Transparent serial encryption

摘要

Disclosed herein are methods and systems for configuring and using one or more block ciphering techniques in order to encrypt/decrypt serial data streams while maintaining cryptographic synchronization and attempting to minimize the amount of overhead introduced into the stream. The techniques disclosed herein may be used to encrypt and decrypt serial data streams using a block cipher in a manner that can be substantially transparent to the devices involved in the serial communication session. For example, the serial user data may be left unframed by the encryption device while monitoring for opportunistic times to transmit framed cryptographic synchronization information during periods of relative inactivity in an asynchronous serial data stream. A cryptographic device implementing the techniques described herein may be configured to implement one or more of an encryption device or a decryption device.

主权项

1. An encryption device comprising:
a first communication interface configured to receive a serial data stream; a processor configured to: generate a keystream using a block cipher operating in counter mode, wherein the keystream is generated based on at least a key value and a count value, encrypt the serial data stream using the keystream, detect an idle period in the serial data stream, insert a framed cryptographic synchronization message into the encrypted serial data stream at a position corresponding to the detected idle period, wherein the framed cryptographic synchronization message comprises an escape sequence and an indication of a count value to be used to generate keystream data; and a second communication interface configured to output the encrypted serial data and the framed cryptographic synchronization message.