US Patent 8713311 Encryption using alternate authentication key

Methods for changing authentication keys when transmitting data are provided. In one aspect, a method includes receiving a first data packet including a first sender-generated authentication value generated using a first authentication key, and a first message encrypted using a first encryption key, and receiving an indication that subsequent packets will include authentication values generated using a second authentication key. The method also includes receiving a second packet includes a second sender-generated authentication value and an encrypted second message, and applying the second authentication key to the second packet to generate a recipient-generated authentication value. The encrypted second message is decrypted if these two authentication values match. Otherwise, the first authentication key is applied to the second packet to generate another recipient-generated authentication value. If these two authentication values match, the encrypted message is decrypted using the first encryption key. Systems and machine-readable media are also provided.