DES Encryption: Check Length of IV

Encryption operation now checks the length of the IV.  Also changed test to use utf8 instead of HEX because the hex string wasn't valid.

tests/node/tests/operations.mjs

@@ -415,7 +415,7 @@ color: white;
             },
             iv: {
                 string: "threetwo",
-                option: "Hex",
+                option: "utf8",
             },
             mode: "ECB",
         });