Password Hash Generator & Verifier Password hash generation and verification tools

General Hash (such as MD5, SHA-256) is designed for data integrity verification and has extremely fast calculation speed. Password Hash (such as bcrypt, Argon2id) is specially designed for password storage and has the following characteristics:

• Deliberately slow: Control the calculation time through Cost Factor and increase the cost of brute force cracking
• Automatically add Salt: Use a different Salt for each password to prevent rainbow table attacks
• GPU/ASIC resistant: Argon2id requires a lot of memory, making parallel acceleration difficult for GPUs

Conclusion:Never use MD5 or SHA-256 to store passwords directly, please use bcrypt, Argon2id, or PBKDF2.

Salt (salt value) is a piece of random data that is spliced with the password before calculating the hash. Its functions include:

• Anti-rainbow watch: Pre-calculated Hash comparison table (rainbow table) cannot be used because each Salt is different
• Anti-duplication: Even if two users set the same password, the hash generated will be different.
• Increase cracking costs: The attacker needs to perform brute force cracking on each Salt separately, which cannot be processed in batches.

The standard practice is to use a different random Salt for each password (at least 16 bytes) and store the Salt together with the Hash (the output of bcrypt already contains the Salt).

• Argon2id(Most Recommended): Winner of the 2015 cryptographic hashing competition, the most advanced design, resistant to both GPUs and ASICs. Memory and iteration parameters need to be adjusted.

• bcrypt(Large recommendation base): Designed in 1999, mature and stable, widely supported. Built-in Salt and Cost controls are the default choice for many frameworks.

• PBKDF2(Available): FIPS certified standard, strength controlled by number of iterations. Weak to GPU/ASIC, requires extremely high number of iterations (hundreds of thousands).

• SHA-256(Educational use only): Not recommended for password storage, no Salt, too fast, and easily vulnerable to GPU brute force cracking.

Suggestions:New projects use Argon2id and existing projects maintain bcrypt, both of which are far superior to PBKDF2.

Cost Factor controls the computational difficulty of cryptographic hashes. Taking bcrypt as an example, a Cost of 10 means 2¹⁰ = 1024 iterations. Each additional cost of 1 approximately doubles the calculation time.

• Cost 8 — Faster, affordable for low-end hardware (~50ms)
• Cost 10 - generally recommended value, balancing security and performance (about 200ms)
• Cost 12 — Safer, suitable for scenarios with high security requirements (about 800ms)
• Cost 14 — Very safe, but user experience may be affected (about 3s)

It is recommended to adjust the Cost according to the server performance to maintain each verification time at 200-500ms. As hardware advances, the Cost value should be gradually increased.

The main problems with storing passwords directly in SHA-256 (or MD5):

• too fast: GPU can calculate SHA-256 billions of times per second, brute force cracking is only a matter of time
• No Salt: The same password generates the same hash, and the rainbow table attack is effective
• Zero GPU-resistant design: No memory required, GPU can perform massive parallel computing

Even with Salt and multiple iterations (as PBKDF2 does), the underlying design of SHA-256 is still less suitable as a cryptographic hash algorithm than bcrypt or Argon2id.

The simplest way to remember:Hash is used for files, Password Hash is used for passwords.

No. Password hashing is a one-way function, and by design it is impossible to reverse the original password from the hash. This is why password hashes are suitable for storing passwords - even if the database is leaked, the attacker cannot directly obtain the clear text passwords.

When verifying a password, the system recalculates the hash of the password entered by the user, and then compares it with the hash stored in the database to see if it is the same. This is how the "verify" feature of this tool works.

Any service claiming to be able to "decrypt" or "restore" password hashes is a scam.- They just use rainbow tables or dictionaries of common passwords for comparison.