Callback implementation for Cloak.Cipher. Determines whether this module can decrypt the given ciphertext.

Callback implementation for Cloak.Cipher. Decrypts a value encrypted with AES in GCM mode.

Callback implementation for Cloak.Cipher. Encrypts a value using AES in GCM mode.

Generates a random IV for every encryption, and prepends the key tag, IV, and ciphertag to the beginning of the ciphertext. The format can be diagrammed like this:

+----------------------------------------------------------+----------------------+
|                          HEADER                          |         BODY         |
+-------------------+---------------+----------------------+----------------------+
| Key Tag (n bytes) | IV (n bytes)  | Ciphertag (16 bytes) | Ciphertext (n bytes) |
+-------------------+---------------+----------------------+----------------------+
|                   |_________________________________
|                                                     |
+---------------+-----------------+-------------------+
| Type (1 byte) | Length (1 byte) | Key Tag (n bytes) |
+---------------+-----------------+-------------------+

The Key Tag component of the header breaks down into a Type, Length, and Value triplet for easy decoding.

Important: Because a random IV is used for every encryption, encrypt/2 will not produce the same ciphertext twice for the same value.