[8u] RFR: Backport 8208648: ECC Field Arithmetic Enhancements

[Alvarez, David]

Hi,

Please review this backport of JDK-8181594: Efficient and constant-time modular 
arithmetic

Bug: https://bugs.openjdk.java.net/browse/JDK-8181594
Original: http://hg.openjdk.java.net/jdk/jdk/rev/d213d70182a9
Webrev: http://cr.openjdk.java.net/~phh/8181594/webrev.8u.00/

JDK-8181594 is marked as jdk8u-critical-yes

This is the first of a chain of three patches, JDK-8181594, JDK-8208648 and 
JDK-8208698 I will be sending today

The patch consists only of new files, so there were no conflicts. However, 
jdk/src/share/classes/sun/security/util/math/intpoly/IntegerPolynomial1305.java 
makes use of VarHandle, so I had to replace that part with a ByteBuffer. I’ve 
attached the differences between the original patch and my patch below.

Thanks,
David

--- 
a/src/jdk/src/share/classes/sun/security/util/math/intpoly/IntegerPolynomial1305.java
+++ 
b/src/jdk/src/share/classes/sun/security/util/math/intpoly/IntegerPolynomial1305.java
@@ -26,7 +26,6 @@
package sun.security.util.math.intpoly;

import java.lang.invoke.MethodHandles;
-import java.lang.invoke.VarHandle;
import java.math.BigInteger;
import java.nio.*;

@@ -167,14 +166,13 @@ public class IntegerPolynomial1305 extends 
IntegerPolynomial {
         result[4] = (high >>> 40) + (highByte << 24L);
     }

-    private static final VarHandle AS_LONG_LE = MethodHandles
-        .byteArrayViewVarHandle(long[].class, ByteOrder.LITTLE_ENDIAN);
-
     protected void encode(byte[] v, int offset, int length, byte highByte,
                           long[] result) {
         if (length == 16) {
-            long low = (long) AS_LONG_LE.get(v, offset);
-            long high = (long) AS_LONG_LE.get(v, offset + 8);
+            long low = ByteBuffer.wrap(v, offset, 8)
+                    .order(ByteOrder.LITTLE_ENDIAN).getLong();
+            long high = ByteBuffer.wrap(v, offset + 8, 8)
+                    .order(ByteOrder.LITTLE_ENDIAN).getLong();
             encode(high, low, highByte, result);
         } else {
             super.encode(v, offset, length, highByte, result);