Question: In a 3GPP network, when a Data Radio Bearer (DRB) undergoes a type change from Master eNodeB (MeNB) terminated to Secondary gNodeB (SgNB) terminated and back to MeNB terminated, what security concern must the MeNB mitigate through an implemented mechanism?
Option 1: Increased latency due to handover
Option 2: Reduced throughput from bearer reconfiguration
Option 3: Compromised Quality of Service (QoS) for concurrent bearers
Option 4: Key stream reuse, potentially compromising encryption security
Explanation: The scenario described poses a risk of key stream reuse, which could severely compromise the security of encrypted data transmissions. By changing the termination point of a DRB and then reverting it, there's a possibility that the same key stream (used for encrypting data) might be reused, undermining the confidentiality and integrity of the data. The MeNB must implement a mechanism to prevent this specific security vulnerability, ensuring the continued secure transmission of data.