Consolidate Keystore alias prefixes.

Currently, the keystore SPI assigns different prefixes to user key
entries depending on the algorithm. Symmetric keys (secret keys) get
the prefix USERSKEY_ and asymmetric keys (private keys) get the
prefix USERPKEY_. This distinction is superfluous, as the information
can always be retrieved from the key characteristics. Also moving
forward it is desirable to be able to import keys the nature
of which is not known a priori. In these cases the prefix cannot be
chosen meaningfully.

This patch deprecates one of the prefixes (i.e. USERSKEY_) and uses
the other for both types of keys. Legacy keys with the old prefix
can still be used, but all new keys will have the prefix USERPKEY_.

Bug: 63931634
Test: CTS test and Manual upgrade test with KeyStoreTool app
      Also performed upgrade test with device PIN set
Change-Id: I5b4bb0b0d2b82c276659d55b862150326bb68d5d

1 files changed, 14 insertions, 20 deletions

diff --git a/keystore/java/android/security/Credentials.java b/keystore/java/android/security/Credentials.java
index 6830a7487dbc..57db20be1145 100644
--- a/keystore/java/android/security/Credentials.java
+++ b/keystore/java/android/security/Credentials.java
@@ -60,10 +60,12 @@ public class Credentials {
     /** Key prefix for user certificates. */
     public static final String USER_CERTIFICATE = "USRCERT_";
 
-    /** Key prefix for user private keys. */
+    /** Key prefix for user private and secret keys. */
     public static final String USER_PRIVATE_KEY = "USRPKEY_";
 
-    /** Key prefix for user secret keys. */
+    /** Key prefix for user secret keys.
+     *  @deprecated use {@code USER_PRIVATE_KEY} for this category instead.
+     */
     public static final String USER_SECRET_KEY = "USRSKEY_";
 
     /** Key prefix for VPN. */
@@ -235,8 +237,7 @@ public class Credentials {
          * Make sure every type is deleted. There can be all three types, so
          * don't use a conditional here.
          */
-        return deletePrivateKeyTypeForAlias(keystore, alias, uid)
-                & deleteSecretKeyTypeForAlias(keystore, alias, uid)
+        return deleteUserKeyTypeForAlias(keystore, alias, uid)
                 & deleteCertificateTypesForAlias(keystore, alias, uid);
     }
 
@@ -264,34 +265,27 @@ public class Credentials {
     }
 
     /**
-     * Delete private key for a particular {@code alias}.
-     * Returns {@code true} if the entry no longer exists.
-     */
-    static boolean deletePrivateKeyTypeForAlias(KeyStore keystore, String alias) {
-        return deletePrivateKeyTypeForAlias(keystore, alias, KeyStore.UID_SELF);
-    }
-
-    /**
-     * Delete private key for a particular {@code alias}.
+     * Delete user key for a particular {@code alias}.
      * Returns {@code true} if the entry no longer exists.
      */
-    static boolean deletePrivateKeyTypeForAlias(KeyStore keystore, String alias, int uid) {
-        return keystore.delete(Credentials.USER_PRIVATE_KEY + alias, uid);
+    public static boolean deleteUserKeyTypeForAlias(KeyStore keystore, String alias) {
+        return deleteUserKeyTypeForAlias(keystore, alias, KeyStore.UID_SELF);
     }
 
     /**
-     * Delete secret key for a particular {@code alias}.
+     * Delete user key for a particular {@code alias}.
      * Returns {@code true} if the entry no longer exists.
      */
-    public static boolean deleteSecretKeyTypeForAlias(KeyStore keystore, String alias) {
-        return deleteSecretKeyTypeForAlias(keystore, alias, KeyStore.UID_SELF);
+    public static boolean deleteUserKeyTypeForAlias(KeyStore keystore, String alias, int uid) {
+        return keystore.delete(Credentials.USER_PRIVATE_KEY + alias, uid) ||
+                keystore.delete(Credentials.USER_SECRET_KEY + alias, uid);
     }
 
     /**
-     * Delete secret key for a particular {@code alias}.
+     * Delete legacy prefixed entry for a particular {@code alias}
      * Returns {@code true} if the entry no longer exists.
      */
-    public static boolean deleteSecretKeyTypeForAlias(KeyStore keystore, String alias, int uid) {
+    public static boolean deleteLegacyKeyForAlias(KeyStore keystore, String alias, int uid) {
         return keystore.delete(Credentials.USER_SECRET_KEY + alias, uid);
     }
 }