8286389: Address possibly lossy conversions in jdk.crypto.ec

Reviewed-by: chegar, xuelei

Author: rjernst

src/jdk.crypto.ec/share/classes/sun/security/ec/XDHPublicKeyImpl.java

@@ -76,7 +76,7 @@ public final class XDHPublicKeyImpl extends X509Key implements XECPublicKey {
         // clear the extra bits
         int bitsMod8 = params.getBits() % 8;
         if (bitsMod8 != 0) {
-            int mask = (1 << bitsMod8) - 1;
+            byte mask = (byte) ((1 << bitsMod8) - 1);
             u_arr[0] &= mask;
         }
 

src/jdk.crypto.ec/share/classes/sun/security/ec/ed/EdDSAOperations.java

@@ -256,7 +256,7 @@ private static void prune(byte[] k, int bits, int logCofactor) {
 
         // set the highest bit
         if (highBits == 0) {
-            k[lastByteIndex - 1] |= 0x80;
+            k[lastByteIndex - 1] |= (byte) 0x80;
         } else {
             byte msbMaskOn = (byte) (1 << (highBits - 1));
             k[lastByteIndex] |= msbMaskOn;
@@ -278,7 +278,7 @@ private static byte[] encode(int length, Point p) {
     private static byte[] encode(int length, AffinePoint p) {
         byte[] result = p.getY().asByteArray(length);
         int xLSB = p.getX().asByteArray(1)[0] & 0x01;
-        result[result.length - 1] |= (xLSB << 7);
+        result[result.length - 1] |= (byte) (xLSB << 7);
         return result;
     }
 }