CODEWITHSUNDEEP
javacryptographypasswordsbcryptsalt-cryptography
RodeoClown
RodeoClown

Reputation: 13788

Do I need to store the salt with bcrypt?

bCrypt's javadoc has this code for how to encrypt a password:

String pw_hash = BCrypt.hashpw(plain_password, BCrypt.gensalt());

To check whether a plaintext password matches one that has been hashed previously, use the checkpw method:

if (BCrypt.checkpw(candidate_password, stored_hash))
    System.out.println("It matches");
else
    System.out.println("It does not match");

These code snippets imply to me that the randomly generated salt is thrown away. Is this the case, or is this just a misleading code snippet?

Upvotes: 210

Views: 44049

Answers (1)

Greg Hewgill
Greg Hewgill

Reputation: 992697

The salt is incorporated into the hash (encoded in a base64-style format).

For example, in traditional Unix passwords the salt was stored as the first two characters of the password. The remaining characters represented the hash value. The checker function knows this, and pulls the hash apart to get the salt back out.

Upvotes: 240

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