Can You Decrypt a Bcrypt Hash? No, and Here Is What Works Instead
Every week someone asks how to "decrypt" a bcrypt hash. Here is the short answer, and what to do instead. Originally published on BcryptGenerator.org . No, a bcrypt hash can't be decrypted. Not online, not with the salt, and not with a key, because there is no key. Bcrypt is a one-way hash: it turns a password into a fixed string, and there's no operation that turns that string back. The only way…
Decryption of bcrypt hashes is not possible. Bcrypt is a one-way hash function that converts passwords into fixed-length strings, with no possible operation to revert the process. The only way to find the original password from a bcrypt hash is through brute-force guessing, which is intentionally slow due to bcrypt's design.
The confusion often arises because people interpret "bcrypt decrypt" as a desire to recover the original password, but hashing and encryption are fundamentally different concepts. Encryption allows data to be read back if the proper key is available, while hashing is irreversible without attempting all possible combinations.
Bcrypt specifically serves the purpose of securely storing passwords without the need to retrieve them later. Its design makes it resistant to offline password cracking using precomputed tables. Therefore, storing passwords as bcrypt hashes is the recommended approach, as it ensures that even if the hash database is compromised, the actual passwords remain protected.
To verify if a password matches a bcrypt hash, you don't need to decrypt anything. You simply hash the candidate password using the same salt and cost factor as the stored hash, then compare the resulting hash to the stored hash. This process can be performed using the built-in password verification functions in various programming languages, such as `password_verify()` in PHP or `bcrypt.compare()` in Node.js.
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