From 40d17c5180c563fe2bf930c2a34d6f9f875a68cb Mon Sep 17 00:00:00 2001
From: "Ryan X. Charles" <ryanxcharles@gmail.com>
Date: Fri, 19 Sep 2014 17:08:44 -0700
Subject: [PATCH] block id

The block id is the reverse of the double sha256 hash of the blockheader.
---
 lib/block.js  |  5 +++++
 test/block.js | 13 +++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/lib/block.js b/lib/block.js
index 3db8f2a..ec0b994 100644
--- a/lib/block.js
+++ b/lib/block.js
@@ -3,6 +3,7 @@ var BufferReader = require('./bufferreader');
 var BufferWriter = require('./bufferwriter');
 var Blockheader = require('./blockheader');
 var Varint = require('./varint');
+var Hash = require('./hash');
 
 var Block = function Block(magicnum, blocksize, blockheader, txsvi, txs) {
   if (!(this instanceof Block))
@@ -93,4 +94,8 @@ Block.prototype.toBufferWriter = function(bw) {
   return bw;
 };
 
+Block.prototype.id = function() {
+  return BufferReader(Hash.sha256sha256(this.blockheader.toBuffer())).reverse().read();
+};
+
 module.exports = Block;
diff --git a/test/block.js b/test/block.js
index 55aa051..5079cfa 100644
--- a/test/block.js
+++ b/test/block.js
@@ -36,6 +36,10 @@ describe('Block', function() {
   var blockhex = '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';
   var blockbuf = new Buffer(blockhex, 'hex');
 
+  var genesishex = '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';
+  var genesisbuf = new Buffer(genesishex, 'hex');
+  var genesisidhex = '000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f';
+
   describe('#set', function() {
 
     it('should set these known values', function() {
@@ -123,4 +127,13 @@ describe('Block', function() {
 
   });
 
+  describe('#id', function() {
+    
+    it('should return the correct id of the genesis block', function() {
+      var block = Block().fromBuffer(genesisbuf);
+      block.id().toString('hex').should.equal(genesisidhex);
+    });
+
+  });
+
 });