diff --git a/rebootescrow/aidl/default/HadamardUtilsTest.cpp b/rebootescrow/aidl/default/HadamardUtilsTest.cpp
new file mode 100644
index 0000000..e397e76
--- /dev/null
+++ b/rebootescrow/aidl/default/HadamardUtilsTest.cpp
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2019 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 <stdint.h>
+#include <random>
+
+#include <bitset>
+#include <utility>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+#include <HadamardUtils.h>
+
+using namespace aidl::android::hardware::rebootescrow::hadamard;
+
+class HadamardTest : public testing::Test {
+  protected:
+    void SetUp() override {
+        auto ones = std::bitset<ENCODE_LENGTH>{}.set();
+        // Expects 0x4000 to encode as top half as ones, and lower half as zeros. i.e.
+        // [1, 1 .. 1, 0, 0 .. 0]
+        expected_half_size_ = ones << half_size_;
+
+        // Expects 0x1 to encode as interleaved 1 and 0s  i.e. [1, 0, 1, 0 ..]
+        expected_one_ = ones;
+        for (uint32_t i = ENCODE_LENGTH / 2; i >= 1; i /= 2) {
+            expected_one_ ^= (expected_one_ >> i);
+        }
+    }
+
+    uint16_t half_size_ = ENCODE_LENGTH / 2;
+    std::bitset<ENCODE_LENGTH> expected_one_;
+    std::bitset<ENCODE_LENGTH> expected_half_size_;
+};
+
+static void AddError(std::bitset<ENCODE_LENGTH>* corrupted_bits) {
+    // The hadamard code has a hamming distance of ENCODE_LENGTH/2. So we should always be able to
+    // correct the data if less than a quarter of the encoded bits are corrupted.
+    auto corrupted_max = 0.24f * corrupted_bits->size();
+    auto corrupted_num = 0;
+    for (size_t i = 0; i < corrupted_bits->size() && corrupted_num < corrupted_max; i++) {
+        if (random() % 2 == 0) {
+            (*corrupted_bits)[i] = !(*corrupted_bits)[i];
+            corrupted_num += 1;
+        }
+    }
+}
+
+static void EncodeAndDecodeKeys(const std::vector<uint8_t>& key) {
+    auto encoded = EncodeKey(key);
+    ASSERT_EQ(64 * 1024, encoded.size());
+    auto decoded = DecodeKey(encoded);
+    ASSERT_EQ(key, std::vector<uint8_t>(decoded.begin(), decoded.begin() + key.size()));
+}
+
+TEST_F(HadamardTest, Encode_smoke) {
+    ASSERT_EQ(expected_half_size_, EncodeWord(half_size_));
+    ASSERT_EQ(expected_one_, EncodeWord(1));
+    // Check the complement of 1.
+    ASSERT_EQ(~expected_one_, EncodeWord(1u << CODE_K | 1u));
+}
+
+TEST_F(HadamardTest, Decode_smoke) {
+    auto candidate = DecodeWord(expected_half_size_);
+    auto expected = std::pair<int32_t, uint16_t>{ENCODE_LENGTH, half_size_};
+    ASSERT_EQ(expected, candidate.top());
+
+    candidate = DecodeWord(expected_one_);
+    expected = std::pair<int32_t, uint16_t>{ENCODE_LENGTH, 1};
+    ASSERT_EQ(expected, candidate.top());
+}
+
+TEST_F(HadamardTest, Decode_error_correction) {
+    constexpr auto iteration = 10;
+    for (int i = 0; i < iteration; i++) {
+        uint16_t word = random() % (ENCODE_LENGTH * 2);
+        auto corrupted_bits = EncodeWord(word);
+        AddError(&corrupted_bits);
+
+        auto candidate = DecodeWord(corrupted_bits);
+        ASSERT_EQ(word, candidate.top().second);
+    }
+}
+
+TEST_F(HadamardTest, BytesToBitset_smoke) {
+    auto bytes = BitsetToBytes(expected_one_);
+
+    auto read_back = BytesToBitset(bytes);
+    ASSERT_EQ(expected_one_, read_back);
+}
+
+TEST_F(HadamardTest, EncodeAndDecodeKey) {
+    std::vector<uint8_t> KEY_1{
+            0xA5, 0x00, 0xFF, 0x01, 0xA5, 0x5a, 0xAA, 0x55, 0x00, 0xD3, 0x2A,
+            0x8C, 0x2E, 0x83, 0x0E, 0x65, 0x9E, 0x8D, 0xC6, 0xAC, 0x1E, 0x83,
+            0x21, 0xB3, 0x95, 0x02, 0x89, 0x64, 0x64, 0x92, 0x12, 0x1F,
+    };
+    std::vector<uint8_t> KEY_2{
+            0xFF, 0x00, 0x00, 0xAA, 0x5A, 0x19, 0x20, 0x71, 0x9F, 0xFB, 0xDA,
+            0xB6, 0x2D, 0x06, 0xD5, 0x49, 0x7E, 0xEF, 0x63, 0xAC, 0x18, 0xFF,
+            0x5A, 0xA3, 0x40, 0xBB, 0x64, 0xFA, 0x67, 0xC1, 0x10, 0x18,
+    };
+
+    EncodeAndDecodeKeys(KEY_1);
+    EncodeAndDecodeKeys(KEY_2);
+
+    std::vector<uint8_t> key;
+    for (uint8_t i = 0; i < KEY_SIZE_IN_BYTES; i++) {
+        key.push_back(i);
+    };
+    EncodeAndDecodeKeys(key);
+}