Keystore 2.0: Remove attestKey from KeyChain.

KeyChain supports device id attestation through KeyGenParameterSpec now.
No need to call attest key individually. Also calling attest key
individually is no longer supported by Keystore 2.0 and KeyMint.

Also isBoundKeyAlgorithm returns true.

Test: atest FrameworksServicesTests:DevicePolicyManagerTest
Bug: 171305387
Change-Id: I759fe245b48fe435153fded2c74c9ae99634c146

3 files changed, 60 insertions, 12 deletions

diff --git a/keystore/java/android/security/IKeyChainService.aidl b/keystore/java/android/security/IKeyChainService.aidl
index f708298a2cbd..d00f5f669594 100644
--- a/keystore/java/android/security/IKeyChainService.aidl
+++ b/keystore/java/android/security/IKeyChainService.aidl
@@ -37,8 +37,6 @@ interface IKeyChainService {
     void setUserSelectable(String alias, boolean isUserSelectable);
 
     int generateKeyPair(in String algorithm, in ParcelableKeyGenParameterSpec spec);
-    int attestKey(in String alias, in byte[] challenge, in int[] idAttestationFlags,
-            out KeymasterCertificateChain chain);
     boolean setKeyPairCertificate(String alias, in byte[] userCert, in byte[] certChain);
 
     // APIs used by CertInstaller and DevicePolicyManager
diff --git a/keystore/java/android/security/KeyChain.java b/keystore/java/android/security/KeyChain.java
index 97819c56fd5a..f0bcfe52686d 100644
--- a/keystore/java/android/security/KeyChain.java
+++ b/keystore/java/android/security/KeyChain.java
@@ -44,6 +44,8 @@ import android.os.UserManager;
 import android.security.keystore.AndroidKeyStoreProvider;
 import android.security.keystore.KeyPermanentlyInvalidatedException;
 import android.security.keystore.KeyProperties;
+import android.system.keystore2.Domain;
+import android.system.keystore2.KeyDescriptor;
 import android.util.Log;
 
 import com.android.org.conscrypt.TrustedCertificateStore;
@@ -682,6 +684,33 @@ public final class KeyChain {
         return null;
     }
 
+    /**
+     * This prefix is used to disambiguate grant aliase strings from normal key alias strings.
+     * Technically, a key alias string can use the same prefix. However, a collision does not
+     * lead to privilege escalation, because grants are access controlled in the Keystore daemon.
+     * @hide
+     */
+    public static final String GRANT_ALIAS_PREFIX = "ks2_keychain_grant_id:";
+
+    private static KeyDescriptor getGrantDescriptor(String keyid) {
+        KeyDescriptor result = new KeyDescriptor();
+        result.domain = Domain.GRANT;
+        result.blob = null;
+        result.alias = null;
+        try {
+            result.nspace = Long.parseUnsignedLong(
+                    keyid.substring(GRANT_ALIAS_PREFIX.length()), 16 /* radix */);
+        } catch (NumberFormatException e) {
+            return null;
+        }
+        return result;
+    }
+
+    /** @hide */
+    public static String getGrantString(KeyDescriptor key) {
+        return String.format(GRANT_ALIAS_PREFIX + "%016X", key.nspace);
+    }
+
     /** @hide */
     @Nullable @WorkerThread
     public static KeyPair getKeyPair(@NonNull Context context, @NonNull String alias)
@@ -705,11 +734,23 @@ public final class KeyChain {
 
         if (keyId == null) {
             return null;
+        }
+
+        if (AndroidKeyStoreProvider.isKeystore2Enabled()) {
+            try {
+                return android.security.keystore2.AndroidKeyStoreProvider
+                        .loadAndroidKeyStoreKeyPairFromKeystore(
+                                KeyStore2.getInstance(),
+                                getGrantDescriptor(keyId));
+            } catch (UnrecoverableKeyException | KeyPermanentlyInvalidatedException e) {
+                throw new KeyChainException(e);
+            }
         } else {
             try {
                 return AndroidKeyStoreProvider.loadAndroidKeyStoreKeyPairFromKeystore(
                         KeyStore.getInstance(), keyId, KeyStore.UID_SELF);
-            } catch (RuntimeException | UnrecoverableKeyException | KeyPermanentlyInvalidatedException e) {
+            } catch (RuntimeException | UnrecoverableKeyException
+                    | KeyPermanentlyInvalidatedException e) {
                 throw new KeyChainException(e);
             }
         }
@@ -827,11 +868,8 @@ public final class KeyChain {
     @Deprecated
     public static boolean isBoundKeyAlgorithm(
             @NonNull @KeyProperties.KeyAlgorithmEnum String algorithm) {
-        if (!isKeyAlgorithmSupported(algorithm)) {
-            return false;
-        }
-
-        return KeyStore.getInstance().isHardwareBacked(algorithm);
+        // All supported algorithms are hardware backed. Individual keys may not be.
+        return true;
     }
 
     /** @hide */
diff --git a/keystore/java/android/security/keystore2/AndroidKeyStoreProvider.java b/keystore/java/android/security/keystore2/AndroidKeyStoreProvider.java
index e1011155248e..35059ac929c3 100644
--- a/keystore/java/android/security/keystore2/AndroidKeyStoreProvider.java
+++ b/keystore/java/android/security/keystore2/AndroidKeyStoreProvider.java
@@ -273,10 +273,10 @@ public class AndroidKeyStoreProvider extends Provider {
     /** @hide **/
     @NonNull
     public static KeyPair loadAndroidKeyStoreKeyPairFromKeystore(
-            @NonNull KeyStore2 keyStore, @NonNull String privateKeyAlias, int namespace)
+            @NonNull KeyStore2 keyStore, @NonNull KeyDescriptor descriptor)
             throws UnrecoverableKeyException, KeyPermanentlyInvalidatedException {
         AndroidKeyStoreKey key =
-                loadAndroidKeyStoreKeyFromKeystore(keyStore, privateKeyAlias, namespace);
+                loadAndroidKeyStoreKeyFromKeystore(keyStore, descriptor);
         if (key instanceof AndroidKeyStorePublicKey) {
             AndroidKeyStorePublicKey publicKey = (AndroidKeyStorePublicKey) key;
             return new KeyPair(publicKey, publicKey.getPrivateKey());
@@ -336,7 +336,7 @@ public class AndroidKeyStoreProvider extends Provider {
     @NonNull
     public static AndroidKeyStoreKey loadAndroidKeyStoreKeyFromKeystore(
             @NonNull KeyStore2 keyStore, @NonNull String alias, int namespace)
-            throws UnrecoverableKeyException, KeyPermanentlyInvalidatedException  {
+            throws UnrecoverableKeyException, KeyPermanentlyInvalidatedException {
 
         KeyDescriptor descriptor = new KeyDescriptor();
         if (namespace == KeyProperties.NAMESPACE_APPLICATION) {
@@ -348,6 +348,18 @@ public class AndroidKeyStoreProvider extends Provider {
         }
         descriptor.alias = alias;
         descriptor.blob = null;
+
+        final AndroidKeyStoreKey key = loadAndroidKeyStoreKeyFromKeystore(keyStore, descriptor);
+        if (key instanceof AndroidKeyStorePublicKey) {
+            return ((AndroidKeyStorePublicKey) key).getPrivateKey();
+        } else {
+            return key;
+        }
+    }
+
+    private static AndroidKeyStoreKey loadAndroidKeyStoreKeyFromKeystore(
+            @NonNull KeyStore2 keyStore, @NonNull KeyDescriptor descriptor)
+            throws UnrecoverableKeyException, KeyPermanentlyInvalidatedException {
         KeyEntryResponse response = null;
         try {
             response = keyStore.getKeyEntry(descriptor);
@@ -397,7 +409,7 @@ public class AndroidKeyStoreProvider extends Provider {
                 keymasterAlgorithm == KeymasterDefs.KM_ALGORITHM_EC) {
             return makeAndroidKeyStorePublicKeyFromKeyEntryResponse(descriptor, response.metadata,
                     new KeyStoreSecurityLevel(response.iSecurityLevel),
-                    keymasterAlgorithm).getPrivateKey();
+                    keymasterAlgorithm);
         } else {
             throw new UnrecoverableKeyException("Key algorithm unknown");
         }