Implemented AES256-GCM encryption of all network packets. Requires some more refactoring to remove redundant code and make it cleaner.

src/agents/monarch/core/task.nim

@@ -1,7 +1,7 @@
-import strutils, tables, json, strformat
+import strutils, tables, json, strformat, sugar
 
 import ../commands/commands
-import ../../../common/[types, serialize, utils]
+import ../../../common/[types, serialize, crypto, utils]
 
 proc handleTask*(config: AgentConfig, task: Task): TaskResult = 
 
@@ -20,40 +20,34 @@ proc handleTask*(config: AgentConfig, task: Task): TaskResult =
     # Handle task command
     return handlers[cast[CommandType](task.command)](config, task)
 
-proc deserializeTask*(bytes: seq[byte]): Task = 
+proc deserializeTask*(config: AgentConfig, bytes: seq[byte]): Task = 
 
     var unpacker = initUnpacker(bytes.toString)
 
-    let 
-        magic = unpacker.getUint32()
-        version = unpacker.getUint8()
-        packetType = unpacker.getUint8()
-        flags = unpacker.getUint16()
-        seqNr = unpacker.getUint32()
-        size = unpacker.getUint32()
-        hmacBytes  = unpacker.getBytes(16) 
-    
-    # Explicit conversion from seq[byte] to array[16, byte]
-    var hmac: array[16, byte]
-    copyMem(hmac.addr, hmacBytes[0].unsafeAddr, 16)
+    let header = unpacker.unpackHeader()
 
     # Packet Validation
-    if magic != MAGIC: 
+    if header.magic != MAGIC: 
         raise newException(CatchableError, "Invalid magic bytes.")
 
-    if packetType != cast[uint8](MSG_TASK): 
+    if header.packetType != cast[uint8](MSG_TASK): 
         raise newException(CatchableError, "Invalid packet type.")
 
     # TODO: Validate sequence number 
 
-    # TODO: Validate HMAC
+    # Decrypt payload 
+    let payload = unpacker.getBytes(int(header.size))
 
-    # TODO: Decrypt payload 
-    # let payload = unpacker.getBytes(size)
+    let (decData, gmac) = decrypt(config.sessionKey, header.iv, payload, header.seqNr)
+
+    if gmac != header.gmac:
+        raise newException(CatchableError, "Invalid authentication tag (GMAC) for task.")
+
+    # Deserialize decrypted data
+    unpacker = initUnpacker(decData.toString)
 
     let 
         taskId = unpacker.getUint32()
-        agentId = unpacker.getUint32()
         listenerId = unpacker.getUint32()
         timestamp = unpacker.getUint32()
         command = unpacker.getUint16()
@@ -68,17 +62,8 @@ proc deserializeTask*(bytes: seq[byte]): Task =
         inc i
 
     return Task(
-        header: Header(
-            magic: magic,
-            version: version,
-            packetType: packetType, 
-            flags: flags,
-            seqNr: seqNr,
-            size: size,
-            hmac: hmac 
-        ),
+        header: header,
         taskId: taskId,
-        agentId: agentId,
         listenerId: listenerId, 
         timestamp: timestamp,
         command: command,
@@ -86,7 +71,7 @@ proc deserializeTask*(bytes: seq[byte]): Task =
         args: args
     )
 
-proc deserializePacket*(packet: string): seq[Task] = 
+proc deserializePacket*(config: AgentConfig, packet: string): seq[Task] = 
 
     result = newSeq[Task]()
 
@@ -104,6 +89,6 @@ proc deserializePacket*(packet: string): seq[Task] =
             taskLength = unpacker.getUint32() 
             taskBytes = unpacker.getBytes(int(taskLength))
 
-        result.add(deserializeTask(taskBytes))
+        result.add(config.deserializeTask(taskBytes))
         
         dec taskCount