SHAKE128

SHAKE128 is a member of the SHA-3 family of cryptographic hash functions, standardized by NIST. Unlike fixed-output hash functions like SHA-256 or SHA-3-256, SHAKE128 is a customizable-output hash function (COH), meaning the length of its output digest can be arbitrarily chosen by the user. The "128" in its name refers to the security level it provides, approximately equivalent to 128 bits of security against collision attacks.

SHAKE128 is based on the Keccak algorithm, which was the winner of the NIST SHA-3 competition. Keccak uses a sponge construction, where data is "absorbed" into an internal state and then "squeezed" out as the hash output. This construction allows for flexible output lengths. SHAKE128 processes input data in blocks and applies a series of permutations to its internal state.

The primary advantage of SHAKE128 is its flexibility. This makes it suitable for a wide range of cryptographic applications where a variable-length hash is needed. Examples include key derivation functions (KDFs), message authentication codes (MACs), and pseudo-random number generators (PRNGs). Its computational efficiency and strong security properties make it a practical choice for modern cryptography. While SHAKE256 offers a higher security level, SHAKE128 is often sufficient for many common use cases and provides faster performance.