Questions and Answers
What does 'plaintext' refer to?
What is 'ciphertext'?
What is a cipher?
Algorithm for transforming plaintext to ciphertext
What is a key in cryptography?
Signup and view all the answers
What does encipher/encrypt mean?
Signup and view all the answers
What does decipher mean?
Signup and view all the answers
What is cryptography?
Signup and view all the answers
What is cryptoanalysis?
Signup and view all the answers
What does cryptology encompass?
Signup and view all the answers
What are the requirements for a symmetric cipher?
Signup and view all the answers
What is the objective of cryptoanalysis?
Signup and view all the answers
What are the two types of attacks used in cryptoanalysis?
Signup and view all the answers
What are the features of a cryptanalytic attack?
Signup and view all the answers
What does ciphertext only mean?
Signup and view all the answers
What is known plaintext?
Signup and view all the answers
What does chosen plaintext mean?
Signup and view all the answers
What is chosen ciphertext?
Signup and view all the answers
What does chosen text mean?
Signup and view all the answers
What is a brute-force search?
Signup and view all the answers
What are the two basic building blocks of all encryption techniques?
Signup and view all the answers
What are classical substitution ciphers?
Signup and view all the answers
What is a Caesar cipher?
Signup and view all the answers
What is a monoalphabetic cipher?
Signup and view all the answers
What is Playfair encryption?
Signup and view all the answers
What is a multiletter substitution cipher?
Signup and view all the answers
What are transposition ciphers?
Signup and view all the answers
What are transposition/permutation ciphers?
Signup and view all the answers
What are row transposition ciphers?
Signup and view all the answers
What is the Hill cipher?
Signup and view all the answers
Study Notes
Key Concepts in Classic Encryption
- Plaintext: The original message before encryption.
- Ciphertext: The coded version of the plaintext after encryption.
- Cipher: An algorithm designed to transform plaintext into ciphertext.
- Key: A unique piece of information used in a cipher, known only to the sender and receiver.
Encryption and Decryption Processes
- Encipher/Encrypt: The process of converting plaintext into ciphertext.
- Decipher: The reverse process, transforming ciphertext back into plaintext.
Fields of Study
- Cryptography: The science of encoding messages to maintain confidentiality.
- Cryptoanalysis: The study aimed at deciphering ciphertext without needing the key.
- Cryptology: The overarching field that combines both cryptography and cryptoanalysis.
Symmetric Ciphers Requirements
- Requires a strong encryption algorithm and a secret key shared only between sender and receiver.
- Assumes the encryption algorithm is publicly known.
- Secure channels are necessary for key distribution.
- Mathematical relationship exists where Y = EK(X) and X = DK(Y).
Objectives and Attacks in Cryptoanalysis
- Objective: To recover the key used for encryption rather than the original message.
- Types of Attacks: Cryptanalytic and brute-force attacks.
- Cryptanalytic Attack Features: Based on known ciphertext, plaintext, chosen plaintext, or chosen ciphertext.
Types of Knowledge in Attacks
- Ciphertext only: Knowing the encryption algorithm and ciphertext; relies on statistical analysis.
- Known plaintext: Possessing both suspected plaintext and corresponding ciphertext.
- Chosen plaintext: Picking specific plaintext to obtain the corresponding ciphertext.
- Chosen ciphertext: Similar to chosen plaintext, used to gather ciphertext from selected plaintext.
- Chosen text: Involves selecting plaintext or ciphertext for encrypting/decrypting purposes.
Brute-Force Search
- The method of systematically testing every possible key to decode the ciphertext into intelligible plaintext.
Basic Components of Encryption Techniques
- Substitution: Replacing plaintext characters or bit patterns with ciphertext characters or bit patterns.
- Transposition: Rearranging the order of characters in the plaintext without changing the actual letters.
Classical Ciphers
- Caesar Cipher: A rotational cipher with 26 possible shifts, susceptible to brute-force attacks.
- Monoalphabetic Cipher: Jumbles the letters randomly, providing 26 unique keys for encryption.
- Playfair Encryption: Uses a 5x5 grid to substitute letters, omitting one character from the alphabet.
- Multiletter Substitution Cipher: Substitutes m plaintext letters with m ciphertext letters, exemplified by the Hill Cipher.
Transposition Ciphers
- Employ letter rearrangement to obscure the message.
- Row Transposition Ciphers: Write plaintext in rows across a specified number of columns, then reorder the columns based on a key before reading the rows.
Advanced Example
- Hill Cipher: Uses matrix mathematics in the encryption process, encapsulating complex relationships between plaintext, ciphertext, and keys.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge of classic encryption terms with these flashcards. Each card provides a key term related to encryption along with its definition to help reinforce your understanding of the subject. Perfect for students learning about cryptography.