These classes are not directly related to the crypt functionality, but most were necessary for its implementation, so I see no reason not to make them available. You may find them useful for other purposes.
Base-16 binary-to-text encodings.
Base-2 binary-to-text encodings.
Base-32 binary to text encodings. I needed multiple variations of base-64 for the various crypt algorithms, and base-16 (hex) for test vectors, so base-32 is mostly a freebie. It's great for e-mail verifications, product keys - really anywhere you need someone to type in a randomly-generated code.
Base-64 binary-to-text encodings.
Performs generic binary-to-text encoding.
Performs low-level encryption and decryption using the Blowfish cipher.
Performs low-level encryption and decryption using the DES cipher.
Implements the PBKDF2 key derivation function.
Implements the Salsa20 hash function.
Implements the SCrypt key derivation function.
Provides comparison methods resistant to timing attack.
A callback to map arbitrary characters onto the characters that can be decoded.
Modifiers for Expensive Key Schedule (EKS) Blowfish key expansion behavior.