Cryptography Glossary

Browse 125 cryptography terms defined in plain English, from the cultural dictionary of computing.

125 Cryptography Terms

AES
Advanced Encryption Standard, a widely used symmetric encryption algorithm standardized for securing data at rest and in transit. AES became the dominant...
AES-256
AES using a 256-bit key, commonly cited as a high-strength symmetric encryption configuration for protecting sensitive data. The algorithm remains AES; the 256...
AES-GCM
A mode of operation for AES that provides both confidentiality and integrity through authenticated encryption, using Galois/Counter Mode. It is common in...
API Key Rotation
API Key Rotation is an API-focused security concern involving how interfaces are authenticated, limited, or protected from misuse. Security teams use it to...
Asymmetric Encryption
Asymmetric Encryption is cryptographic protection for asymmetric data so unauthorized parties cannot read it easily. Security teams use it to enforce trust,...
Asymmetric Key
One half of a public/private key pair used in asymmetric cryptography, where the public key can be shared and the private key remains secret. Asymmetric keys...
Attribute-Based Encryption
A form of encryption in which decryption depends on satisfying a policy expressed over attributes rather than simply possessing one conventional key. It...
Block Cipher
Block Cipher is a symmetric cryptographic primitive that encrypts fixed-size blocks of data under a shared secret key. Security teams use it to enforce trust,...
Blowfish
A symmetric block cipher designed by Bruce Schneier in the 1990s, historically popular as a fast general-purpose encryption algorithm. While still notable in...
Brute Force
Brute Force is an attack method that systematically tries every possible combination of a password, encryption key, or other secret value until the correct one...
Cache Timing Attack
A side-channel attack that infers sensitive information by measuring timing differences caused by CPU cache behavior during secret-dependent operations. It is...
Challenge-Response
Challenge-Response is an authentication pattern in which a verifier sends a nonce or challenge and validates a computed response. Security teams use it to...
Cipher Block Chaining
A block-cipher mode of operation in which each plaintext block is combined with the previous ciphertext block before encryption, commonly shortened to CBC. It...
Cipher Suite
Cipher Suite is the negotiated set of cryptographic algorithms and parameters used by a secure communication session. Security teams use it to enforce trust,...
Ciphertext
Ciphertext is data after encryption, represented in a form intended to be unreadable without the right key and algorithm context. Security teams use it to...
Ciphertext Feedback
A block-cipher mode that turns a block cipher into a self-synchronizing stream-like cipher by feeding prior ciphertext into subsequent encryption steps,...
Cleartext
Cleartext is data stored or transmitted in readable form without cryptographic protection against observation. Security teams use it to enforce trust, reduce...
Client-Side Encryption
Client-Side Encryption is cryptographic protection for client-side data so unauthorized parties cannot read it easily. Security teams use it to enforce trust,...
Collision Resistance
A property of a cryptographic hash function meaning it should be computationally infeasible to find two different inputs that produce the same output. Strong...
Cryptanalysis
Cryptanalysis is the study of how to break or weaken cryptographic systems by exploiting mathematical or implementation flaws. Security teams use it to enforce...
Crypto Agility
Crypto Agility is the ability to replace algorithms, key sizes, or protocol settings without redesigning the whole system. Security teams use it to enforce...
Cryptographic Algorithm
A formal algorithm used for encryption, hashing, digital signatures, key agreement, or related cryptographic purposes. Security depends not only on choosing a...
Cryptographic Hash
Cryptographic Hash is a one-way function that maps arbitrary input to a fixed-size digest used for integrity and indexing. Security teams use it to enforce...
Cryptographic Key
A secret or semi-public value used by a cryptographic algorithm to encrypt, decrypt, sign, verify, or derive other secrets. Key management quality often...
Cryptographic Nonce
Cryptographic Nonce is a value intended to be unique per operation so cryptographic protocols can prevent replay and key-stream reuse. Security teams use it to...
Cryptographic Primitive
Cryptographic Primitive is a low-level building block such as a cipher, hash, MAC, or signature algorithm used inside larger protocols. Security teams use it...
Cryptographic Protocol
A protocol that uses cryptographic operations to achieve goals such as confidentiality, authentication, key exchange, or integrity. Even strong primitives can...
Cryptojacking Attack
Cryptojacking Attack is an attack technique in which an adversary abuses victim compute resources to mine cryptocurrency without authorization. Defenders...
Crypto Library
A software library that implements cryptographic primitives and protocols such as hashing, signing, encryption, key exchange, or certificate handling. Crypto...
Crypto Module
A code module or hardware-backed component dedicated to cryptographic operations such as key management, encryption, decryption, signing, or verification....
Data at Rest Encryption
Data at Rest Encryption is cryptographic protection for data at rest data so unauthorized parties cannot read it easily. Security teams use it to enforce...
Data Encryption Standard
Data Encryption Standard is the historical symmetric cipher standard based on DES, now retained mainly for legacy context. Security teams use it to enforce...
Data in Transit Encryption
Data in Transit Encryption is cryptographic protection for data in transit data so unauthorized parties cannot read it easily. Security teams use it to enforce...
Decryption
The process of converting ciphertext back into readable plaintext using the correct key and algorithm. If decryption is possible for an attacker,...
Decryption Key
The cryptographic key used to convert ciphertext into plaintext, either directly in symmetric systems or as the private component in appropriate asymmetric...
DES
DES is an older symmetric block cipher with a 56-bit key that is now considered insecure against practical brute force. Security teams use it to enforce trust,...
Digital Signature
A cryptographic scheme that proves a message was created by a known sender (authentication) and wasn't altered in transit (integrity). The signer hashes the...
Elliptic Curve Cryptography
Elliptic Curve Cryptography is public-key cryptography based on elliptic-curve groups that offers strong security with relatively small keys. Security teams...
Encryption
Encryption is the process of converting readable data (plaintext) into an unreadable format (ciphertext) using a mathematical algorithm and a cryptographic...
Encryption Key Management
Encryption Key Management is the generation, storage, rotation, distribution, archival, and destruction of cryptographic keys. Security teams use it to enforce...
Entropy Analysis
Entropy Analysis is the measurement of randomness or predictability in data to spot weak secrets, packed code, or anomalous content. Security teams use it to...
Envelope Encryption
Envelope Encryption is a pattern where a data key encrypts content and that data key is itself encrypted by a master key. Security teams use it to enforce...
Ephemeral Key
Ephemeral Key is a short-lived cryptographic key generated for a session or transaction rather than long-term reuse. Security teams use it to enforce trust,...
Forward Secrecy
Forward Secrecy is the property that compromise of a long-term private key does not expose past session plaintext. Security teams use it to enforce trust,...
GnuPG
GnuPG is an open-source implementation of OpenPGP used for encryption, signing, and key management workflows. Security teams use it to enforce trust, reduce...
Hardware Security Module
Hardware Security Module is a tamper-resistant device used to generate, store, and use cryptographic keys under strong controls. Security teams use it to...
Hash
A fixed-size output produced by a hash function from arbitrary input data. Cryptographic hashes are one-way (irreversible), deterministic, and...
Hash Collision
Hash Collision is a cryptographic mechanism or concept used to protect confidentiality, integrity, authenticity, or trust establishment. Security teams use it...
Hash Extension Attack
Hash Extension Attack is an attack technique in which an adversary abuses length-extension properties in certain hash constructions to forge authenticated...
Hashing
Hashing is the process of transforming input data of any size into a fixed-size output (called a hash, digest, or fingerprint) using a mathematical function...
HMAC
Hash-based Message Authentication Code — a construction that combines a cryptographic hash function with a secret key to produce a message authentication code....
HMAC Authentication
HMAC Authentication is message authentication based on a keyed hash so a receiver can verify integrity and shared-secret knowledge. Security teams use it to...
Homomorphic Encryption
An encryption scheme that allows computation on encrypted data without decrypting it first — the result, when decrypted, matches the result of performing the...
HSM
Short for hardware security module, a dedicated device or service designed to generate, store, and use cryptographic keys inside tamper-resistant hardware....
Hybrid Encryption
Hybrid Encryption is a design that combines public-key cryptography for key exchange with symmetric encryption for data transfer. Security teams use it to...
IV
Short for initialization vector, a non-secret value used with certain encryption modes to ensure the same plaintext does not always produce the same...
JSON Web Encryption
JSON Web Encryption is the JOSE standard for encrypting claims or structured content into a compact token format. Security teams use it to enforce trust,...
JSON Web Key
JSON Web Key is the JOSE data format used to represent public, private, or symmetric keys in JSON. Security teams use it to enforce trust, reduce exposure,...
Key Agreement
Key Agreement is a cryptographic method that lets parties derive a shared secret without sending that secret directly. Security teams use it to enforce trust,...
Key Ceremony
Key Ceremony is a formal process for generating and handling high-value cryptographic keys under strict procedural controls. Security teams use it to enforce...
Key Custodian
A person or role formally responsible for safeguarding cryptographic keys or key material and enforcing the procedures around their handling. Key custodians...
Key Derivation
Key Derivation is the process of deriving one or more cryptographic keys from a secret and contextual input. Security teams use it to enforce trust, reduce...
Key Derivation Function
A function that derives one or more cryptographic keys from a secret value (password, passphrase). Password-hashing KDFs (bcrypt, scrypt, Argon2) are...
Key Escrow
Key Escrow is an arrangement in which decryption keys are held by a trusted third party under defined recovery conditions. Security teams use it to enforce...
Key Exchange
Key Exchange is the protocol step through which parties establish shared keying material for secure communication. Security teams use it to enforce trust,...
Key Length
The size of a cryptographic key, usually measured in bits, which influences the search space an attacker would face in brute-force attempts. Key length...
Key Management
Key Management is the full lifecycle handling of cryptographic keys from generation through rotation, storage, use, and destruction. Security teams use it to...
Key Pair
Key Pair is the related public and private keys used in asymmetric cryptography for encryption, signatures, or key exchange. Security teams use it to enforce...
Key Recovery
The process of restoring access to encrypted data or services by recovering a lost, escrowed, backed-up, or split cryptographic key. Key recovery procedures...
Key Rotation
Key Rotation is the scheduled or event-driven replacement of cryptographic keys and secrets to reduce long-term exposure. Security teams use it to enforce...
Key Size
The nominal size of a cryptographic key in bits, often used as a quick measure of brute-force resistance for a given algorithm. Key size is closely related to...
Key Stretching
Key Stretching is the deliberate increase of computational cost when deriving keys from passwords to slow offline guessing. Security teams use it to enforce...
Keystroke Injection
Keystroke Injection is an attack technique in which an adversary emulates keyboard input to execute commands or alter a target system. Defenders analyze it to...
Key Wrapping
The protection of one cryptographic key by encrypting it with another key, typically for storage, transport, or hierarchical key management. Key wrapping is...
Lightweight Cryptography
Cryptographic algorithms and designs optimized for constrained environments such as small microcontrollers, sensors, tags, and battery-powered devices with...
Master Key
A high-value cryptographic key used to protect, derive, or wrap other keys rather than directly encrypting ordinary application data. Because many lower-level...
MD5
MD5 is a legacy cryptographic hash function that is fast but broken for collision resistance and unsuitable for secure integrity checks. Security teams use it...
Message Authentication Code
Message Authentication Code is a keyed cryptographic check that proves message integrity and shared-secret possession. Security teams use it to enforce trust,...
Message Digest
A fixed-length hash value computed from input data and used to detect changes, compare content, or support cryptographic protocols. The term appears both...
Null Cipher
A cipher or negotiated mode that applies no real encryption to data even though the surrounding protocol may still look like it is using a cryptographic...
Offline Attack
An attack performed without ongoing interaction with the target system, typically after obtaining data such as password hashes, encrypted files, or captured...
OpenPGP
An open standard for encrypting and signing data with public-key cryptography, commonly used for secure email, file encryption, and key distribution. OpenPGP...
OpenSSL
OpenSSL is a widely used cryptographic library and TLS toolkit for certificates, keys, and secure transport. Security teams use it to enforce trust, reduce...
Padding Oracle Attack
A cryptographic attack that abuses padding error responses to gradually decrypt or forge ciphertext. It shows up in application security, identity,...
Password Hash
A cryptographic concept related to password hash, secure communication, key handling, or trust establishment. It shows up in application security, identity,...
Password Hashing
The practice of transforming a plaintext password into an irreversible, fixed-length digest using a deliberately slow, salted algorithm — such as bcrypt,...
PBKDF2
A password-based key derivation function that repeatedly hashes input with a salt to slow offline cracking. It shows up in application security, identity,...
Pem File
A text-based container format commonly used to store certificates, private keys, and related cryptographic material. It shows up in application security,...
Perfect Forward Secrecy
A cryptographic property where compromise of a long-term key does not expose previously captured session traffic. It shows up in application security,...
PFS
Short for perfect forward secrecy, a property in which compromise of a long-term private key does not let an attacker decrypt previously captured sessions...
PKCS
Public-Key Cryptography Standards, a family of specifications covering common cryptographic formats and operations. It shows up in application security,...
PKI
PKI, or Public Key Infrastructure, is the framework of hardware, software, policies, and procedures that manages the creation, distribution, storage, and...
Post-Quantum
Describing cryptographic algorithms, migration efforts, or threat models designed to remain secure against attackers with large-scale quantum computers....
Post-Quantum Cryptography
Cryptographic algorithms designed to resist attacks from both classical and quantum computers. NIST standardized three post-quantum algorithms in 2024: ML-KEM...
Pre-Shared Key
A secret key known to all participating parties in advance and used for authentication or encryption, commonly in VPNs and WPA/WPA2-Personal wireless networks....
Private Key
A cryptographic concept related to private key, secure communication, key handling, or trust establishment. It shows up in application security, identity,...
Protocol Security
The security properties and protections of a communication protocol, including authentication, confidentiality, integrity, replay resistance, and downgrade...
Public Key
A cryptographic concept related to public key, secure communication, key handling, or trust establishment. It shows up in application security, identity,...
Public Key Cryptography
An encryption system using mathematically linked key pairs: a public key (shared openly) for encryption/verification and a private key (kept secret) for...
Public Key Infrastructure
A cryptographic concept related to public key infrastructure, secure communication, key handling, or trust establishment. It shows up in application security,...
Registry Key
A cryptographic concept related to registry key, secure communication, key handling, or trust establishment. It shows up in application security, identity,...
Root Key
A top-level cryptographic key on which other keys, signatures, or trust relationships ultimately depend. Root keys are used in PKI, secure boot, HSM...
RSA
A public key cryptosystem used for encryption, signatures, and secure key exchange. It shows up in application security, identity, infrastructure, or incident...
Salt
A random value appended or prepended to a password before hashing, ensuring that identical passwords produce different hash outputs. Salts defeat precomputed...
Secure Random
A random number generator that draws from a cryptographically secure entropy source (such as `/dev/urandom` or the OS CSPRNG), producing output that is...
Security Key
A cryptographic concept related to security key, secure communication, key handling, or trust establishment. It shows up in application security, identity,...
Security Token
An identity or access control concept centered on security token and how systems verify or authorize actions. It shows up in application security, identity,...
Self-Signed Certificate
A cryptographic concept related to self-signed certificate, secure communication, key handling, or trust establishment. It shows up in application security,...
Session Token
An identity or access control concept centered on session token and how systems verify or authorize actions. It shows up in application security, identity,...
SHA-256
A cryptographic concept related to sha-256, secure communication, key handling, or trust establishment. It shows up in application security, identity,...
S/MIME
Secure/Multipurpose Internet Mail Extensions, a standard for signing and encrypting email messages. It shows up in application security, identity,...
SSL Certificate
A cryptographic concept related to ssl certificate, secure communication, key handling, or trust establishment. It shows up in application security, identity,...
SSL Stripping
A cryptographic concept related to ssl stripping, secure communication, key handling, or trust establishment. It shows up in application security, identity,...
SSO Token
An identity or access control concept centered on sso token and how systems verify or authorize actions. It shows up in application security, identity,...
Steganography
The practice of concealing a message, file, or data within another non-secret file or medium — such as hiding text inside an image's pixel data — so that the...
Stream Cipher
A symmetric cipher that encrypts data one bit or byte at a time using a keystream. It shows up in application security, identity, infrastructure, or incident...
Symmetric Encryption
A cryptographic concept related to symmetric encryption, secure communication, key handling, or trust establishment. It shows up in application security,...
TLS Certificate
A cryptographic concept related to tls certificate, secure communication, key handling, or trust establishment. It shows up in application security, identity,...
TLS Fingerprinting
A cryptographic concept related to tls fingerprinting, secure communication, key handling, or trust establishment. It shows up in application security,...
TLS Termination
A cryptographic concept related to tls termination, secure communication, key handling, or trust establishment. It shows up in application security, identity,...
Token Binding
An identity or access control concept centered on token binding and how systems verify or authorize actions. It shows up in application security, identity,...
Tokenization
An identity or access control concept centered on tokenization and how systems verify or authorize actions. It shows up in application security, identity,...
Web Crypto API
A browser-native JavaScript API (window.crypto.subtle) that exposes cryptographic primitives — hashing (SHA-256/384/512), HMAC, symmetric encryption...
Wildcard Certificate
A cryptographic concept related to wildcard certificate, secure communication, key handling, or trust establishment. It shows up in application security,...
zero-knowledge proof
A cryptographic method that allows one party (the prover) to convince another party (the verifier) that a statement is true without revealing any information...

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