A way to obtain KeyStore operation handle from crypto primitives.

This adds AndroidKeyStore.getKeyStoreOperationHandle method which can
be used to obtain the KeyStore operation handle corresponding to the
provided JCA cryto primitive (provided it's backed by
AndroidKeyStore).

Bug: 18088752
Change-Id: Iaa3b6f9b2281b2ec2de8fd5946d353dc7fdb3d2d

1 files changed, 42 insertions, 0 deletions

diff --git a/keystore/java/android/security/AndroidKeyStoreProvider.java b/keystore/java/android/security/AndroidKeyStoreProvider.java
index 39f9d9c6174c..a7c2ddbbe037 100644
--- a/keystore/java/android/security/AndroidKeyStoreProvider.java
+++ b/keystore/java/android/security/AndroidKeyStoreProvider.java
@@ -16,8 +16,12 @@
 
 package android.security;
 
+import java.lang.reflect.Method;
 import java.security.Provider;
 
+import javax.crypto.Cipher;
+import javax.crypto.Mac;
+
 /**
  * A provider focused on providing JCA interfaces for the Android KeyStore.
  *
@@ -71,4 +75,42 @@ public class AndroidKeyStoreProvider extends Provider {
         put("Cipher." + transformation, implClass);
         put("Cipher." + transformation + " SupportedKeyClasses", KeyStoreSecretKey.class.getName());
     }
+
+    /**
+     * Gets the {@link KeyStore} operation handle corresponding to the provided JCA crypto
+     * primitive.
+     *
+     * <p>The following primitives are supported: {@link Cipher} and {@link Mac}.
+     *
+     * @return KeyStore operation handle or {@code null} if the provided primitive's KeyStore
+     *         operation is not in progress.
+     *
+     * @throws IllegalArgumentException if the provided primitive is not supported or is not backed
+     *         by AndroidKeyStore provider.
+     */
+    public static Long getKeyStoreOperationHandle(Object cryptoPrimitive) {
+        if (cryptoPrimitive == null) {
+            throw new NullPointerException();
+        }
+        if ((!(cryptoPrimitive instanceof Mac)) && (!(cryptoPrimitive instanceof Cipher))) {
+            throw new IllegalArgumentException("Unsupported crypto primitive: " + cryptoPrimitive);
+        }
+        Object spi;
+        // TODO: Replace this Reflection based codewith direct invocations once the libcore changes
+        // are in.
+        try {
+            Method getSpiMethod = cryptoPrimitive.getClass().getDeclaredMethod("getSpi");
+            getSpiMethod.setAccessible(true);
+            spi = getSpiMethod.invoke(cryptoPrimitive);
+        } catch (ReflectiveOperationException e) {
+            throw new IllegalArgumentException(
+                    "Unsupported crypto primitive: " + cryptoPrimitive, e);
+        }
+        if (!(spi instanceof KeyStoreCryptoOperation)) {
+            throw new IllegalArgumentException(
+                    "Crypto primitive not backed by Android KeyStore: " + cryptoPrimitive
+                    + ", spi: " + spi);
+        }
+        return ((KeyStoreCryptoOperation) spi).getOperationHandle();
+    }
 }