Skein-512(384) Hash

What is Skein-512(384)?

Skein-512(384) is a truncated variant of the Skein cryptographic hash function, designed as part of the NIST SHA-3 competition in 2008 under the broader Skein family, which was intended to address perceived weaknesses in SHA-2 while maintaining compatibility with existing hash-based cryptographic standards. Structurally, Skein employs a modular design with three key components: a keyed-hash macro (KHM) that integrates a 256-bit subkey derived from the input message, a compression function organized into 16 parallel lanes of 64-bit words, and a variable-round counter (ranging from 72 to 96 rounds) to enhance security. The "512" suffix denotes the internal block size (512 bits per compression step), while "384" specifies the output length achieved via truncation of the final hash state, omitting the least significant 128 bits. Skein-512(384) was primarily proposed for applications requiring 384-bit security strength, such as digital signatures (e.g., ECDSA with 384-bit curves) or key derivation, where a shorter output than full 512-bit Skein was preferable without sacrificing collision resistance.

Despite its modular design, Skein-512(384) exhibits vulnerabilities rooted in its architectural choices and implementation trade-offs. The absence of a cryptographic salt in the keyed-hash macro renders it susceptible to length-extension attacks when used in keyed contexts, as adversaries can append arbitrary data to the input without invalidating the hash. Additionally, the parallel lane structure, while theoretically efficient, enables GPU/FPGA-based optimizations that exploit massive parallelism, reducing the effective computational cost of brute-force or collision-finding attacks. Studies have demonstrated that Skein’s round function—particularly the diffusion layer—lacks sufficient avalanche effect, allowing pattern-based attacks to propagate more predictably than in ideal hash functions. Finally, the truncated output (384 bits) reduces the effective security margin against preimage attacks, as modern quantum-resistant algorithms (e.g., SHA-3) achieve stronger security bounds with equivalent or larger outputs, while Skein’s fixed-round structure fails to adaptively adjust security parameters based on computational advancements.

Identifying Skein-512(384) 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 Skein-512(384), security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack Skein-512(384)

If you need to recover the plaintext password for a Skein-512(384) 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.