Cipher Types Quiz

Cipher Types

• Bifid Cipher: A grid matching letters to numerical values. More complex versions use 5x5 matrices.
• Playfair Cipher: A 5x5 grid using a secret phrase. Letters cannot repeat in the grid, J is substituted with I.
• Homophonic Substitution Cipher: Replaces plaintext with multiple possible ciphertexts.
• Caesar Coding: Shifts each letter 3 places in the alphabet.
• Scrambled Alphabet Cipher: Randomly maps alphabet letters. Cracked using frequency analysis.
• Vigenère Cipher: Uses multiple cipher alphabets. Commonly uses a code word. Cracked via Kasiski examination.
• Morse Code: Translates characters into dots and dashes using electronic current pulses.
• Fractionated Morse Cipher: Provides an extra layer of encryption to standard Morse Code with a key mapping.
• Pig Pen Cipher: A mono-alphabetic substitution method using a grid pattern.
• Rail Fence Cipher: A method where the message is written in a sequence across a number of rails.
• Combinations: Selects items from a larger set without considering order.
• Permutations: Arranges objects in a specific order.
• One-Time Pad (OTP): A nearly uncrackable cipher using a unique codebook.

Data and Information

• Data: Computers store data as binary (1s and 0s). ASCII supports 256 characters. UTF-16 extends characters to 65,536 values.
• Hexadecimal: Splits a bit stream into groups of four bits (0-15).
• Date Integrity: CRC (Cyclic Redundancy Check) verifies data reliability up to 95.5% accuracy. CRC-32 is a common method.
• Reed Solomon: A data integrity scheme that not only detects but also corrects errors.
• Huffman Coding: Compresses data by identifying common patterns in binary data or metadata.
• Lempel-Ziv Welsh (LZW): An adaptive dictionary-based compression technique.
• Little Endian: Stores the least significant byte in the lowest memory address.
• Big Endian: Stores the most significant byte in the lowest memory address.

Cryptographic Concepts

• Integers: Positive, negative, no fraction parts.
• Rational Numbers: Fractions.
• Real Numbers: Include integers and rational numbers (e.g., 2.3).
• Prime Numbers: Integers divisible only by 1 and themselves.
• Natural Numbers: Positive integers.

Additional Cryptographic Methods and Concepts

• XOR, OR, AND: Logical operations (detailed in Shawn's Study Guide).
• Mod Operator: Calculates the remainder of an integer division.
• Monoalphabetic Cipher: A type of substitution cipher where each letter is consistently replaced by the same letter in the ciphertext.
• Polyalphabetic Cipher: A substitution cipher that uses multiple alphabets to encrypt the plaintext.
• Enigma Cipher Machine: Used a polyalphabetic substitution cipher with a secret key and did not repeat with a reasonable amount of time.
• Asymmetric Encryption: Uses two keys (public and private) for encryption and decryption.
• Symmetric Encryption: Uses a single key to both encrypt and decrypt.
• Frequency Analysis: A technique to analyze ciphertext by determining the frequency of letters or other patterns and matching it to known frequencies in standard English.
• Diffie-Hellman Key Exchange: Asymmetric algorithm for setting up symmetric encryption.

Cryptographic Concepts(continued)

• Perfect Forward Secrecy: New session keys are used to encrypt communication for each session.
• Electronic Code Book (ECB): Encrypts each block using the same key and makes blocks independent of other blocks in the ciphertext. This leads to vulnerabilities with same plaintext blocks and repeated ciphertext.
• Cipher Block Chaining (CBC): Uses an initialization vector (IV) to encrypt the first block. The output of the encryption is XORed with the next block. This makes each block depends on the previous block.
• Cipher Feedback (CFB): A self-synchronizing stream cipher, XORs data with the outputs of the encryption process for each block.
• Output Feedback (OFB): Converts a block cipher to a synchronous stream cipher. Generates a counter value and a nonce to encrypt and then XOR with the plaintext block
• Cipher Modes: CTR (Counter) The non-ce value is used to XOR with the plaintext block in order to encrypt the plaintext to ciphertext.

Additional Cryptographic Methods and Concepts(continued)

• Padding: Methods to ensure plaintext messages fit into fixed-size blocks (used in block ciphers).
• DES: A 64-bit block cipher with 56-bit key size.
• 3DES: Uses two or three executions of the DES algorithm.
• Entropy: Measure of unpredictability in a key.
• Encryption/Decryption: Process of converting plaintext to ciphertext/ciphertext to plaintext.
• Encoding/Decoding: Processes used to convert data from one form to another.
• AES: A 128-bit block cipher used for symmetric encryption (has 10,12,14 rounds).
• IDEA: A 64-bit block cipher used for symmetric encryption with more than 17 rounds.
• RC2, RC5, RC6: Various stream ciphers.
• Skipjack: A 64-bit block cipher used for symmetric encryption applications.

Additional Cryptographic Methods and Concepts (continued)

• Hashing: Provides integrity checks, creating unique fingerprints for data (hash value). MD5, SHA, SHA-2 are common hashing algorithms.
• Hash Collisions: When two different inputs produce the same hash signature.
• Pre-Image Attack: Finding an input that produces a specific hash output.
• Birthday Attack: A brute-force attack based on the probability of finding collisions.
• Known Plaintext Attack: An attacker knows parts of the ciphertext and the corresponding plaintext.
• Chosen Ciphertext Attack: An attacker sends a message to the target encrypted with the target's public key and analyzes the message.
• Active Attack: An attacker inserts or modifies messages.
• Reply Attack: An attacker takes a valid message and re-sends it to the system.
• Light-Weight Cryptography: Suitable for resource-constrained devices.
• Bitcoin (BTC)/Ethereum: Use blockchain and peer-to-peer networks.
• WEP, WEP+TKIP, WPA , WPA2: Wired Equivalent Privacy and Wi-Fi Protected Access protocols for wireless security. Includes block size, key sizes, IV sizes, and used methods.
• Cryptographic Cracking: Exhaustive search using brute force to decrypt.

PKI and Related Concepts

• PKI: Public Key Infrastructure holds public keys for trusted parties.
• Public Key/Private Key: Public key is widely distributed, used for encryption. Private key is kept secret, used for decryption.
• PKCS: Standards for password-based encryption, signing, and certificates in PKI.
• Certificate Authority (CA): Issues, manages, and verifies digital certificates in PKI. Creates hierarchical trust relations
• Hashing algorithm: MD5, SHA, SHA-2

Other Security Concepts

• Salt: Random characters added to passwords before hashing to prevent attacks.
• Bcrypt: Hashing algorithm for generating password hashes with salt.
• Rainbow Table Attack: Offline attack mapping hashed values to original values.
• HMAC: Message Authentication Code that ensures message integrity and authentication
• APR1: Hashing algorithm for generating password hashes.
• LDAP: Management of user credentials and access policies. Centralized management.
• PHPass: PHP library for secure password hashing and storage.
• PBKDF2: Password-Based Key Derivation Function 2 that generates stronger passwords from a given password and salt

Other Security Concepts (continued)

• Non-cryptographic Hash: Fast hash functions run on various platforms, useful for situations where cryptographic hashes are too computationally expensive. This creates hashes for data integrity, but without encryption it is prone to vulnerabilities.
• CBC-MAC: Counter with Cipher block chaining, message authentication code, increases security.
• AES-CCM: Counter mode with Cipher block chaining to increase security
• Windows Hashing
• Linux Hashing

Test your knowledge on various cipher types, including Bifid, Playfair, and Vigenère ciphers. This quiz covers the fundamental principles and mechanisms behind these encryption methods. Challenge yourself and see how well you understand classical and modern ciphers.