cryptoBoxSeal :: Ptr CUCharBuffer that will hold the encrypted message of size (size of original message + cryptoBoxSealbytes) bytes
-> Ptr CUCharBuffer that holds the plaintext message
-> CULLongLength of the plaintext message
-> Ptr CUCharBuffer that holds public key of size cryptoBoxPublicKeyBytes bytes.
-> IO CIntReturns 0 on success and -1 on error.
cryptoBoxSeal creates a new key pair for each message and attaches the public
key to the ciphertext. The secret key is overwritten and is not accessible
after this function returns.
See: crypto_box_seal()