Blake2 Hash

What is Blake2?

Blake2 is a modern cryptographic hash function designed by Jean-Philippe Aumasson in 2013 as an evolution of the original Blake hash (BLAKE), specifically optimized for performance while maintaining strong security properties. Structurally, Blake2 is a Merkle-Damgård iterated hash function with a variable output length (256–512 bits) and supports both a simple and a keyed variant (Blake2b and Blake2s, respectively). Its architecture leverages a 128-bit block size with a compression function that processes data through a series of permutation rounds, incorporating chaining variables, message schedule expansion, and modular arithmetic to resist common cryptanalytic attacks. Blake2 was explicitly engineered for real-world applications, prioritizing speed over theoretical security margins—achieving near-optimal performance on both CPUs and GPUs—while addressing some of the weaknesses in SHA-3 candidates by incorporating a more efficient compression scheme and configurable parameters for security/performance trade-offs. Its primary use-cases include password hashing (via variants like Blake2b with a salt), blockchain data integrity (e.g., Ethereum’s use in some implementations), and general-purpose hashing in performance-sensitive environments.

Blake2’s vulnerability to cracking stems from several architectural and implementation flaws, particularly its susceptibility to brute-force and collision attacks due to design trade-offs. Unlike SHA-3 winners like Keccak, Blake2 lacks a built-in salt mechanism in its core specification, making precomputed rainbow tables or dictionary attacks more feasible for password hashing unless mitigated externally. Its compression function, while faster than SHA-2, relies on a 128-bit internal state, which—though sufficient for most applications—can be exploited via GPU-accelerated hashing (e.g., using CUDA or OpenCL) to achieve high throughput for brute-force searches. Additionally, Blake2’s fixed-round structure (64 rounds for Blake2b) is theoretically secure but becomes impractical to defend against when combined with optimized hardware, as evidenced by attacks on weaker hash functions (e.g., MD5 or SHA-1). Collision resistance, while stronger than SHA-1, has been theoretically challenged in post-quantum scenarios, though no practical attacks exist yet. Finally, its lack of built-in key stretching in the basic variant makes it unsuitable for raw password storage without additional mechanisms like Argon2 or PBKDF2, exposing it to timing attacks or slow-down techniques if not properly integrated into security protocols.

Identifying Blake2 Hashes

Identifying a hash blindly is often difficult because multiple algorithms can output strings of the exact same length. For example, a standard 32-character hexadecimal string could be MD5, NTLM, MD4, or LM. To definitively identify Blake2, security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack Blake2

If you need to recover the plaintext password for a Blake2 hash during a penetration test or forensics investigation, you must supply the correct module ID to your cracking software. Use the exact commands provided at the top of this page to target the hash successfully.