diff --git a/confirmationui/1.0/vts/functional/VtsHalConfirmationUIV1_0TargetTest.cpp b/confirmationui/1.0/vts/functional/VtsHalConfirmationUIV1_0TargetTest.cpp
index 463bb40..278d1f4 100644
--- a/confirmationui/1.0/vts/functional/VtsHalConfirmationUIV1_0TargetTest.cpp
+++ b/confirmationui/1.0/vts/functional/VtsHalConfirmationUIV1_0TargetTest.cpp
@@ -46,13 +46,16 @@
 
 namespace test {
 namespace {
+const support::auth_token_key_t testKey(static_cast<uint8_t>(TestKeyBits::BYTE));
+
 class HMacImplementation {
    public:
-    static support::NullOr<support::array<uint8_t, 32>> hmac256(
-        const uint8_t key[32], std::initializer_list<support::ByteBufferProxy> buffers) {
+    static support::NullOr<support::hmac_t> hmac256(
+        const support::auth_token_key_t& key,
+        std::initializer_list<support::ByteBufferProxy> buffers) {
         HMAC_CTX hmacCtx;
         HMAC_CTX_init(&hmacCtx);
-        if (!HMAC_Init_ex(&hmacCtx, key, 32, EVP_sha256(), nullptr)) {
+        if (!HMAC_Init_ex(&hmacCtx, key.data(), key.size(), EVP_sha256(), nullptr)) {
             return {};
         }
         for (auto& buffer : buffers) {
@@ -60,7 +63,7 @@
                 return {};
             }
         }
-        support::array<uint8_t, 32> result;
+        support::hmac_t result;
         if (!HMAC_Final(&hmacCtx, result.data(), nullptr)) {
             return {};
         }
@@ -70,23 +73,15 @@
 
 using HMacer = support::HMac<HMacImplementation>;
 
-constexpr uint8_t testKeyByte = static_cast<uint8_t>(TestKeyBits::BYTE);
-
 template <typename... Data>
 hidl_vec<uint8_t> testHMAC(const Data&... data) {
-    constexpr uint8_t testKey[32] = {testKeyByte, testKeyByte, testKeyByte, testKeyByte,
-                                     testKeyByte, testKeyByte, testKeyByte, testKeyByte,
-                                     testKeyByte, testKeyByte, testKeyByte, testKeyByte,
-                                     testKeyByte, testKeyByte, testKeyByte, testKeyByte};
-    constexpr uint8_t hmac_size_bytes = sizeof testKey;
-
     auto hmac = HMacer::hmac256(testKey, data...);
     if (!hmac.isOk()) {
         EXPECT_TRUE(false) << "Failed to compute test hmac.  This is a self-test error.";
         return {};
     }
-    hidl_vec<uint8_t> result(hmac_size_bytes);
-    copy(hmac.value().data(), hmac.value().data() + hmac_size_bytes, result.data());
+    hidl_vec<uint8_t> result(hmac.value().size());
+    copy(hmac.value().data(), hmac.value().data() + hmac.value().size(), result.data());
     return result;
 }