Cipher Key Handover Sequence Gap Resolution
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Solution Overview
Problem
In wireless communications, particularly in 4G and 5G systems, key confusion during cell handover leads to data transmission interruptions due to the need for key updates, where the receiving party is unsure when a new key starts being used, causing issues with deciphering data packets.
Innovation Solution
A method where the sending party sets a sequence number discontinuity, or 'hole,' between data packets encrypted with old and new keys, and sends indication information to the receiving party to skip these intermediate packets, allowing seamless decryption using the correct keys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a key update is performed during cell handover, then security protection is improved, but data transmission interruption occurs
Solution Approach 1:
The patent applies preliminary action by pre-configuring the receiving party with the new key before the actual key update occurs during handover. The sending party includes the new key in the handover command message, allowing the receiving party to prepare for key switching in advance. This ensures that when the key update becomes necessary, both parties are already synchronized, preventing data transmission interruption while maintaining security protection.
2Measurement precision
If the receiving party uses a new key immediately after handover, then deciphering accuracy is improved, but key confusion occurs during the transition period
Solution Approach 1:
The patent uses an intermediary approach by introducing a key update indication message that carries the new key from the sending party to the receiving party before the actual handover completes. This intermediary message ensures that the receiving party has the correct new key information before it needs to use it, eliminating key confusion during the transition period while maintaining high deciphering accuracy.
3Stability of the object's composition
If the sequence numbers are kept continuous during key update, then data packet ordering is maintained, but the receiving party cannot determine which key to use for deciphering
Solution Approach 1:
The patent applies preliminary action by providing the new key to the receiving party in advance through the handover command message, before the key actually becomes active. This allows the receiving party to have the new key information ready and associated with the appropriate sequence numbers beforehand, making it easy to determine which key to use for deciphering each data packet while maintaining continuous sequence numbering.
Data Source
AI summary
This application discloses a communications method. The method may include: receiving, by a receiving party, indication information sent by a first device, where the indication information is used to indicate at least one intermediate sequence number; receiving a data packet of the bearer sent by the first device; and skipping the at least one intermediate sequence number based on the indication information, deciphering, by using the old key, a data packet that is located on the bearer and whose sequence number is followed by the at least one intermediate sequence number, and deciphering, by using the new key, a data packet that is located on the bearer and whose sequence number follows the at least one intermediate sequence number.