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

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

The cryptographic hash format `sha256(sha256($pass).$salt)` is a nested hashing scheme derived from the SHA-256 algorithm, a member of the SHA-2 family standardized by NIST (FIPS 180-4). Its structure involves two sequential SHA-256 operations: first, the plaintext password (`$pass`) is concatenated with a unique salt (`$salt`), then hashed; the resulting hash is concatenated back with the original salt (or a variant thereof), and the process is repeated. This double-hashing technique was historically employed to mitigate early cryptanalytic attacks by increasing computational overhead, though its primary use-case was in password storage systems where defense against brute-force and rainbow table attacks was critical. The inclusion of a salt (`$salt`)—a per-user random value—prevents precomputation attacks by ensuring identical passwords produce different hashed outputs, while the nested SHA-256 was intended to slow down offline cracking by doubling the number of hash operations per password guess. However, its design predates modern advancements in hardware acceleration (e.g., GPUs, FPGAs) and cryptographic best practices, rendering it obsolete for contemporary security requirements.

This format is vulnerable to cracking due to its susceptibility to **computational optimization attacks** and **reduced security margins**. The nested SHA-256 structure, while theoretically doubling the work factor, is easily parallelized across modern GPUs or FPGAs, which can evaluate millions of hashes per second via optimized libraries (e.g., Hashcat’s `sha256` kernel). The lack of a **key-stretching function** (e.g., Argon2, bcrypt, or PBKDF2) means the hashing process remains computationally linear, allowing attackers to leverage hardware acceleration to brute-force passwords at scale. Additionally, SHA-256’s **collision resistance** is not the primary concern here—rather, its **preimage resistance** is weakened by the absence of iterative hashing with adaptive work factors (e.g., variable rounds or memory-hard operations). Finally, the salt’s role is undermined if it is **short or predictable**, as modern tools can precompute or cache partial hashes (e.g., via rainbow tables for weak salts), rendering the double-hash redundant. The format’s reliance on brute-force deterrence alone makes it vulnerable to **distributed cracking networks**, where attackers coordinate resources to exploit its predictable computational cost.

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

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

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