A device for and method of authenticated encryption by concatenating a first user-datum with a second datum, concatenating the first datum with a third datum, encrypting the results, concatenating the encrypted results, concatenating the result with a message and a fifth user-definable datum, hashing the result, concatenating the result with the message, dividing the result into blocks, concatenating the first datum with a sixth datum, generating key-stream blocks from the result using a block cipher in counter mode, combining the blocks and key-stream blocks, concatenating the result with the first datum and the fifth datum, and transmitting the result to a recipient. The recipient extracts the hash value from the received ciphertext, generates a hash value from the first through fifth datums and plaintext derived from the ciphertext, and compares the two. If they match then the plaintext and fifth datum are as the sender intended.