[8u] RFR: Backport 8181594: Efficient and constant-time modular arithmetic

[Alvarez, David]

Correction, this is the RFR for 8181594: Efficient and constant-time modular arithmetic

On 2019-06-14, 14:13, "Alvarez, David" <alvdavi at amazon.com> wrote:

    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);