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Cybersecurity

What is Hashing?

Quick answer

Transforming data of any size into a fixed-length string, called a hash, using a one-way mathematical function.

Hashing, explained

A hash function takes an input, such as a password or a file, and produces a fixed-size output that looks random. The same input always gives the same hash, but even a tiny change produces a completely different result, and it should be practically impossible to reverse the process.

Hashing has many uses. Websites store password hashes instead of actual passwords, ideally with slow, salted algorithms such as bcrypt or Argon2. File downloads publish a hash so you can verify nothing was altered. Blockchains link blocks using hashes of previous blocks. Common algorithms include SHA-256; older ones like MD5 and SHA-1 are considered broken for security purposes. Hashing differs from encryption, which is designed to be reversible with a key.

Related terms

Blockchain

A shared, append-only digital ledger in which records are grouped into blocks that are cryptographically linked in sequence.

Brute Force Attack

An attempt to break into an account or decrypt data by systematically trying many possible passwords or keys until one works.

Encryption

The process of converting readable data into scrambled ciphertext that only someone with the correct key can decode.

Proof of Work

A blockchain consensus mechanism in which miners compete to solve computational puzzles to add new blocks and secure the network.

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