Encryption
No description yet. This curated deck is ready for daily study.
Card preview (12)
Describe what is meant by ‘encryption’.
The process of converting data into a format that cannot be understood by an unauthorised viewer, unless you have access to the key needed to decrypt it (conversion of plaintext into ciphertext)
What is meant by ‘plaintext’?
Plaintext describes the original unencrypted text
What is the need for encrypting data?
To protect the data’s confidentiality
Give examples of two forms of encryption.
• Symmetric encryption • Asymmetric encryption
Describe the difference between symmetric and asymmetric encryption.
• Symmetric uses the same key to encrypt and decrypt the data • Asymmetric uses two different keys - public key to encrypt the data and a private key, which only the recipient knows, to decrypt it
Describe how a Caesar cipher works.
Realigns the alphabet, substituting each letter of the original message with a letter further down the alphabet (systematic shift, all letters affected in the same way)
(Exam-style question) Explain one reason why the Caesar cipher is a weak encryption algorithm. (2)
The number of keys are limited, making it easy to use brute force to decrypt
(Exam-style question)
State: • Yes Justification: • Each letter is represented • The symbol is a unique representation
(Exam-style question) Give the key used in the first stage of the encryption process. (1)
5
(Exam-style question) Give the ciphertext that is produced by this Rail Fence cipher encryption algorithm.
TIHYSEMNEEERNA
On a Vigenere square, what axes do the plaintext and the keyword go on?
• Plaintext - x-axis • Keyword - y-axis
In regard to a Vigenere cipher, what is a keystream?
A version of the keyword that is repeated over and over