Hash
Definition
A fixed-length string of characters generated from input data by a hash function, used for data integrity verification, password storage, and digital signatures.
A hash function takes input data of any size and produces a fixed-length output string called a hash, digest, or checksum. Good hash functions are deterministic (same input always produces same output), fast to compute, irreversible (cannot reconstruct input from hash), and collision-resistant (different inputs produce different hashes).
Common hash algorithms include SHA-256 (used in Bitcoin and digital certificates), SHA-3, bcrypt and Argon2 (designed for password hashing with built-in salting and adjustable work factors), and MD5 (now considered insecure but still used for checksums).
Hashing has numerous applications: verifying file integrity (checksums), storing passwords securely (never store plaintext passwords), data structures (hash tables), digital signatures, blockchain technology, and de-duplication. Unlike encryption, hashing is a one-way process and cannot be reversed to recover the original data.
Related Calculators
Related Terms
Encryption
techThe process of converting readable data (plaintext) into an unreadable format (ciphertext) using an algorithm and key, protecting it from unauthorized access.
SSL/TLS (Secure Sockets Layer / Transport Layer Security)
techCryptographic protocols that provide secure communication over computer networks, encrypting data between a web server and browser.
Base64
techA binary-to-text encoding scheme that converts binary data into a string of ASCII characters, commonly used for embedding data in web pages and emails.
JWT (JSON Web Token)
techA compact, URL-safe token format used for securely transmitting information between parties as a JSON object, commonly used for authentication.
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