Symmetric key import for AndroidKeyStore.

AES and HmacSHA256 symmetric keys can now be imported into
AndroidKeyStore. These keys cannot yet be used.

Bug: 18088752
Change-Id: Iad2fd49d15ac4c2d676abe1153f5b5f0b6ff496c
diff --git a/keystore/java/android/security/Credentials.java b/keystore/java/android/security/Credentials.java
index af76d9d..6283e02 100644
--- a/keystore/java/android/security/Credentials.java
+++ b/keystore/java/android/security/Credentials.java
@@ -61,6 +61,9 @@
     /** Key prefix for user private keys. */
     public static final String USER_PRIVATE_KEY = "USRPKEY_";
 
+    /** Key prefix for user secret keys. */
+    public static final String USER_SECRET_KEY = "USRSKEY_";
+
     /** Key prefix for VPN. */
     public static final String VPN = "VPN_";
 
@@ -218,7 +221,8 @@
          * Make sure every type is deleted. There can be all three types, so
          * don't use a conditional here.
          */
-        return keystore.delKey(Credentials.USER_PRIVATE_KEY + alias)
+        return keystore.delete(Credentials.USER_PRIVATE_KEY + alias)
+                | keystore.delete(Credentials.USER_SECRET_KEY + alias)
                 | deleteCertificateTypesForAlias(keystore, alias);
     }
 
@@ -235,4 +239,20 @@
         return keystore.delete(Credentials.USER_CERTIFICATE + alias)
                 | keystore.delete(Credentials.CA_CERTIFICATE + alias);
     }
+
+    /**
+     * Delete private key for a particular {@code alias}.
+     * Returns {@code true} if an entry was was deleted.
+     */
+    static boolean deletePrivateKeyTypeForAlias(KeyStore keystore, String alias) {
+        return keystore.delete(Credentials.USER_PRIVATE_KEY + alias);
+    }
+
+    /**
+     * Delete secret key for a particular {@code alias}.
+     * Returns {@code true} if an entry was was deleted.
+     */
+    static boolean deleteSecretKeyTypeForAlias(KeyStore keystore, String alias) {
+        return keystore.delete(Credentials.USER_SECRET_KEY + alias);
+    }
 }