Unmanned Aerial Vehicles (UAVs) are autonomous aircraft systems widely used in public, civilian, and military applications for surveillance and monitoring. However, their limited memory and battery capacity constrain their ability to perform long-term, reliable missions in complex environments. To overcome this, multiple UAVs can collaborate by sharing and merging data. Ensuring secure communication among these UAVs is crucial, particularly for maintaining data confidentiality and authentication, which, if compromised, can lead to catastrophic outcomes. Although several cryptographic and non-cryptographic approaches have been proposed for UAV security, most focus on UAV-to-Ground Control Station (GCS) communication. UAV-to-UAV communication remains a vulnerable and underexplored area. Existing solutions like the Value-to-HMAC approach introduce significant overhead due to the use of predefined hash tables for message verification. This study presents a lightweight security framework that provides confidentiality and authentication for UAV-to-UAV and UAV-to-GCS communication. This approach integrates HMAC with AES-128 encryption using the “encrypt-then-MAC” technique, suitable for resource-constrained UAVs. The experimental evaluations demonstrate that the proposed method offers improved performance, reduced computational overhead, and robust security compared to existing solutions, achieving data integrity, authentication, and confidentiality.