From 58ced259786b76882ab9f208f2041ed5f890366f Mon Sep 17 00:00:00 2001
From: Robert Quattlebaum <darco@deepdarc.com>
Date: Fri, 5 Jan 2018 22:20:38 -0800
Subject: [PATCH] mifare-ultralight: Added mifare_ultralightc_set_key()

This new method sets the authentication key on a MIFARE Ultralight C
card, and is analogous to `ntag21x_set_key()`.
---
 libfreefare/freefare.h          |  1 +
 libfreefare/mifare_ultralight.c | 52 +++++++++++++++++++++++++++++++++
 test/test_mifare_ultralight.c   | 48 ++++++++++++++++++++++++++++++
 3 files changed, 101 insertions(+)

diff --git a/libfreefare/freefare.h b/libfreefare/freefare.h
index d84ed08..85b1668 100644
--- a/libfreefare/freefare.h
+++ b/libfreefare/freefare.h
@@ -85,6 +85,7 @@ int		 mifare_ultralight_read(FreefareTag tag, const MifareUltralightPageNumber p
 int		 mifare_ultralight_write(FreefareTag tag, const MifareUltralightPageNumber page, const MifareUltralightPage data);
 
 int		 mifare_ultralightc_authenticate(FreefareTag tag, const MifareDESFireKey key);
+int		 mifare_ultralightc_set_key(FreefareTag tag, MifareDESFireKey key);
 bool		 is_mifare_ultralight(FreefareTag tag);
 bool		 is_mifare_ultralightc(FreefareTag tag);
 bool		 is_mifare_ultralightc_on_reader(nfc_device *device, nfc_iso14443a_info nai);
diff --git a/libfreefare/mifare_ultralight.c b/libfreefare/mifare_ultralight.c
index 5562fb0..f85b478 100644
--- a/libfreefare/mifare_ultralight.c
+++ b/libfreefare/mifare_ultralight.c
@@ -332,6 +332,58 @@ mifare_ultralightc_authenticate(FreefareTag tag, const MifareDESFireKey key)
     return 0;
 }
 
+/*
+ * Set the authentication key for the provided MIFARE tag.
+ */
+int
+mifare_ultralightc_set_key(FreefareTag tag, MifareDESFireKey key)
+{
+    MifareUltralightPage data;
+
+    if (key->type != T_3DES) {
+	errno = EINVAL;
+	return -1;
+    }
+
+    data[0] = key->data[7];
+    data[1] = key->data[6];
+    data[2] = key->data[5];
+    data[3] = key->data[4];
+
+    if (mifare_ultralight_write(tag, 0x2C, data)<0) {
+	return -1;
+    }
+
+    data[0] = key->data[3];
+    data[1] = key->data[2];
+    data[2] = key->data[1];
+    data[3] = key->data[0];
+
+    if (mifare_ultralight_write(tag, 0x2D, data)<0) {
+	return -1;
+    }
+
+    data[0] = key->data[15];
+    data[1] = key->data[14];
+    data[2] = key->data[13];
+    data[3] = key->data[12];
+
+    if (mifare_ultralight_write(tag, 0x2E, data)<0) {
+	return -1;
+    }
+
+    data[0] = key->data[11];
+    data[1] = key->data[10];
+    data[2] = key->data[9];
+    data[3] = key->data[8];
+
+    if (mifare_ultralight_write(tag, 0x2F, data)<0) {
+	return -1;
+    }
+
+    return 0;
+}
+
 bool
 is_mifare_ultralight(FreefareTag tag)
 {
diff --git a/test/test_mifare_ultralight.c b/test/test_mifare_ultralight.c
index fdea38b..3fde28e 100644
--- a/test/test_mifare_ultralight.c
+++ b/test/test_mifare_ultralight.c
@@ -176,3 +176,51 @@ test_mifare_ultralightc_authenticate(void)
 	cut_omit("mifare_ultralightc_authenticate() skipped on Ultralight");
     }
 }
+
+void
+test_mifare_ultralightc_set_key(void)
+{
+    int res;
+    const uint8_t default_key_data[16] = { 0x49, 0x45, 0x4D, 0x4B, 0x41, 0x45, 0x52, 0x42, 0x21, 0x4E, 0x41, 0x43, 0x55, 0x4F, 0x59, 0x46 };
+    const uint8_t test_key_data[16] = { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0XEE, 0xFF };
+    MifareDESFireKey default_key;
+    MifareDESFireKey test_key;
+
+    if (is_mifare_ultralightc(tag)) {
+	default_key = mifare_desfire_3des_key_new(default_key_data);
+	test_key = mifare_desfire_3des_key_new(test_key_data);
+
+	// Change the key to the new key
+	res = mifare_ultralightc_set_key(tag, test_key);
+	cut_assert_equal_int(0, res, cut_message("mifare_ultralightc_set_key() failed"));
+
+	res = mifare_ultralight_disconnect(tag);
+	cut_assert_equal_int(0, res, cut_message("mifare_ultralight_disconnect() failed"));
+
+	res = mifare_ultralight_connect(tag);
+	cut_assert_equal_int(0, res, cut_message("mifare_ultralight_connect() failed"));
+
+	// Test the new key
+	res = mifare_ultralightc_authenticate(tag, test_key);
+	cut_assert_equal_int(0, res, cut_message("mifare_ultralightc_authenticate() failed"));
+
+	// Change the key back to the default key
+	res = mifare_ultralightc_set_key(tag, default_key);
+	cut_assert_equal_int(0, res, cut_message("mifare_ultralightc_set_key() failed"));
+
+	res = mifare_ultralight_disconnect(tag);
+	cut_assert_equal_int(0, res, cut_message("mifare_ultralight_disconnect() failed"));
+
+	res = mifare_ultralight_connect(tag);
+	cut_assert_equal_int(0, res, cut_message("mifare_ultralight_connect() failed"));
+
+	// Test the default key
+	res = mifare_ultralightc_authenticate(tag, default_key);
+	cut_assert_equal_int(0, res, cut_message("mifare_ultralightc_authenticate() failed"));
+
+	mifare_desfire_key_free(default_key);
+	mifare_desfire_key_free(test_key);
+    } else {
+	cut_omit("mifare_ultralightc_set_key() skipped on Ultralight");
+    }
+}