coinbin/js/coin.js

/*
 Coinjs 0.01 beta by OutCast3k{at}gmail.com
 A bitcoin framework loosely based on bitcoinjs.

 http://github.com/OutCast3k/coinjs or http://coinb.in/coinjs
*/

(function () {

	var coinjs = window.coinjs = function () { };

	/* public vars */
	coinjs.pub = 0x00;
	coinjs.priv = 0x80;
	coinjs.multisig = 0x05;
	coinjs.compressed = false;

	/* other vars */
	coinjs.developer = '1CWHWkTWaq1K5hevimJia3cyinQsrgXUvg';

	/* bit(coinb.in) api vars */
	coinjs.host = ('https:'==document.location.protocol?'https://':'http://')+'coinb.in/api/';
	coinjs.uid = '1';
	coinjs.key = '12345678901234567890123456789012';

	/* start of address functions */

	/* generate a private and public keypair, with address and WIF address */
	coinjs.newKeys = function(string){
		var privkey = (string) ? Crypto.SHA256(string) : this.newPrivkey();
		var pubkey = this.newPubkey(privkey);
		return {
			'privkey': privkey,
			'pubkey': pubkey,
			'address': this.pubkey2address(pubkey),
			'wif': this.privkey2wif(privkey),
			'compressed': this.compressed
		};
	}

	/* generate a new random private key */
	coinjs.newPrivkey = function(){
		var x = window.location;
		x += (window.screen.height * window.screen.width * window.screen.colorDepth);
		x += coinjs.random(64);
               	x += (window.screen.availHeight * window.screen.availWidth * window.screen.pixelDepth);
		x += navigator.language;
		x += window.history.length;
		x += coinjs.random(64);
		x += navigator.userAgent;
		x += 'coinb.in';
		x += (Crypto.util.randomBytes(64)).join("");
		x += x.length;
		var dateObj = new Date();
		x += dateObj.getTimezoneOffset();
		x += coinjs.random(64);
		x += x+''+x;
		var r = x;
		for(i=0;i<(x).length;i++){
			r = Crypto.SHA256(r);
		}
		return r;
	}

	/* generate a public key from a private key */
	coinjs.newPubkey = function(hash){
		var privateKeyBigInt = BigInteger.fromByteArrayUnsigned(Crypto.util.hexToBytes(hash));
		var curve = EllipticCurve.getSECCurveByName("secp256k1");

		var curvePt = curve.getG().multiply(privateKeyBigInt);
		var x = curvePt.getX().toBigInteger();
		var y = curvePt.getY().toBigInteger();

		var publicKeyBytes = EllipticCurve.integerToBytes(x, 32);
		publicKeyBytes = publicKeyBytes.concat(EllipticCurve.integerToBytes(y,32));
		publicKeyBytes.unshift(0x04);

		if(coinjs.compressed==true){
			var publicKeyBytesCompressed = EllipticCurve.integerToBytes(x,32)
			if (y.isEven()){
				publicKeyBytesCompressed.unshift(0x02)
			} else {
				publicKeyBytesCompressed.unshift(0x03)
			}
			return Crypto.util.bytesToHex(publicKeyBytesCompressed);
		} else {
			return Crypto.util.bytesToHex(publicKeyBytes);
		}
	}

	/* provide a public key and return address */
	coinjs.pubkey2address = function(h){
		var r = ripemd160(Crypto.SHA256(Crypto.util.hexToBytes(h), {asBytes: true}));
		r.unshift(coinjs.pub);
		var hash = Crypto.SHA256(Crypto.SHA256(r, {asBytes: true}), {asBytes: true});
		var checksum = hash.slice(0, 4);
		return coinjs.base58encode(r.concat(checksum));
	}

	/* provide a scripthash and return address */
	coinjs.scripthash2address = function(h){
		var x = Crypto.util.hexToBytes(h);
		x.unshift(coinjs.pub);
		var r = x;
		r = Crypto.SHA256(Crypto.SHA256(r,{asBytes: true}),{asBytes: true});
		var checksum = r.slice(0,4);
		return coinjs.base58encode(x.concat(checksum));
	}

	/* new multisig address, provide the pubkeys AND required signatures to release the funds */
	coinjs.pubkeys2MultisigAddress = function(pubkeys, required) {
		var s = coinjs.script();
		s.writeOp(81 + (required*1) - 1); //OP_1
		for (var i = 0; i < pubkeys.length; ++i) {
			s.writeBytes(Crypto.util.hexToBytes(pubkeys[i]));
		}
		s.writeOp(81 + pubkeys.length - 1); //OP_1 
		s.writeOp(174); //OP_CHECKMULTISIG
		var x = ripemd160(Crypto.SHA256(s.buffer, {asBytes: true}), {asBytes: true});
		x.unshift(coinjs.multisig);
		var r = x;
		r = Crypto.SHA256(Crypto.SHA256(r, {asBytes: true}), {asBytes: true});
		var checksum = r.slice(0,4);
		var redeemScript = Crypto.util.bytesToHex(s.buffer);
		var address = coinjs.base58encode(x.concat(checksum));
		return {'address':address, 'redeemScript':redeemScript};
	}

	/* provide a privkey and return an WIF  */
	coinjs.privkey2wif = function(h){
		var r = Crypto.util.hexToBytes(h);

		if(coinjs.compressed==true){
			r.push(0x01);
		}

		r.unshift(coinjs.priv);
		var hash = Crypto.SHA256(Crypto.SHA256(r, {asBytes: true}), {asBytes: true});
		var checksum = hash.slice(0, 4);

		return coinjs.base58encode(r.concat(checksum));
	}

	/* convert a wif key back to a private key */
	coinjs.wif2privkey = function(wif){
		var compressed = false;
		var decode = coinjs.base58decode(wif);
		var key = decode.slice(0, decode.length-4);
		key = key.slice(1, key.length);
		if(key.length>=33 && key[key.length-1]==0x01){
			key = key.slice(0, key.length-1);
			compressed = true;
		}
		return {'privkey': Crypto.util.bytesToHex(key), 'compressed':compressed};
	}

	/* convert a wif to a pubkey */
	coinjs.wif2pubkey = function(wif){
		var compressed = coinjs.compressed;
		var r = coinjs.wif2privkey(wif);
		coinjs.compressed = r['compressed'];
		var pubkey = coinjs.newPubkey(r['privkey']);
		coinjs.compressed = compressed;
		return {'pubkey':pubkey,'compressed':r['compressed']};
	}

	/* convert a wif to a address */
	coinjs.wif2address = function(wif){
		var r = coinjs.wif2pubkey(wif);
		return {'address':coinjs.pubkey2address(r['pubkey']), 'compressed':r['compressed']};
	}

	/* decode or validate an address and return the hash */
	coinjs.addressDecode = function(addr){
		try {
			var bytes = coinjs.base58decode(addr);
			var front = bytes.slice(0, bytes.length-4);
			var back = bytes.slice(bytes.length-4);
			var checksum = Crypto.SHA256(Crypto.SHA256(front, {asBytes: true}), {asBytes: true}).slice(0, 4);
			if (checksum+"" == back+"") {
				var o = front.slice(1);
				o.version = front[0];
				return o;
			} else {
				return false;
			}
		} catch(e) {
			return false;
		}
	}

	/* retreive the balance from a given address */
	coinjs.addressBalance = function(address, callback){
		coinjs.ajax(coinjs.host+'?uid='+coinjs.uid+'&key='+coinjs.key+'&setmodule=addresses&request=bal&address='+address+'&r='+Math.random(), callback, "GET");
	}

	/* decompress an compressed public key */
	coinjs.pubkeydecompress = function(pubkey) {
		var curve = EllipticCurve.getSECCurveByName("secp256k1");
		try {
			var pt = curve.curve.decodePointHex(pubkey);
			var x = pt.getX().toBigInteger();
			var y = pt.getY().toBigInteger();

			var publicKeyBytes = EllipticCurve.integerToBytes(x, 32);
			publicKeyBytes = publicKeyBytes.concat(EllipticCurve.integerToBytes(y,32));
			publicKeyBytes.unshift(0x04);
			return Crypto.util.bytesToHex(publicKeyBytes);
		} catch (e) {
			// console.log(e);
			return false;
		}
	}


	/* start of script functions */

	coinjs.script = function(data) {
		var r = {};

		if(!data){
			r.buffer = [];
		} else if ("string" == typeof data) {
			r.buffer = Crypto.util.hexToBytes(data);
		} else if (coinjs.isArray(data)) {
			r.buffer = data;
		} else if (data instanceof coinjs.script) {
			r.buffer = r.buffer;
		} else {
			r.buffer = data;
		}

		/* parse buffer array */
		r.parse = function () {

			var self = this;
			r.chunks = [];
			var i = 0;

			function readChunk(n) {
				self.chunks.push(self.buffer.slice(i, i + n));
				i += n;
			};

			while (i < this.buffer.length) {
				var opcode = this.buffer[i++];
				if (opcode >= 0xF0) {
 					opcode = (opcode << 8) | this.buffer[i++];
				}

				var len;
				if (opcode > 0 && opcode < 76) { //OP_PUSHDATA1
					readChunk(opcode);
				} else if (opcode == 76) { //OP_PUSHDATA1
					len = this.buffer[i++];
					readChunk(len);
				} else if (opcode == 77) { //OP_PUSHDATA2
 					len = (this.buffer[i++] << 8) | this.buffer[i++];
					readChunk(len);
				} else if (opcode == 78) { //OP_PUSHDATA4
					len = (this.buffer[i++] << 24) | (this.buffer[i++] << 16) | (this.buffer[i++] << 8) | this.buffer[i++];
					readChunk(len);
				} else {
					this.chunks.push(opcode);
				}
			}

			return true;
		};

		/* decode the redeemscript of a multisignature transaction */
		r.decodeRedeemScript = function(script){
			var r = false;
			try {
				var s = coinjs.script(Crypto.util.hexToBytes(script));
				if((s.chunks.length>=3) && s.chunks[s.chunks.length-1] == 174){//OP_CHECKMULTISIG
					r = {};
					r.signaturesRequired = s.chunks[0]-80;
					var pubkeys = [];
					for(var i=1;i<s.chunks.length-2;i++){
						pubkeys.push(Crypto.util.bytesToHex(s.chunks[i]));
					}
					r.pubkeys = pubkeys;
					var multi = coinjs.pubkeys2MultisigAddress(pubkeys, r.signaturesRequired);
					r.address = multi['address'];
				}
			} catch(e) {
				// console.log(e);
				r = false;
			}
			return r;
		}

		/* create output script to spend */
		r.spendToScript = function(address){
			var addr = coinjs.addressDecode(address);
			var s = coinjs.script();
			if(addr.version==5){ // multisig address
				s.writeOp(169); //OP_HASH160
				s.writeBytes(addr);
				s.writeOp(135); //OP_EQUAL
			} else { // regular address
				s.writeOp(118); //OP_DUP
				s.writeOp(169); //OP_HASH160
				s.writeBytes(addr);
				s.writeOp(136); //OP_EQUALVERIFY
				s.writeOp(172); //OP_CHECKSIG
			}
			return s;
		}

		/* geneate a (script) pubkey hash of the address - used for when signing */
		r.pubkeyHash = function(address) {
			var addr = coinjs.addressDecode(address);
			var s = coinjs.script();
			s.writeOp(118);//OP_DUP
			s.writeOp(169);//OP_HASH160
			s.writeBytes(addr);
			s.writeOp(136);//OP_EQUALVERIFY
			s.writeOp(172);//OP_CHECKSIG
			return s;
		}

		/* write to buffer */
		r.writeOp = function(op){
			this.buffer.push(op);
			this.chunks.push(op);
			return true;
		}

		/* write bytes to buffer */
		r.writeBytes = function(data){
			if (data.length < 76) {	//OP_PUSHDATA1
				this.buffer.push(data.length);
			} else if (data.length <= 0xff) {
				this.buffer.push(76); //OP_PUSHDATA1
				this.buffer.push(data.length);
			} else if (data.length <= 0xffff) {
				this.buffer.push(77); //OP_PUSHDATA2
				this.buffer.push(data.length & 0xff);
				this.buffer.push((data.length >>> 8) & 0xff);
			} else {
				this.buffer.push(78); //OP_PUSHDATA4
				this.buffer.push(data.length & 0xff);
				this.buffer.push((data.length >>> 8) & 0xff);
				this.buffer.push((data.length >>> 16) & 0xff);
				this.buffer.push((data.length >>> 24) & 0xff);
			}
			this.buffer = this.buffer.concat(data);
			this.chunks.push(data);
			return true;
		}

		r.parse();
		return r;
	}

	/* start of transaction functions */

	/* create a new transaction object */
	coinjs.transaction = function() {

		var r = {};
		r.version = 1;
		r.lock_time = 0;
		r.ins = [];
		r.outs = [];
		r.timestamp = null;
		r.block = null;

		/* add an input to a transaction */
		r.addinput = function(txid, index, script){
			var o = {};
			o.outpoint = {'hash':txid, 'index':index};
			o.script = coinjs.script(script||[]);
			o.sequence = 4294967295;
			return this.ins.push(o);
		}

		/* add an output to a transaction */
		r.addoutput = function(address, value){
			var o = {};
			o.value = new BigInteger('' + Math.round((value*1) * 1e8), 10);
			var s = coinjs.script();
			o.script = s.spendToScript(address);
			return this.outs.push(o);
		}

		/* list unspent transactions */
		r.listUnspent = function(address, callback) {
			coinjs.ajax(coinjs.host+'?uid='+coinjs.uid+'&key='+coinjs.key+'&setmodule=addresses&request=unspent&address='+address+'&r='+Math.random(), callback, "GET");
		}

		/* add unspent to transaction */
		r.addUnspent = function(address, callback){
			var self = this;
			this.listUnspent(address, function(data){
				var s = coinjs.script();
				var pubkeyScript = s.pubkeyHash(address);
				var value = 0;
				var total = 0;
				var x = {};

				if (window.DOMParser) {
					parser=new DOMParser();
					xmlDoc=parser.parseFromString(data,"text/xml");
				} else {
					xmlDoc=new ActiveXObject("Microsoft.XMLDOM");
					xmlDoc.async=false;
					xmlDoc.loadXML(data);
				}

				var unspent = xmlDoc.getElementsByTagName("unspent")[0];

				for(i=1;i<=unspent.childElementCount;i++){
					var u = xmlDoc.getElementsByTagName("unspent_"+i)[0]
					var txhash = (u.getElementsByTagName("tx_hash")[0].childNodes[0].nodeValue).match(/.{1,2}/g).reverse().join("")+'';
					var n = u.getElementsByTagName("tx_output_n")[0].childNodes[0].nodeValue;
					var script = u.getElementsByTagName("script")[0].childNodes[0].nodeValue;

					self.addinput(txhash, n, script);

					value += u.getElementsByTagName("value")[0].childNodes[0].nodeValue*1;
					total++;
				}

				x.unspent = $(xmlDoc).find("unspent");
				x.value = value;
				x.total = total;
				return callback(x);
			});
		}

		/* add unspent and sign */
		r.addUnspentAndSign = function(wif, callback){
			var self = this;
			var address = coinjs.wif2address(wif);
			self.addUnspent(address['address'], function(data){
				self.sign(wif);
				return callback(data);
			});
		}

		/* broadcast a transaction */
		r.broadcast = function(callback, txhex){
			var tx = txhex || this.serialize();
			coinjs.ajax(coinjs.host+'?uid='+coinjs.uid+'&key='+coinjs.key+'&setmodule=bitcoin&request=sendrawtransaction&rawtx='+tx+'&r='+Math.random(), callback, "GET");
		}

		/* generate the transaction hash to sign from a transaction input */
		r.transactionHash = function(index) {
			var clone = coinjs.clone(this);
			if((clone.ins) && clone.ins[index]){
				for (var i = 0; i < clone.ins.length; i++) {
					if(index!=i){
						clone.ins[i].script = coinjs.script();
					}
				}

				var extract = this.extractScriptKey(index);
				clone.ins[index].script = coinjs.script(extract['script']);

				var buffer = Crypto.util.hexToBytes(clone.serialize());
				buffer = buffer.concat(coinjs.numToBytes(parseInt(1),4));
				var hash = Crypto.SHA256(buffer, {asBytes: true});
				var r = Crypto.util.bytesToHex(Crypto.SHA256(hash, {asBytes: true}));
				return r;
			} else {
				return false;
			}
		}

		/* extract the scriptSig, used in the transactionHash() function */
		r.extractScriptKey = function(index) {
			if(this.ins[index]){
				if((this.ins[index].script.chunks.length==5) && this.ins[index].script.chunks[4]==172 && coinjs.isArray(this.ins[index].script.chunks[2])){ //OP_CHECKSIG
					// regular scriptPubkey (not signed)
					return {'type':'scriptpubkey', 'signed':'false', 'signatures':0, 'script': Crypto.util.bytesToHex(this.ins[index].script.buffer)};
				} else if((this.ins[index].script.chunks.length==2) && this.ins[index].script.chunks[0][0]==48){ 
					// regular scriptPubkey (probably signed)
					return {'type':'scriptpubkey', 'signed':'true', 'signatures':1, 'script': Crypto.util.bytesToHex(this.ins[index].script.buffer)};
				} else if (this.ins[index].script.chunks[0]==0 && this.ins[index].script.chunks[this.ins[index].script.chunks.length-1][this.ins[index].script.chunks[this.ins[index].script.chunks.length-1].length-1]==174) { // OP_CHECKMULTISIG
					// multisig script, with signature(s) included
					return {'type':'multisig', 'signed':'true', 'signatures':this.ins[index].script.chunks.length-2, 'script': Crypto.util.bytesToHex(this.ins[index].script.chunks[this.ins[index].script.chunks.length-1])};
				} else if (this.ins[index].script.chunks[0]>=80 && this.ins[index].script.chunks[this.ins[index].script.chunks.length-1]==174) { // OP_CHECKMULTISIG
					// multisig script, without signature!
					return {'type':'multisig', 'signed':'false', 'signatures':0, 'script': Crypto.util.bytesToHex(this.ins[index].script.buffer)};
				} else if (this.ins[index].script.chunks.length==0) {
					// empty
					return {'type':'empty', 'signed':'false', 'signatures':0, 'script': ''};
				} else {
					// something else
					return {'type':'unknown', 'signed':'false', 'signatures':0, 'script':Crypto.util.bytesToHex(this.ins[index].script.buffer)};
				}
			} else {
				return false;
			}
		}

		/* generate a signature from a transaction hash */
		r.transactionSig = function(index, wif){

			function serializeSig(r, s) {
				var rBa = r.toByteArraySigned();
				var sBa = s.toByteArraySigned();

				var sequence = [];
				sequence.push(0x02); // INTEGER
				sequence.push(rBa.length);
				sequence = sequence.concat(rBa);

				sequence.push(0x02); // INTEGER
				sequence.push(sBa.length);
				sequence = sequence.concat(sBa);

				sequence.unshift(sequence.length);
				sequence.unshift(0x30); // SEQUENCE

				return sequence;
			}

			var hash = Crypto.util.hexToBytes(this.transactionHash(index));

			if(hash){
				var rng = new SecureRandom();
				var curve = EllipticCurve.getSECCurveByName("secp256k1");
				var key = coinjs.wif2privkey(wif);
				var priv = BigInteger.fromByteArrayUnsigned(Crypto.util.hexToBytes(key['privkey']));
				var n = curve.getN();
				var e = BigInteger.fromByteArrayUnsigned(hash);
				do {
					var k = new BigInteger(n.bitLength(), rng).mod(n.subtract(BigInteger.ONE)).add(BigInteger.ONE);
					var G = curve.getG();
					var Q = G.multiply(k);
					var r = Q.getX().toBigInteger().mod(n);
				} while (r.compareTo(BigInteger.ZERO) <= 0);

				var s = k.modInverse(n).multiply(e.add(priv.multiply(r))).mod(n);

				var sig = serializeSig(r, s);
				sig.push(parseInt(1, 10));

				return Crypto.util.bytesToHex(sig);
			} else {
				return false;
			}
		}

		/* sign a "standard" input */
		r.signinput = function(index, wif){
			var key = coinjs.wif2pubkey(wif);
			var signature = this.transactionSig(index, wif);
			var s = coinjs.script();
			s.writeBytes(Crypto.util.hexToBytes(signature));
			s.writeBytes(Crypto.util.hexToBytes(key['pubkey']));
			this.ins[index].script = s;
			return true;
		}
		
		/* sign a multisig input */
		r.signmultisig = function(index, wif){

			function scriptListPubkey(redeemScript){
				var r = {};
				for(var i=1;i<redeemScript.chunks.length-2;i++){
					r[i] = Crypto.util.hexToBytes(coinjs.pubkeydecompress(Crypto.util.bytesToHex(redeemScript.chunks[i])));
				}
				return r;
			}
	
			function scriptListSigs(scriptSig){
				var r = {};
				if (scriptSig.chunks[0]==0 && scriptSig.chunks[scriptSig.chunks.length-1][scriptSig.chunks[scriptSig.chunks.length-1].length-1]==174){
					for(var i=1;i<scriptSig.chunks.length-1;i++){				
						r[i] = scriptSig.chunks[i];
					}
				}
				return r;
			}

			var redeemScript = (this.ins[index].script.chunks[this.ins[index].script.chunks.length-1]==174) ? this.ins[index].script.buffer : this.ins[index].script.chunks[this.ins[index].script.chunks.length-1];
			var sighash = Crypto.util.hexToBytes(this.transactionHash(index));
			var signature = Crypto.util.hexToBytes(this.transactionSig(index, wif));
			var s = coinjs.script();

			s.writeOp(0);

			if(this.ins[index].script.chunks[this.ins[index].script.chunks.length-1]==174){
				s.writeBytes(signature);

			}  else if (this.ins[index].script.chunks[0]==0 && this.ins[index].script.chunks[this.ins[index].script.chunks.length-1][this.ins[index].script.chunks[this.ins[index].script.chunks.length-1].length-1]==174){
				var pubkeyList = scriptListPubkey(coinjs.script(redeemScript));
				var sigsList = scriptListSigs(this.ins[index].script);
				sigsList[coinjs.countObject(sigsList)+1] = signature;

				for(x in pubkeyList){
					for(y in sigsList){
						if(coinjs.verifySignature(sighash, sigsList[y], pubkeyList[x])){
							s.writeBytes(sigsList[y]);
						}
					}
				}

			}

			s.writeBytes(redeemScript);
			this.ins[index].script = s;
			return true;
		}

		/* sign inputs */
		r.sign = function(wif){
			for (var i = 0; i < this.ins.length; i++) {
				var d = this.extractScriptKey(i);

				var w2a = coinjs.wif2address(wif);
				var script = coinjs.script();
				var pubkeyHash = script.pubkeyHash(w2a['address']);

				if(((d['type'] == 'scriptpubkey' && d['script']==Crypto.util.bytesToHex(pubkeyHash.buffer)) || d['type'] == 'empty') && d['signed'] == "false"){
					this.signinput(i, wif);
				} else if (d['type'] == 'multisig') {
					this.signmultisig(i, wif);
				} else {
					// could not sign
				}
			}
			return this.serialize();
		}

		/* serialize a transaction */
		r.serialize = function(){
			var buffer = [];
			buffer = buffer.concat(coinjs.numToBytes(parseInt(this.version),4));
			buffer = buffer.concat(coinjs.numToVarInt(this.ins.length));

			for (var i = 0; i < this.ins.length; i++) {
				var txin = this.ins[i];
				buffer = buffer.concat(Crypto.util.hexToBytes(txin.outpoint.hash).reverse());
				buffer = buffer.concat(coinjs.numToBytes(parseInt(txin.outpoint.index),4));
				var scriptBytes = txin.script.buffer;
				buffer = buffer.concat(coinjs.numToVarInt(scriptBytes.length));
				buffer = buffer.concat(scriptBytes);
				buffer = buffer.concat(coinjs.numToBytes(parseInt(txin.sequence),4));
			}
			buffer = buffer.concat(coinjs.numToVarInt(this.outs.length));

			for (var i = 0; i < this.outs.length; i++) {
				var txout = this.outs[i];
 				buffer = buffer.concat(coinjs.numToBytes(txout.value,8));
				var scriptBytes = txout.script.buffer;
				buffer = buffer.concat(coinjs.numToVarInt(scriptBytes.length));
				buffer = buffer.concat(scriptBytes);
			}

			buffer = buffer.concat(coinjs.numToBytes(parseInt(this.lock_time),4));
			return Crypto.util.bytesToHex(buffer);
		}

		/* deserialize a transaction */
		r.deserialize = function(buffer){
			if (typeof buffer == "string") {
				buffer = Crypto.util.hexToBytes(buffer)
			}

			var pos = 0;
			var readAsInt = function(bytes) {
				if (bytes == 0) return 0;
				pos++;
				return buffer[pos-1] + readAsInt(bytes-1) * 256;
			}

			var readVarInt = function() {
				pos++;
				if (buffer[pos-1] < 253) {
					return buffer[pos-1];
				}
				return readAsInt(buffer[pos-1] - 251);
			}

			var readBytes = function(bytes) {
				pos += bytes;
				return buffer.slice(pos - bytes, pos);
			}

			var readVarString = function() {
				var size = readVarInt();
				return readBytes(size);
			}

			var obj = new coinjs.transaction();

			obj.version = readAsInt(4);
			var ins = readVarInt();
			for (var i = 0; i < ins; i++) {
				obj.ins.push({
					outpoint: {
						hash: Crypto.util.bytesToHex(readBytes(32).reverse()),
 						index: readAsInt(4)
					},
					script: coinjs.script(readVarString()),
					sequence: readAsInt(4)
				});
			}

			var outs = readVarInt();
			for (var i = 0; i < outs; i++) {
				obj.outs.push({
					value: coinjs.bytesToNum(readBytes(8)),
					script: coinjs.script(readVarString())
				});
			}

 			obj.locktime = readAsInt(4);
			return obj;
		}

		r.size = function(){
			return ((this.serialize()).length/2).toFixed(0);
		}

		return r;
	}

	/* start of signature vertification functions */

	coinjs.verifySignature = function (hash, sig, pubkey) {

		function parseSig (sig) {
			var cursor;
			if (sig[0] != 0x30)
				throw new Error("Signature not a valid DERSequence");

			cursor = 2;
			if (sig[cursor] != 0x02)
				throw new Error("First element in signature must be a DERInteger"); ;

			var rBa = sig.slice(cursor + 2, cursor + 2 + sig[cursor + 1]);

			cursor += 2 + sig[cursor + 1];
			if (sig[cursor] != 0x02)
				throw new Error("Second element in signature must be a DERInteger");

			var sBa = sig.slice(cursor + 2, cursor + 2 + sig[cursor + 1]);

			cursor += 2 + sig[cursor + 1];

			var r = BigInteger.fromByteArrayUnsigned(rBa);
			var s = BigInteger.fromByteArrayUnsigned(sBa);

			return { r: r, s: s };
		}

		var r, s;

		if (coinjs.isArray(sig)) {
			var obj = parseSig(sig);
			r = obj.r;
			s = obj.s;
		} else if ("object" === typeof sig && sig.r && sig.s) {
			r = sig.r;
			s = sig.s;
		} else {
			throw "Invalid value for signature";
		}

		var Q;
		if (coinjs.isArray(pubkey)) {
			var ecparams = EllipticCurve.getSECCurveByName("secp256k1");
			Q = EllipticCurve.PointFp.decodeFrom(ecparams.getCurve(), pubkey);
		} else {
			throw "Invalid format for pubkey value, must be byte array";
		}
		var e = BigInteger.fromByteArrayUnsigned(hash);

		return coinjs.verifySignatureRaw(e, r, s, Q);
	}

	coinjs.verifySignatureRaw = function (e, r, s, Q) {
		var ecparams = EllipticCurve.getSECCurveByName("secp256k1");
		var n = ecparams.getN();
		var G = ecparams.getG();

		if (r.compareTo(BigInteger.ONE) < 0 || r.compareTo(n) >= 0)
			return false;

		if (s.compareTo(BigInteger.ONE) < 0 || s.compareTo(n) >= 0)
			return false;

		var c = s.modInverse(n);

		var u1 = e.multiply(c).mod(n);
		var u2 = r.multiply(c).mod(n);

		var point = G.multiply(u1).add(Q.multiply(u2));

		var v = point.getX().toBigInteger().mod(n);

		return v.equals(r);
	}

	/* start of privates functions */

	/* base58 encode function */
	coinjs.base58encode = function(buffer) {
		var alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
		var base = BigInteger.valueOf(58);

		var bi = BigInteger.fromByteArrayUnsigned(buffer);
		var chars = [];

		while (bi.compareTo(base) >= 0) {
			var mod = bi.mod(base);
			chars.unshift(alphabet[mod.intValue()]);
			bi = bi.subtract(mod).divide(base);
		}

		chars.unshift(alphabet[bi.intValue()]);
		for (var i = 0; i < buffer.length; i++) {
			if (buffer[i] == 0x00) {
				chars.unshift(alphabet[0]);
			} else break;
		}
		return chars.join('');
	}

	/* base58 decode function */
	coinjs.base58decode = function(buffer){
		var alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
		var base = BigInteger.valueOf(58);
		var validRegex = /^[1-9A-HJ-NP-Za-km-z]+$/;

		var bi = BigInteger.valueOf(0);
		var leadingZerosNum = 0;
		for (var i = buffer.length - 1; i >= 0; i--) {
			var alphaIndex = alphabet.indexOf(buffer[i]);
			if (alphaIndex < 0) {
				throw "Invalid character";
			}
			bi = bi.add(BigInteger.valueOf(alphaIndex).multiply(base.pow(buffer.length - 1 - i)));

			if (buffer[i] == "1") leadingZerosNum++;
			else leadingZerosNum = 0;
		}

		var bytes = bi.toByteArrayUnsigned();
		while (leadingZerosNum-- > 0) bytes.unshift(0);
		return bytes;		
	}

	/* raw ajax function to avoid needing bigger frame works like jquery, mootools etc */
	coinjs.ajax = function(u, f, m, a){
		var x = false;
		try{
			x = new ActiveXObject('Msxml2.XMLHTTP')
		} catch(e) {
			try {
				x = new ActiveXObject('Microsoft.XMLHTTP')
			} catch(e) {
				x = new XMLHttpRequest()
			}
		}

		if(x==false) {
			return false;
		}

		x.open(m, u, true);
		x.onreadystatechange=function(){
			if((x.readyState==4) && f)
				f(x.responseText);
		};

		if(m == 'POST'){
			x.setRequestHeader('Content-type','application/x-www-form-urlencoded');
		}

		x.send(a);
	}

	/* clone an object */
	coinjs.clone = function(obj) {
		if(obj == null || typeof(obj) != 'object') return obj;
		var temp = obj.constructor();

		for(var key in obj) {
			if(obj.hasOwnProperty(key)) {
				temp[key] = coinjs.clone(obj[key]);
			}
		}
 		return temp;
	}

	coinjs.numToBytes = function(num,bytes) {
		if (bytes === undefined) bytes = 8;
		if (bytes == 0) { 
			return [];
		} else {
			return [num % 256].concat(coinjs.numToBytes(Math.floor(num / 256),bytes-1));
		}
	}

	coinjs.numToVarInt = function(num) {
		if (num < 253) {
			return [num];
		} else if (num < 65536) {
			return [253].concat(coinjs.numToBytes(num,2));
		} else if (num < 4294967296) {
			return [254].concat(coinjs.numToBytes(num,4));
		} else {
			return [253].concat(coinjs.numToBytes(num,8));
		}
	}

	coinjs.bytesToNum = function(bytes) {
		if (bytes.length == 0) return 0;
		else return bytes[0] + 256 * coinjs.bytesToNum(bytes.slice(1));
	}

	coinjs.isArray = function(o){
		return Object.prototype.toString.call(o) === '[object Array]';
	}

	coinjs.countObject = function(obj){
		var count = 0;
		var i;
		for (i in obj) {
			if (obj.hasOwnProperty(i)) {
				count++;
			}
		}
		return count;
	}

	coinjs.random = function(length) {
		var r = "";
		var l = length || 25;
		var chars = "!$%^&*()_+{}:@~?><|\./;'#][=-abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
		for(x=0;x<l;x++) {
			r += chars.charAt(Math.floor(Math.random() * 62));
		}
		return r;
	}

})();