Add API to remove recoverable keys

Test: adb shell am instrument -w -e package com.android.server.locksettings.recoverablekeystore com.android.frameworks.servicestests/android.support.test.runner.AndroidJUnitRunner
Change-Id: Ib69e730467974d34ffe4a700bd6aaf4543a524ae

core/java/com/android/internal/widget/ILockSettings.aidl

@@ -66,6 +66,7 @@ interface ILockSettings {
     void initRecoveryService(in String rootCertificateAlias, in byte[] signedPublicKeyList);
     KeyStoreRecoveryData getRecoveryData(in byte[] account);
     byte[] generateAndStoreKey(String alias);
+    void removeKey(String alias);
     void setSnapshotCreatedPendingIntent(in PendingIntent intent);
     Map getRecoverySnapshotVersions();
     void setServerParameters(long serverParameters);

services/core/java/com/android/server/locksettings/LockSettingsService.java

@@ -2030,6 +2030,11 @@ public class LockSettingsService extends ILockSettings.Stub {
                 sessionId, recoveryKeyBlob, applicationKeys);
     }
 
+    @Override
+    public void removeKey(@NonNull String alias) throws RemoteException {
+        mRecoverableKeyStoreManager.removeKey(alias);
+    }
+
     @Override
     public byte[] generateAndStoreKey(@NonNull String alias) throws RemoteException {
         return mRecoverableKeyStoreManager.generateAndStoreKey(alias);

services/core/java/com/android/server/locksettings/recoverablekeystore/RecoverableKeyStoreManager.java

@@ -411,7 +411,6 @@ public class RecoverableKeyStoreManager {
         int uid = Binder.getCallingUid();
         int userId = UserHandle.getCallingUserId();
 
-
         PlatformEncryptionKey encryptionKey;
         try {
             encryptionKey = mPlatformKeyManager.getEncryptKey(userId);
@@ -433,6 +432,10 @@ public class RecoverableKeyStoreManager {
         }
     }
 
+    public void removeKey(@NonNull String alias) throws RemoteException {
+        mDatabase.removeKey(Binder.getCallingUid(), alias);
+    }
+
     private byte[] decryptRecoveryKey(
             RecoverySessionStorage.Entry sessionEntry, byte[] encryptedClaimResponse)
             throws RemoteException, ServiceSpecificException {

services/core/java/com/android/server/locksettings/recoverablekeystore/storage/RecoverableKeyStoreDb.java

@@ -146,6 +146,19 @@ public class RecoverableKeyStoreDb {
         }
     }
 
+    /**
+     * Removes key with {@code alias} for app with {@code uid}.
+     *
+     * @return {@code true} if deleted a row.
+     */
+    public boolean removeKey(int uid, String alias) {
+        SQLiteDatabase db = mKeyStoreDbHelper.getWritableDatabase();
+        String selection = KeysEntry.COLUMN_NAME_UID + " = ? AND " +
+                KeysEntry.COLUMN_NAME_ALIAS + " = ?";
+        String[] selectionArgs = { Integer.toString(uid), alias };
+        return db.delete(KeysEntry.TABLE_NAME, selection, selectionArgs) > 0;
+    }
+
     /**
      * Returns all statuses for keys {@code uid} and {@code platformKeyGenerationId}.
      *

services/tests/servicestests/src/com/android/server/locksettings/recoverablekeystore/RecoverableKeyStoreManagerTest.java

@@ -192,6 +192,16 @@ public class RecoverableKeyStoreManagerTest {
                 .hasLength(RECOVERABLE_KEY_SIZE_BYTES);
     }
 
+    @Test
+    public void removeKey_removesAKey() throws Exception {
+        int uid = Binder.getCallingUid();
+        mRecoverableKeyStoreManager.generateAndStoreKey(TEST_ALIAS);
+
+        mRecoverableKeyStoreManager.removeKey(TEST_ALIAS);
+
+        assertThat(mRecoverableKeyStoreDb.getKey(uid, TEST_ALIAS)).isNull();
+    }
+
     @Test
     public void startRecoverySession_checksPermissionFirst() throws Exception {
         mRecoverableKeyStoreManager.startRecoverySession(

services/tests/servicestests/src/com/android/server/locksettings/recoverablekeystore/storage/RecoverableKeyStoreDbTest.java

@@ -112,6 +112,22 @@ public class RecoverableKeyStoreDbTest {
                 mRecoverableKeyStoreDb.getKey(2, alias).getNonce());
     }
 
+    @Test
+    public void removeKey_removesAKey() {
+        int userId = 6;
+        int uid = 60001;
+        String alias = "rupertbates";
+        WrappedKey key = new WrappedKey(
+                getUtf8Bytes("nonce1"),
+                getUtf8Bytes("key1"),
+                /*platformKeyGenerationId=*/ 1);
+        mRecoverableKeyStoreDb.insertKey(userId, uid, alias, key);
+
+        assertTrue(mRecoverableKeyStoreDb.removeKey(uid, alias));
+
+        assertNull(mRecoverableKeyStoreDb.getKey(uid, alias));
+    }
+
     @Test
     public void getKey_returnsNullIfNoKey() {
         WrappedKey key = mRecoverableKeyStoreDb.getKey(