Tactical Satellites (TacSats) are designed for command, control and communications among troops in the battlefield. TacSat Network has a large number of satellite terminals. These terminals are stationary and mobile terminals. Key management for TacSats is milestone because terminals in battlefield need to communicate but these terminals cannot communicate unless they share a secret key. In this paper, we proposed three novel mechanisms; the usage of key management unit (KMU) for authentication of satellite terminal operator, the implementation of certificates shared verification key management for satellite terminals, and new Group Key Management (GKM) algorithm. This new algorithm established group key between satellite terminals for TacSat with high speed keys distribution, high performance, low setup time and protecting the satellite terminal from theft. Key management for TacSat needs certificates verification for satellite terminals where previous work assumed long time for certificates verification.