Cipher

/ˈsɪfər/

noun — "a method for transforming information to conceal its meaning."

A Cipher is a systematic technique used to encode information, transforming readable plaintext into an obscured or encrypted form known as ciphertext, with the intent of preventing unauthorized access or understanding. Ciphers form the backbone of cryptography, enabling secure communication, data protection, and authentication across digital and analog systems. The term emphasizes the algorithmic or procedural method applied to the information rather than the message itself.

File Encryption Key

/ˌɛf iː ˈkeɪ/

noun — "file encryption key."

FEK, short for File Encryption Key, is a symmetric cryptographic key used to encrypt and decrypt the contents of a single file within systems like EFS. Each file protected by a filesystem-level encryption mechanism typically has its own unique FEK to ensure isolation and minimize the risk of large-scale data compromise if one key is exposed.

Encrypting File System

/ˌiː ɛf ˈɛs/

noun — "encrypted file storage system."

EFS, short for Encrypting File System, is a filesystem-level encryption technology that allows individual files or directories to be transparently encrypted on storage volumes. It integrates directly with the operating system’s file management layer, providing confidentiality for sensitive data while maintaining standard access semantics for authorized users.

Cipher-based Message Authentication Code

/siː-mæk/

noun — "the cryptographic signature that proves a message hasn’t been tampered with."

CMAC, short for Cipher-based Message Authentication Code, is a cryptographic algorithm used to verify the integrity and authenticity of messages. It generates a fixed-size tag from a variable-length message using a block cipher, such as AES, ensuring that any alteration in the message can be detected.

Hash function

/hæʃ ˈfʌŋk.ʃən/

noun — "a function that converts data into a fixed-size digital fingerprint."

Hash Function is a mathematical algorithm that transforms input data of arbitrary length into a fixed-size value, called a hash or digest. This process is deterministic, meaning the same input always produces the same hash, but even a tiny change in input drastically changes the output. Hash Functions are widely used in data integrity verification, cryptography, digital signatures, password storage, and blockchain technologies.

Cryptography

/ˈkrɪp.təˌɡræ.fi/

noun — "the art and science of keeping information secret and verifiable."

Cryptography is the study and practice of techniques for securing communication and data from unauthorized access, manipulation, or interception. It involves transforming readable data (plaintext) into an encoded form (ciphertext) using mathematical algorithms and keys, ensuring confidentiality, integrity, authentication, and non-repudiation. Cryptography underpins secure digital communication, online banking, blockchain systems, and password protection.

AEAD

/ˈiː-ɛe-dɛd/

n. “Encrypt it — and prove nobody touched it.”

AEAD, short for Authenticated Encryption with Associated Data, is a class of cryptographic constructions designed to solve two problems at the same time: confidentiality and integrity. It ensures that data is kept secret and that any unauthorized modification of that data is reliably detected.

Poly1305

/ˌpɒliˈwʌn-θɜːrtiː-fʌɪv/

n. “A tiny guardian watching every bit.”

Poly1305 is a cryptographic message authentication code (MAC) algorithm created by Daniel J. Bernstein, designed to verify the integrity and authenticity of a message. Unlike encryption algorithms that hide the content, Poly1305 ensures that data has not been tampered with, acting as a digital seal that can detect even a single-bit change in a message.

ChaCha20

/ˈtʃɑː-tʃɑː-twɛn-ti/

n. “Fast. Portable. Secure — even when the hardware isn’t helping.”

ChaCha20 is a modern stream cipher designed to encrypt data quickly and securely across a wide range of systems, especially those without specialized cryptographic hardware. Created by Daniel J. Bernstein as a refinement of the earlier ChaCha family, ChaCha20 exists to solve a practical problem that older ciphers struggled with: how to deliver strong encryption that remains fast, predictable, and resistant to side-channel attacks on ordinary CPUs.