diff --git a/KeyStorage.cpp b/KeyStorage.cpp
index b8000fa..55c1709 100644
--- a/KeyStorage.cpp
+++ b/KeyStorage.cpp
@@ -57,16 +57,14 @@
 static const char* kCurrentVersion = "1";
 static const char* kRmPath = "/system/bin/rm";
 static const char* kSecdiscardPath = "/system/bin/secdiscard";
-static const char* kStretch_none = "none";
-static const char* kStretch_nopassword = "nopassword";
 static const char* kHashPrefix_secdiscardable = "Android secdiscardable SHA512";
 static const char* kHashPrefix_keygen = "Android key wrapping key generation SHA512";
 static const char* kFn_encrypted_key = "encrypted_key";
 static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
 static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";
 static const char* kFn_secdiscardable = "secdiscardable";
-static const char* kFn_stretching = "stretching";
 static const char* kFn_version = "version";
+// Note: old key directories may contain a file named "stretching".
 
 namespace {
 
@@ -412,36 +410,9 @@
     return true;
 }
 
-static std::string getStretching(const KeyAuthentication& auth) {
-    if (auth.usesKeystore()) {
-        return kStretch_nopassword;
-    } else {
-        return kStretch_none;
-    }
-}
-
-static bool stretchSecret(const std::string& stretching, const std::string& secret,
-                          std::string* stretched) {
-    if (stretching == kStretch_nopassword) {
-        if (!secret.empty()) {
-            LOG(WARNING) << "Password present but stretching is nopassword";
-            // Continue anyway
-        }
-        stretched->clear();
-    } else if (stretching == kStretch_none) {
-        *stretched = secret;
-    } else {
-        LOG(ERROR) << "Unknown stretching type: " << stretching;
-        return false;
-    }
-    return true;
-}
-
-static bool generateAppId(const KeyAuthentication& auth, const std::string& stretching,
-                          const std::string& secdiscardable_hash, std::string* appId) {
-    std::string stretched;
-    if (!stretchSecret(stretching, auth.secret, &stretched)) return false;
-    *appId = secdiscardable_hash + stretched;
+static std::string generateAppId(const KeyAuthentication& auth,
+                                 const std::string& secdiscardable_hash) {
+    std::string appId = secdiscardable_hash + auth.secret;
 
     const std::lock_guard<std::mutex> scope_lock(storage_binding_info.guard);
     switch (storage_binding_info.state) {
@@ -449,14 +420,13 @@
             storage_binding_info.state = StorageBindingInfo::State::NOT_USED;
             break;
         case StorageBindingInfo::State::IN_USE:
-            appId->append(storage_binding_info.seed.begin(), storage_binding_info.seed.end());
+            appId.append(storage_binding_info.seed.begin(), storage_binding_info.seed.end());
             break;
         case StorageBindingInfo::State::NOT_USED:
             // noop
             break;
     }
-
-    return true;
+    return appId;
 }
 
 static void logOpensslError() {
@@ -583,10 +553,7 @@
     if (auth.usesKeystore() &&
         !createSecdiscardable(dir + "/" + kFn_secdiscardable, &secdiscardable_hash))
         return false;
-    std::string stretching = getStretching(auth);
-    if (!writeStringToFile(stretching, dir + "/" + kFn_stretching)) return false;
-    std::string appId;
-    if (!generateAppId(auth, stretching, secdiscardable_hash, &appId)) return false;
+    std::string appId = generateAppId(auth, secdiscardable_hash);
     std::string encryptedKey;
     if (auth.usesKeystore()) {
         Keystore keystore;
@@ -638,10 +605,7 @@
     }
     std::string secdiscardable_hash;
     if (!readSecdiscardable(dir + "/" + kFn_secdiscardable, &secdiscardable_hash)) return false;
-    std::string stretching;
-    if (!readFileToString(dir + "/" + kFn_stretching, &stretching)) return false;
-    std::string appId;
-    if (!generateAppId(auth, stretching, secdiscardable_hash, &appId)) return false;
+    std::string appId = generateAppId(auth, secdiscardable_hash);
     std::string encryptedMessage;
     if (!readFileToString(dir + "/" + kFn_encrypted_key, &encryptedMessage)) return false;
     if (auth.usesKeystore()) {