Put a bit of order in the src directory, group and name things appropriately

src/platform/rp2040/rp2040CryptoEngine.cpp

@@ -0,0 +1,36 @@
+#include "configuration.h"
+#include "CryptoEngine.h"
+#include "aes.hpp"
+
+class RP2040CryptoEngine : public CryptoEngine
+{
+  public:
+    RP2040CryptoEngine() {}
+
+    ~RP2040CryptoEngine() {}
+
+    /**
+     * Encrypt a packet
+     *
+     * @param bytes is updated in place
+     */
+    virtual void encrypt(uint32_t fromNode, uint64_t packetNum, size_t numBytes, uint8_t *bytes) override
+    {
+        if (key.length > 0) {
+            AES_ctx ctx;
+            initNonce(fromNode, packetNum);
+            AES_init_ctx_iv(&ctx, key.bytes, nonce);
+            AES_CTR_xcrypt_buffer(&ctx, bytes, numBytes);
+        }
+    }
+
+    virtual void decrypt(uint32_t fromNode, uint64_t packetNum, size_t numBytes, uint8_t *bytes) override
+    {
+        // For CTR, the implementation is the same
+        encrypt(fromNode, packetNum, numBytes, bytes);
+    }
+
+  private:
+};
+
+CryptoEngine *crypto = new RP2040CryptoEngine();