The Evolution of Hash Functions

Vocabulary flashcards covering the concepts, algorithms, entities, and vulnerabilities discussed in the lecture notes on hash functions and secure storage.

Hash Function

An algorithm that converts data of any size into a unique, fixed-size value (digest) that cannot be decrypted, used to determine data integrity and support authentication.

Non-repudiation

The security concept stating that the authenticity and origin of information cannot be denied.

Digest

A small, fixed-size value of letters and numbers produced by a hash function to represent input data of any size.

Hash Table

A data structure used by computers to store and reference hash values as a fast, secure, and efficient way to look up data.

Bit

The smallest unit of data measurement on a computer that represents user input as either a $0$ or a $1$.

Message Digest 5 (MD5)

An early hash function created in the early 1990s that converts data into a $128\text{-bit}$ value, displayed in a hash table as a string of $32$ characters.

Ronald Rivest

A professor from the Massachusetts Institute of Technology (MIT) who developed the MD5 hashing algorithm in the early 1990s to verify file integrity over networks.

Hash Collision

An event that occurs when two different inputs produce the exact same output hash value due to mapping infinite possible inputs into a finite set of outputs.

Collision Attack

A cyberattack where threat actors exploit hash collisions to fraudulently impersonate authentic data.

Secure Hashing Algorithms (SHAs)

A family of hash functions approved by NIST that generate longer digests to resist collision attacks.

National Institute of Standards and Technology (NIST)

The organization that reviews and approves each algorithm in the Secure Hashing Algorithm (SHA) family.

SHA-1

An algorithm in the SHA family that produces a $160\text{-bit}$ digest and is no longer considered collision-resistant.

SHA Family Algorithms

The five cryptographic functions approved by NIST: SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512.

Rainbow Table

A file containing pre-computed hash values mapped to their corresponding plaintext inputs, used by attackers like a dictionary to crack hashed passwords.

Salt

A random string of characters added to plaintext data before hashing to generate a unique hash value and defeat rainbow table attacks.

Salting

A security practice of appending or prepending a random string of characters to sensitive data before it is hashed to ensure identical inputs yield different hash outputs.