Challenge implementation

src_features/getChallenge/challenge.h

@@ -0,0 +1,14 @@
+#ifdef HAVE_DOMAIN_NAME
+
+#ifndef CHALLENGE_H_
+#define CHALLENGE_H_
+
+#include <stdint.h>
+
+void roll_challenge(void);
+uint32_t get_challenge(void);
+void handle_get_challenge(void);
+
+#endif  // CHALLENGE_H_
+
+#endif  // HAVE_DOMAIN_NAME

src_features/getChallenge/cmd_get_challenge.c

@@ -0,0 +1,38 @@
+#ifdef HAVE_DOMAIN_NAME
+
+#include <os.h>
+#include <os_io.h>
+#include <cx.h>
+#include "apdu_constants.h"
+#include "challenge.h"
+
+static uint32_t challenge;
+
+/**
+ * Generate a new challenge from the Random Number Generator
+ */
+void roll_challenge(void) {
+    challenge = cx_rng_u32();
+}
+
+/**
+ * Get the current challenge
+ *
+ * @return challenge
+ */
+uint32_t get_challenge(void) {
+    return challenge;
+}
+
+/**
+ * Send back the current challenge
+ */
+void handle_get_challenge(void) {
+    PRINTF("New challenge -> %u\n", get_challenge());
+    U4BE_ENCODE(G_io_apdu_buffer, 0, get_challenge());
+    U2BE_ENCODE(G_io_apdu_buffer, 4, APDU_RESPONSE_OK);
+
+    io_exchange(CHANNEL_APDU | IO_RETURN_AFTER_TX, 6);
+}
+
+#endif  // HAVE_DOMAIN_NAME