DACS 2201 / 06-Basic Cryptography

Vocabulary flashcards covering basic cryptography terminology, classic and modern algorithms, hashing, and security principles from the DACS 2201 lecture.

Cryptography

Scrambling data so it cannot be read or understood; it transforms information into an unintelligible form so unauthorized persons cannot access it.

Steganography

The practice of hiding the existence of data, such as embedding hidden messages in unused portions of image, audio, or video files.

Metadata

Data used to describe the content or structure of the actual data.

Encryption

The process of changing original text into a secret message using cryptography.

Decryption

The process of changing a secret message back to its original form.

Plaintext

Unencrypted data that is to be encrypted or the output produced by a decryption process.

Ciphertext

The scrambled and unreadable output produced by the process of encryption.

Cleartext

Data that is stored or transmitted without any encryption.

Cipher

A cryptographic algorithm that takes plaintext data as input and transforms it into ciphertext using procedures based on mathematical formulas.

Key

A value used by a cryptographic algorithm to produce ciphertext; if one is used to encrypt, the reverse process also uses one to decrypt.

Kerckhoff’s Principle

The principle stating that only the key and not the algorithm should be secret.

Substitution

A technique in cryptography where one letter is substituted with another.

Transposition

A technique in cryptography where the order of letters in the message is rearranged.

Caesar Cipher

One of the oldest known keyed substitution algorithms, attributed to Julius Caesar, typically using a key of $3$ to shift alphabet positions.

ROT-13 Cipher

A specific Caesar cipher where the key is set to $13$, causing a rotatation of the alphabet by $13$ positions.

Pigpen Cipher

A keyless substitution cipher used by the Freemasons where letters are substituted by symbols enclosing them in a specific figure.

Vigenère Cipher

A substitution cipher that generalizes the Caesar cipher by using a password as a key instead of a single number.

Rail Fence Cipher

Also called the Zig-Zag Cipher; a simple transposition algorithm that places successive letters vertically into key lines following a zig-zag pattern.

Stream Cipher

A modern cryptographic algorithm that takes one character at a time and replaces it with another.

Block Cipher

A modern cryptographic algorithm that manipulates an entire block of plaintext at once, such as blocks of $8$ or $16$ bytes.

Sponge Function

A function that takes a string of any length as input and returns a string of any requested variable length.

Hash Algorithm

An algorithm that takes a set of data (string or file) as input and returns a unique string as output, often called a message digest.

Collision Resistant

A characteristic of a secure hash algorithm where it produces a unique output for every different input.

Digital Fingerprint

Another term for a hash output (message digest) because it is unique and used for comparison and integrity verification.

MD5

The most well-known Message Digest (MD) hash algorithm; it is no longer considered suitable for use due to weaknesses.

SHA-2

A Secure Hash Algorithm currently considered secure, including versions such as SHA-256, SHA-384, and SHA-512.

SHA-3

A new hash standard announced in $2015$ that is suitable for low-power devices like sensors and IoT devices.

RIPEMD

Race Integrity Primitives Evaluation Message Digest; a hash algorithm whose primary feature is two independent parallel chains of computation.

Symmetric Cryptographic Algorithm

An algorithm that uses the same key to encrypt and decrypt a document; also known as private key cryptography.

AES

Advanced Encryption Standard; a symmetric block cipher that performs three steps on every block of $128$ bits with no known attacks.

Blowfish

A symmetric block cipher with no known attacks.

Asymmetric Algorithms

Also known as Public Key Cryptography; algorithms that use mathematically related key pairs (one public and one private) to solve the problem of key distribution.

RSA

Rivest, Shamir, and Adleman algorithm; one of the oldest asymmetric algorithms that uses prime numbers to generate key pairs.

ECC

Elliptic Curve Cryptography; an asymmetric algorithm that uses smaller key sizes than RSA, resulting in faster computation and lower power consumption.

DSA

Digital Signature Algorithm; an asymmetric algorithm used to create digital signatures to electronically verify a sender.

Key Exchange Algorithms

Methods that enable two parties to agree on a common secret key over an insecure medium for use in symmetric cryptography.

Diffie-Hellman (DH)

A key exchange method where parties agree on a large prime number and a related integer to separately compute the same secret key.

Perfect Forward Secrecy

A system that generates random public keys that are different for each session, ensuring that if a secret key is compromised, only one message is revealed.

Confidentiality

A data protection state ensuring that only authorized parties can view the data.

Integrity

A data protection state ensuring information is correct and has not been altered.

Authentication

A data protection state ensuring the identity of the sender can be verified.

Nonrepudiation

The inability to deny that a user performed a specific action.

Obfuscation

The practice of making something obscure or unclear to others to protect data.