtution caesar cipher | Letters are randomly replaced |
