AES Key Wrap (RFC 3394)
Encrypt a key under a key encryption key using the algorithm described in RFC 3394
| SecureVector!ubyte key | the plaintext key to encrypt | 
| SymmetricKey kek | the key encryption key | 
| AlgorithmFactory af | an algorithm factory | 
Decrypt a key under a key encryption key using the algorithm described in RFC 3394
| SecureVector!ubyte key | the encrypted key to decrypt | 
| SymmetricKey kek | the key encryption key | 
| AlgorithmFactory af | an algorithm factory |