sha1($pass.$salt) Hash

What is sha1($pass.$salt)?

SHA-1 was originally designed in 1995 by the NSA as part of the SHA (Secure Hash Algorithm) family to provide a 160-bit (20-byte) hash value for data integrity verification, digital signatures, and message authentication. The format `sha1($pass.$salt)` refers to a password hashing scheme where the plaintext password (`$pass`) is concatenated with a unique salt (`$salt`) before being hashed via SHA-1. Salting mitigates rainbow table attacks by ensuring each password hash is unique, even for identical inputs, though SHA-1 itself was never intended for cryptographic password storage. This method became prevalent in early web authentication systems (e.g., PHP’s `crypt()`-like implementations) due to its simplicity and compatibility with legacy systems, though it lacks the collision resistance and security guarantees of modern cryptographic primitives.

The vulnerability of `sha1($pass.$salt)` stems from SHA-1’s inherent weaknesses: its 160-bit output is now considered insecure due to practical collision attacks (e.g., SHA-1 has been broken for ~$2^69 operations), and its 512-bit block size enables GPU/ASIC optimizations via parallelized brute-force (e.g., hashcat’s `sha1($pass.$salt)` mode). Without proper iteration counts (e.g., PBKDF2-style hashing), attackers exploit GPU clusters to crack hashes in hours/days. Even with salting, weak salts (e.g., fixed-length or predictable) reduce security, and SHA-1’s deterministic nature allows precomputed tables for short passwords. Modern standards (e.g., Argon2, bcrypt) replace it due to these flaws, though legacy systems still risk exposure via dictionary attacks or hardware-accelerated cracking.

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

How to Crack sha1($pass.$salt)

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