Keccak256 Online

Use the following file select drop zone to generate the Keccak256 of a given file:

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Keccak256 - Keccak Hash Algorithm

Keccak256 is a cryptographic hash function that produces a 256-bit (32-byte) hash value. It is the original version of the Keccak algorithm that won the SHA-3 competition, and is widely used in blockchain applications, most notably as the hashing algorithm in Ethereum.

A cryptographic hash function is a mathematical function that takes input data and produces a fixed-size output (often called a hash or message digest) that is unique to the input data. The output is typically a sequence of numbers and letters that represents a digital fingerprint of the input data.

Keccak256 is used extensively in blockchain technology, particularly in Ethereum for:

• Address Generation: Ethereum addresses are derived by taking the Keccak256 hash of the public key and using the last 20 bytes.
• Transaction Hashing: Each transaction in Ethereum is hashed using Keccak256 to create a unique transaction identifier.
• Smart Contracts: Function selectors in Ethereum smart contracts are the first 4 bytes of the Keccak256 hash of the function signature.
• Merkle Trees: Keccak256 is used to construct Merkle trees in Ethereum, which are fundamental to the blockchain's data structure.
• Data Integrity: Like other hash functions, Keccak256 ensures data integrity and can be used for digital signatures and verification.

Keccak vs SHA3

It's important to note that Keccak256 is not the same as SHA3-256. When Keccak won the SHA-3 competition, NIST made small changes to the algorithm before standardizing it as SHA-3. Ethereum and many blockchain applications use the original Keccak algorithm (pre-NIST changes), which is why it's specifically called "Keccak256" rather than "SHA3-256".

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