Created libattestation

Move attestation logic from input into separate library. This way Input
and SurfaceFlinger can leverage the same logic

Test: inputflinger_test
Test: attestation_tests
Bug: 155825630
Change-Id: Ia4f65166da8a1c53a9570db59eab602190438696
diff --git a/libs/attestation/tests/HmacKeyManager_test.cpp b/libs/attestation/tests/HmacKeyManager_test.cpp
new file mode 100644
index 0000000..7f7a408
--- /dev/null
+++ b/libs/attestation/tests/HmacKeyManager_test.cpp
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <attestation/HmacKeyManager.h>
+#include <gtest/gtest.h>
+
+namespace android {
+
+class HmacKeyManagerTest : public testing::Test {
+protected:
+    HmacKeyManager mHmacKeyManager;
+};
+
+/**
+ * Ensure that separate calls to sign the same data are generating the same key.
+ * We avoid asserting against INVALID_HMAC. Since the key is random, there is a non-zero chance
+ * that a specific key and data combination would produce INVALID_HMAC, which would cause flaky
+ * tests.
+ */
+TEST_F(HmacKeyManagerTest, GeneratedHmac_IsConsistent) {
+    std::array<uint8_t, 10> data = {4, 3, 5, 1, 8, 5, 2, 7, 1, 8};
+
+    std::array<uint8_t, 32> hmac1 = mHmacKeyManager.sign(data.data(), sizeof(data));
+    std::array<uint8_t, 32> hmac2 = mHmacKeyManager.sign(data.data(), sizeof(data));
+    ASSERT_EQ(hmac1, hmac2);
+}
+
+/**
+ * Ensure that changes in the hmac verification data produce a different hmac.
+ */
+TEST_F(HmacKeyManagerTest, GeneratedHmac_ChangesWhenFieldsChange) {
+    std::array<uint8_t, 10> data = {4, 3, 5, 1, 8, 5, 2, 7, 1, 8};
+    std::array<uint8_t, 32> initialHmac = mHmacKeyManager.sign(data.data(), sizeof(data));
+
+    data[2] = 2;
+    ASSERT_NE(initialHmac, mHmacKeyManager.sign(data.data(), sizeof(data)));
+}
+
+} // namespace android
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