Make an accelerated NRF52 implementation for AEX256-CTR crypto

src/nrf52/NRF52CryptoEngine.cpp

@@ -1,5 +1,69 @@
 
 #include "CryptoEngine.h"
+#include "configuration.h"
+#include "ocrypto_aes_ctr.h"
 
-// FIXME, do a NRF52 version
-CryptoEngine *crypto = new CryptoEngine();
+class NRF52CryptoEngine : public CryptoEngine
+{
+
+    /// How many bytes in our key
+    uint8_t keySize = 0;
+    const uint8_t *keyBytes;
+
+  public:
+    NRF52CryptoEngine() {}
+
+    ~NRF52CryptoEngine() {}
+
+    /**
+     * Set the key used for encrypt, decrypt.
+     *
+     * As a special case: If all bytes are zero, we assume _no encryption_ and send all data in cleartext.
+     *
+     * @param numBytes must be 16 (AES128), 32 (AES256) or 0 (no crypt)
+     * @param bytes a _static_ buffer that will remain valid for the life of this crypto instance (i.e. this class will cache the
+     * provided pointer)
+     */
+    virtual void setKey(size_t numBytes, uint8_t *bytes)
+    {
+        keySize = numBytes;
+        keyBytes = bytes;
+    }
+
+    /**
+     * Encrypt a packet
+     *
+     * @param bytes is updated in place
+     */
+    virtual void encrypt(uint32_t fromNode, uint64_t packetNum, size_t numBytes, uint8_t *bytes)
+    {
+        // DEBUG_MSG("NRF52 encrypt!\n");
+
+        if (keySize != 0) {
+            ocrypto_aes_ctr_ctx ctx;
+
+            initNonce(fromNode, packetNum);
+            ocrypto_aes_ctr_init(&ctx, keyBytes, keySize, nonce);
+
+            ocrypto_aes_ctr_encrypt(&ctx, bytes, bytes, numBytes);
+        }
+    }
+
+    virtual void decrypt(uint32_t fromNode, uint64_t packetNum, size_t numBytes, uint8_t *bytes)
+    {
+        // DEBUG_MSG("NRF52 decrypt!\n");
+
+        if (keySize != 0) {
+            ocrypto_aes_ctr_ctx ctx;
+
+            initNonce(fromNode, packetNum);
+            ocrypto_aes_ctr_init(&ctx, keyBytes, keySize, nonce);
+
+            ocrypto_aes_ctr_decrypt(&ctx, bytes, bytes, numBytes);
+        }
+    }
+
+  private:
+};
+
+CryptoEngine *crypto = new NRF52CryptoEngine();