BCrypt.checkpw() Invalid salt version exception

jBcrypt is too old and actually unmaintained. Please consider switching to a new implementation of that library to handle the new $2y$ versions.

I solved this using this pure Java library https://github.com/patrickfav/bcrypt, adding it in my current Scala project.

With the following function I can finally verify the hashes created with VERSION_2Y:

  /**
    * Verifies an encrypted password against the expected value
    *
    * @link https://github.com/patrickfav/bcrypt
    * @param hash The hashed password (encypted with BCrypt version $2Y$)
    * @param password The unencrypted password string
    */
  private def verifyBcryptHash(hash: String, password: String): Boolean = {
    if (hash == null || hash.trim.isEmpty)
      false
    else
      BCrypt
        .verifyer()
        .verifyStrict(
          password.toCharArray(),
          hash.toCharArray(),
          BCrypt.Version.VERSION_2Y
        )
        .verified
  }

I'm very sorry for bothering with this question. I had just one bug in the code that was saving plain string to the DB instead of the BCrypted one. It was whole called from some other part of code.

For others encountering the same exception, check that you have the BCrypt.checkpw parameters the right way round. (I didn't and therefore found this question before I realised my silly mistake.)

Or as the OP answered himself, log/debug the value of the hashed password to double check you are actually comparing a hashed password! It should be a 60-char string in the format $2a$10$llw0G6IyibUob8h5XRt9xuRczaGdCm/AiV6SSjf5v78XS824EGbh.

I encountered the same problem; Make sure your password is stored in the database in hashed format instead of plain text. Here is a Bcrypt generator to translate your plain text password into a Bcrypt hash.