Correct way to obtain JCA private key algorithm.

BUG=509068

Not all RSA/EC JCA private keys (PrivateKey instances) are
instances of RSAPrivateKey/ECPrivateKey.
RSAPrivateKey/ECPrivateKey instances let their clients
access the underlying secret key material. Not all private
keys expose their key material. For example, Android
Keystore and KeyChain private keys do not. In general,
private keys are guarateed to be an instance of PrivateKey
and may be an instance of RSAKey/ECKey if they expose the
domain parameters shared with the corresponding public key
(e.g., RSA modulus or EC parameters). The correct way to
obtain the algorithm of a private key is to invoke
Key.getAlgorithm and compare the result (case-insensitive)
to "RSA" or "EC" (see JCA Standard Names document).

Prior to Android M, private keys returned by KeyChain and
Android Keystore implemented the RSAPrivateKey/ECPrivateKey
interfaces despite not actually exposing the underlying
secret key material (i.e.,
RSAPrivateKey.getPrivateExponent() and ECPrivateKey.getS()
returned null contrary to the contract of these two
interfaces).

Starting with Android M, Android Keystore and KeyChain
private keys no longer implement RSAPrivateKey/ECPrivateKey
interfaces. This broke client certificate handling which
relied on these two interface only to find out the
algorithms of private keys associated with the
certificates.

The fix is thus to find out the algorithm of the private
key using Key.getAlgorithm() instead of instanceof.

Uploading on behalf of klyubin@google.com

Review URL: https://codereview.chromium.org/1230943004

Cr-Commit-Position: refs/heads/master@{#338547}
(cherry picked from commit fb6fecf3aac29f32535677dca039d7e3be872fad)

R=davidben@chromium.org

Review URL: https://codereview.chromium.org/1233143005 .

Cr-Commit-Position: refs/branch-heads/2403@{#516}
Cr-Branched-From: f54b8097a9c45ed4ad308133d49f05325d6c5070-refs/heads/master@{#330231}

1 files changed, 7 insertions, 9 deletions

diff --git a/net/android/java/src/org/chromium/net/DefaultAndroidKeyStore.java b/net/android/java/src/org/chromium/net/DefaultAndroidKeyStore.java
index 3fbf60c..eeb7ab4 100644
--- a/net/android/java/src/org/chromium/net/DefaultAndroidKeyStore.java
+++ b/net/android/java/src/org/chromium/net/DefaultAndroidKeyStore.java
@@ -12,9 +12,7 @@ import java.security.PrivateKey;
 import java.security.Signature;
 import java.security.interfaces.DSAKey;
 import java.security.interfaces.DSAParams;
-import java.security.interfaces.DSAPrivateKey;
 import java.security.interfaces.ECKey;
-import java.security.interfaces.ECPrivateKey;
 import java.security.interfaces.RSAKey;
 import java.security.interfaces.RSAPrivateKey;
 import java.security.spec.ECParameterSpec;
@@ -98,14 +96,13 @@ public class DefaultAndroidKeyStore implements AndroidKeyStore {
         // Hint: Algorithm names come from:
         // http://docs.oracle.com/javase/6/docs/technotes/guides/security/StandardNames.html
         try {
-            if (javaKey instanceof RSAPrivateKey) {
+            String keyAlgorithm = javaKey.getAlgorithm();
+            if ("RSA".equalsIgnoreCase(keyAlgorithm)) {
                 // IMPORTANT: Due to a platform bug, this will throw NoSuchAlgorithmException
                 // on Android 4.0.x and 4.1.x. Fixed in 4.2 and higher.
                 // See https://android-review.googlesource.com/#/c/40352/
                 signature = Signature.getInstance("NONEwithRSA");
-            } else if (javaKey instanceof DSAPrivateKey) {
-                signature = Signature.getInstance("NONEwithDSA");
-            } else if (javaKey instanceof ECPrivateKey) {
+            } else if ("EC".equalsIgnoreCase(keyAlgorithm)) {
                 signature = Signature.getInstance("NONEwithECDSA");
             }
         } catch (NoSuchAlgorithmException e) {
@@ -132,9 +129,10 @@ public class DefaultAndroidKeyStore implements AndroidKeyStore {
     @Override
     public int getPrivateKeyType(AndroidPrivateKey key) {
         PrivateKey javaKey = ((DefaultAndroidPrivateKey) key).getJavaKey();
-        if (javaKey instanceof RSAPrivateKey) return PrivateKeyType.RSA;
-        if (javaKey instanceof DSAPrivateKey) return PrivateKeyType.DSA;
-        if (javaKey instanceof ECPrivateKey) {
+        String keyAlgorithm = javaKey.getAlgorithm();
+        if ("RSA".equalsIgnoreCase(keyAlgorithm)) {
+            return PrivateKeyType.RSA;
+        } else if ("EC".equalsIgnoreCase(keyAlgorithm)) {
             return PrivateKeyType.ECDSA;
         } else {
             return PrivateKeyType.INVALID;