sha1($salt.$pass) Hash

What is sha1($salt.$pass)?

The cryptographic hash format `sha1($salt.$pass)` originates from the SHA-1 (Secure Hash Algorithm 1) standard, a 160-bit (20-byte) hash function designed by the NSA and published as FIPS 180-1 in 1995, intended for digital signatures, message authentication, and password storage. The structure concatenates a unique salt (a random or entropy-derived value) with the plaintext password before hashing, producing a fixed-length hexadecimal digest (e.g., `5d41402abc4b2a76b9719d911017c592`). This format was widely adopted in early web authentication systems, particularly in PHP applications via `password_hash()` (pre-PHP 5.5) and legacy frameworks, due to its simplicity and compatibility with existing cryptographic toolkits. The primary use-case was secure password storage, where the salt mitigates rainbow table attacks by ensuring identical passwords produce unique hashes, though SHA-1’s design predates modern security standards and lacks key properties like collision resistance for contemporary applications.

The vulnerability of `sha1($salt.$pass)` stems from SHA-1’s inherent weaknesses, exacerbated by implementation flaws and hardware optimizations. SHA-1 suffers from known collision vulnerabilities (e.g., SHA-1 was broken in 2017 via Faster SHA-1), rendering it unsuitable for security-critical applications. The format’s reliance on a salt is ineffective against brute-force attacks when combined with GPU/ASIC acceleration (e.g., via tools like Hashcat), as modern password crackers leverage parallelized SHA-1 hashing pipelines to test millions of candidates per second. Additionally, the 160-bit output space is insufficient for modern entropy requirements, and the lack of key stretching (e.g., no iterative hashing or work factor) allows attackers to precompute hashes offline. The format’s obsolescence is further underscored by NIST’s deprecation of SHA-1 for security purposes in 2012, replaced by SHA-2 or SHA-3 families, which incorporate larger output sizes and resistance to quantum and classical collision attacks.

Identifying sha1($salt.$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 sha1($salt.$pass), security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack sha1($salt.$pass)

If you need to recover the plaintext password for a sha1($salt.$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.