Implement Encyrpted Uplink Communication

[bsfisher]

Description

Encrypt uplink communication using aes-gcm256 crate. Will use sequential nonces as a message counter to prevent against replay attacks. The aes-gcm crate will handle byte validation.

Deliverables

• Messages inputted by operator returns encrypted bytes with a sequential nonce
• Aes-gcm key is stored in a secure location (placeholder can be used temporarily for development)
• Messages received via the comms handler parses the nonce and decrypts the bytes
• Comms handler does ignores messages using previous nonces
• Downlink is unchanged