Validate Ed25519 keys when deserializing them. (#1356)

* Validate Ed25519 keys when deserializing them.

This changes the behavior of the deserialization: before this change,
deserializing an invalid serialization may not fail, but will fail
later when the key is used.

This change makes it fail on deserialization, which
is preferable. We don't expect users to be affected by this, because
such invalid serialization are not used.

* Remove a comment.

* Fix tests that need to be fixed.

Author: juergw

common/src/main/java/org/conscrypt/OpenSslEdDsaPrivateKey.java

@@ -16,6 +16,8 @@
 
 package org.conscrypt;
 
+import java.io.IOException;
+import java.io.ObjectInputStream;
 import java.security.PrivateKey;
 import java.security.spec.EncodedKeySpec;
 import java.security.spec.InvalidKeySpecException;
@@ -117,4 +119,11 @@ public boolean equals(Object o) {
     public int hashCode() {
         return Arrays.hashCode(privateKeyBytes);
     }
+
+    private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
+        stream.defaultReadObject();
+        if (privateKeyBytes.length != ED25519_PRIVATE_KEY_SIZE_BYTES) {
+            throw new IllegalArgumentException("Invalid key size");
+        }
+    }
 }

common/src/main/java/org/conscrypt/OpenSslEdDsaPublicKey.java

@@ -16,6 +16,8 @@
 
 package org.conscrypt;
 
+import java.io.IOException;
+import java.io.ObjectInputStream;
 import java.security.PublicKey;
 import java.security.spec.EncodedKeySpec;
 import java.security.spec.InvalidKeySpecException;
@@ -114,4 +116,11 @@ public int hashCode() {
         }
         return Arrays.hashCode(publicKeyBytes);
     }
+
+    private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
+        stream.defaultReadObject();
+        if (publicKeyBytes.length != ED25519_PUBLIC_KEY_SIZE_BYTES) {
+            throw new IllegalArgumentException("Invalid key size");
+        }
+    }
 }

common/src/test/java/org/conscrypt/EdDsaTest.java

@@ -386,11 +386,7 @@ public void deserializeInvalidPrivateKey_fails() throws Exception {
                 new ByteArrayInputStream(TestUtils.decodeHex(invalidPrivateKeySerialized));
         ObjectInputStream ois = new ObjectInputStream(bais);
 
-        // This creates an invalid private key that can't be used to sign.
-        // It would be better to throw an exception when reading the object.
-        PrivateKey privateKey = (PrivateKey) ois.readObject();
-        Signature signer = Signature.getInstance("Ed25519", conscryptProvider);
-        assertThrows(InvalidKeyException.class, () -> signer.initSign(privateKey));
+        assertThrows(IllegalArgumentException.class, () -> ois.readObject());
     }
 
     @Test
@@ -412,10 +408,6 @@ public void deserializeInvalidPublicKey_fails() throws Exception {
                 new ByteArrayInputStream(TestUtils.decodeHex(invalidPublicKeySerialized));
         ObjectInputStream ois = new ObjectInputStream(bais);
 
-        // This creates an invalid public key that can't be used to verify.
-        // It would be better to throw an exception when reading the object.
-        PublicKey publicKey = (PublicKey) ois.readObject();
-        Signature verifier = Signature.getInstance("Ed25519", conscryptProvider);
-        assertThrows(InvalidKeyException.class, () -> verifier.initVerify(publicKey));
+        assertThrows(IllegalArgumentException.class, () -> ois.readObject());
     }
 }