sha256($salt.sha256($pass)) Hash

What is sha256($salt.sha256($pass))?

The cryptographic hash format `sha256($salt.sha256($pass))` is a two-stage hashing scheme derived from the SHA-2 family of cryptographic hash functions, specifically SHA-256, which was standardized in 2001 as part of NIST’s FIPS 180-4. This construction, often referred to as a *double-hash* or *salted hash*, was popularized in the early 2010s as a defense against rainbow table attacks and brute-force cracking. The structure involves concatenating a cryptographic salt (a unique, randomly generated value per password) with the initial SHA-256 hash of the plaintext password (`$pass`), followed by another SHA-256 hashing operation. This process effectively increases the computational overhead while preserving the collision resistance properties of SHA-256. The primary use-case lies in password storage systems where security against precomputed attacks and offline cracking is critical, though its adoption declined with the rise of more modern key derivation functions like bcrypt, Argon2, or PBKDF2, which incorporate additional computational delays and adaptive work factors.

Despite its apparent robustness, this scheme is vulnerable to cracking due to several architectural limitations. The primary weakness stems from its reliance on SHA-256’s fixed output size (256 bits) and lack of built-in slowdown mechanisms, making it susceptible to GPU/ASIC acceleration via optimized implementations like CUDA or OpenCL. Additionally, while salting mitigates rainbow table attacks, the double-hash structure does not inherently resist *preimage attacks* or *length-extension attacks* when improperly implemented, as the salted input (`$salt.sha256($pass)`) remains vulnerable to brute-force exhaustion if the password space is small. Furthermore, the absence of a *work factor*—a tunable parameter to adjust computational difficulty—means attackers can deploy parallelized cracking tools (e.g., Hashcat) to test millions of hashes per second, rendering the scheme impractical for modern security standards where passwords may be stored indefinitely.

Identifying sha256($salt.sha256($pass)) 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 sha256($salt.sha256($pass)), security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack sha256($salt.sha256($pass))

If you need to recover the plaintext password for a sha256($salt.sha256($pass)) 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.