Asynchronous Side Channel Cipher Renegotiation
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Solution Overview
Problem
Established communication channels are vulnerable to attacks, particularly in peer-to-peer connections where asymmetric cryptography may not be available, necessitating a method to renegotiate ciphers used in encrypted tunnels without interrupting user experiences or requiring complex authentication processes.
Innovation Solution
Implementing an asynchronous side channel for renegotiating ciphers by transmitting a renegotiation request with a password and relative time offset, allowing devices to independently generate a new cipher and seamlessly transition from the old to the new cipher, while continuing to use the original cipher for a predetermined period to accommodate packet transmission differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single communication channel is maintained over a long period to reduce reconnection needs, then user experience is improved and reconnection complexity is reduced, but the channel becomes susceptible to attacks and cipher compromise
Solution Approach 1:
The system performs preliminary cipher renegotiation through a side channel before the main channel becomes vulnerable. By proactively establishing a new cipher through the side channel and maintaining both ciphers temporarily, the system prevents future security compromises rather than reacting after an attack occurs.
Solution Approach 2:
A side channel acts as an intermediary communication path for exchanging renegotiation requests and new ciphers. This separate channel allows security updates to be transmitted without disrupting the main communication channel, enabling secure cipher rotation while maintaining continuous service.
2Reliability
If cipher renegotiation is implemented to protect against attacks, then security is improved, but complex authentication processes and connection interruptions may occur
Solution Approach 1:
The renegotiation process is self-service in that both endpoints independently generate the same new cipher using a shared secret and counter value, without requiring complex mutual authentication protocols. Each device can autonomously compute the new cipher state, simplifying the authentication process while maintaining security.
Solution Approach 2:
The system changes parameters (counter value, salt) to generate new ciphers rather than requiring complete reauthentication. By modifying these parameters and regenerating keys through key derivation functions, the system achieves cipher rotation with simpler procedures compared to full authentication sequences.
3Reliability
If immediate cipher switching is performed to limit exposure time, then security is improved by limiting nefarious actor access, but packet loss and connection interruptions may occur
Solution Approach 1:
The system cushions against packet loss by maintaining both the old and new ciphers simultaneously for a transition period. This dual-cipher state acts as a buffer, allowing packets encrypted with either cipher to be successfully decrypted, preventing service interruption during the cipher transition window.
Solution Approach 2:
The cipher system is made dynamic by allowing both old and new ciphers to coexist temporarily. This dynamic state enables flexible packet handling where receivers can adapt to whichever cipher is used for incoming packets, ensuring continuous connectivity while transitioning to the new secure cipher.
4Ease of operation
If absolute time synchronization is used for cipher renegotiation, then coordination between devices is simplified, but clock mismatch complications arise and synchronization overhead increases
Solution Approach 1:
The system uses asymmetric time reference where one device (the initiator) establishes the time reference point and the other device relative to which time is measured. This asymmetric approach avoids the need for mutual clock synchronization, as only the relative time offset matters for coordinating the cipher change at both endpoints.
Solution Approach 2:
A relative time offset acts as an intermediary parameter that bridges the time reference between two devices with potentially mismatched clocks. Instead of requiring direct clock comparison, the system uses this offset value to coordinate the cipher change, eliminating synchronization overhead while maintaining coordination reliability.
Data Source
AI summary
A method for asynchronous side channel cipher renegotiation includes: establishing, by a first computing device, a first communication channel and a second communication channel with a second computing device, where the first communication channel is an encrypted tunnel and packages exchanged using the encrypted tunnel are encrypted using a first cipher; receiving, by a receiver of the first computing device, a renegotiation request from the second computing device using the second communication channel, where the renegotiation request includes at least a password value and a relative time; generating, by a processor of the first computing device, a second cipher using at least an encryption protocol and the password value; receiving, by the receiver of the first computing device, a new encrypted packet from the second computing device using the first communication channel; and decrypting, by the processor of the first computing device, the new encrypted packet using the second cipher.