block: use writeUInt32BE for target calculation

src/block.js

@@ -135,12 +135,7 @@ Block.calculateTarget = function (bits) {
 
   var target = new Buffer(32)
   target.fill(0)
-
+  target.writeUInt32BE(mantissa, i - 3)
-  target[i] = mantissa & 0xff
-  target[i - 1] = mantissa >> 8
-  target[i - 2] = mantissa >> 16
-  target[i - 3] = mantissa >> 24
-
   return target
 }
 

test/integration/stealth.js

@@ -51,7 +51,8 @@ function stealthDualSend (e, R, Q) {
 function stealthDualScan (d, R, eG) {
   var eQ = eG.multiply(d) // shared secret
   var c = bigi.fromBuffer(bitcoin.crypto.sha256(eQ.getEncoded()))
-  var vG = new bitcoin.ECPair(null, R.add(G.multiply(c)))
+  var cG = G.multiply(c)
+  var vG = new bitcoin.ECPair(null, R.add(cG))
 
   return vG
 }