## Overview Blake2 is a cryptographic [[hash function]] that is faster at hashing than [[MD5]], [[SHA-1]], and [[SHA-2]], while retaining a high-security level. It is often viewed as a successor to the Blake [[algorithm]] and comes in two main flavors: [[BLAKE2b]] (optimized for 64-bit platforms) and BLAKE2s (optimized for 8- to 32-bit platforms). ## Key Characteristics - **Performance**: Known for its exceptional speed, particularly in software implementations. - **Security**: Designed as an alternative to [[MD5]] and [[SHA-1]]/2 without sacrificing security. As of the latest update, no practical vulnerabilities have been found. - **Flexibility**: Supports keying (making it a MAC), personalization, and salting, and can return digests of any size between 1 and 64 bytes (BLAKE2b) or 1 and 32 bytes (BLAKE2s). - **Lightweight**: Especially in its BLAKE2s form, it's well-suited for environments with constrained resources. ## Common Uses - **Cryptographic Systems**: Due to its speed and security profile, it finds its place in various cryptographic protocols and systems. - **Checksums**: Used for verifying the integrity of data. - **Password Hashing**: While not its most common use, it can be employed for hashing passwords, particularly when speed is desired. ## Design - **Base**: The design is based on the cryptographic primitive ChaCha, a stream cipher developed by Daniel J. Bernstein. - **Sponge Construction**: Unlike [[SHA-2]], which is based on the [[Merkle–Damgård construction]], BLAKE2 uses the [[HAIFA construction]], which avoids length extension attacks without needing to resort to the [[HMAC construction]]. ## Notable Implementations - **libsodium**: A software library for encryption, decryption, signatures, password hashing, and more, has adopted BLAKE2 as one of its preferred hashing algorithms. - **Argon2**: The winner of the Password Hashing Competition (and recommended for password hashing) uses BLAKE2 internally. ## Related Concepts - **Blake**: The predecessor to Blake2. - **[[Cryptographic Hash Function]]**: A method for ensuring data integrity by producing a fixed-size output from variable-size input. - **[[SHA-3]]**: Another successor to [[SHA-2]] but was developed separately from BLAKE2.