diff --git a/lib/errors/spec.js b/lib/errors/spec.js
index 0f8545f..c011378 100644
--- a/lib/errors/spec.js
+++ b/lib/errors/spec.js
@@ -27,7 +27,10 @@ module.exports = [{
     message: format('Invalid network: must be "livenet" or "testnet", got {0}')
   }, {
     name: 'InvalidArgument',
-    message: format('Invalid Argument {0}, {1}'),
+    message: format('Invalid Argument {0}, {1}')
+  }, {
+    name: 'AbstractMethodInvoked',
+    message: format('Abstract Method Invokation: {0}')
   }, {
     name: 'InvalidArgumentType',
     message: format('Invalid Argument for {2}, expected {1} but got ') + '+ typeof arguments[0]',
diff --git a/lib/transaction/input/index.js b/lib/transaction/input/index.js
index 2d25901..ee83cb8 100644
--- a/lib/transaction/input/index.js
+++ b/lib/transaction/input/index.js
@@ -2,4 +2,7 @@
 
 var Input = require('./input');
 
+Input.PublicKeyHash = require('./publicKeyHash');
+Input.ScriptHash = require('./scriptHash');
+
 module.exports = Input;
diff --git a/lib/transaction/input/input.js b/lib/transaction/input/input.js
index fd85364..ad24ca4 100644
--- a/lib/transaction/input/input.js
+++ b/lib/transaction/input/input.js
@@ -1,6 +1,7 @@
 'use strict';
 
 var _ = require('lodash');
+var errors = require('../../errors');
 var BufferWriter = require('../../encoding/bufferwriter');
 var buffer = require('buffer');
 var bufferUtil = require('../../util/buffer');
@@ -31,6 +32,7 @@ Input.prototype._fromObject = function(params) {
   if (_.isString(params.prevTxId) && JSUtil.isHexa(params.prevTxId)) {
     params.prevTxId = new buffer.Buffer(params.prevTxId, 'hex');
   }
+  this.output = params.output;
   this.prevTxId = params.prevTxId;
   this.outputIndex = params.outputIndex;
   this.sequenceNumber = params.sequenceNumber;
@@ -106,4 +108,19 @@ Input.prototype.setScript = function(script) {
   return this;
 };
 
+/**
+ * Retrieve signatures for the provided PrivateKey.
+ *
+ * @param {Transaction} transaction - the transaction to be signed
+ * @param {PrivateKey} privateKey - the private key to use when signing
+ * @param {number} inputIndex - the index of this input in the provided transaction
+ * @param {number} sigType - defaults to Signature.SIGHASH_ALL
+ * @param {Buffer} addressHash - if provided, don't calculate the hash of the
+ *     public key associated with the private key provided
+ * @abstract
+ */
+Input.prototype.getSignatures = function() {
+  throw new errors.AbstractMethodInvoked('Input#getSignatures');
+};
+
 module.exports = Input;
diff --git a/lib/transaction/input/publicKeyHash.js b/lib/transaction/input/publicKeyHash.js
new file mode 100644
index 0000000..9e50418
--- /dev/null
+++ b/lib/transaction/input/publicKeyHash.js
@@ -0,0 +1,31 @@
+'use strict';
+
+var inherits = require('inherits');
+var Input = require('./input');
+var Hash = require('../../crypto/hash');
+var Signature = require('../../crypto/signature');
+var Sighash = require('../sighash');
+var BufferUtil = require('../../util/buffer');
+
+function PublicKeyHashInput() {
+}
+inherits(PublicKeyHashInput, Input);
+
+PublicKeyHashInput.prototype.getSignatures = function(transaction, privateKey, index, sigtype, hashData) {
+  hashData = hashData || Hash.sha256ripemd160(privateKey.publicKey.toBuffer());
+  sigtype = sigtype || Signature.SIGHASH_ALL;
+  if (BufferUtil.equals(hashData, this.output.script.address.hashData)) {
+    return [{
+      address: this.output.script.address,
+      publicKey: privateKey.publicKey,
+      prevTxId: this.txId,
+      outputIndex: this.outputIndex,
+      inputIndex: index,
+      signature: Sighash.sign(transaction, privateKey, sigtype, index, this.output.script),
+      sigtype: sigtype
+    }];
+  }
+  return [];
+};
+
+module.exports = PublicKeyHashInput;
diff --git a/lib/transaction/input/scriptHash.js b/lib/transaction/input/scriptHash.js
new file mode 100644
index 0000000..c7912b5
--- /dev/null
+++ b/lib/transaction/input/scriptHash.js
@@ -0,0 +1,31 @@
+'use strict';
+
+var inherits = require('inherits');
+var Input = require('./input');
+var Hash = require('../../crypto/hash');
+var Signature = require('../../crypto/signature');
+var Sighash = require('../sighash');
+var BufferUtil = require('../../util/buffer');
+
+function ScriptHashInput() {
+}
+inherits(ScriptHashInput, Input);
+
+ScriptHashInput.prototype.getSignatures = function(transaction, privateKey, index, sigtype, hashData) {
+  hashData = hashData || Hash.sha256ripemd160(privateKey.publicKey.toBuffer());
+  sigtype = sigtype || Signature.SIGHASH_ALL;
+  if (BufferUtil.equals(hashData, this.output.script.address.hashData)) {
+    return [{
+      address: this.output.script.address,
+      publicKey: privateKey.publicKey,
+      prevTxId: this.txId,
+      outputIndex: this.outputIndex,
+      inputIndex: index,
+      signature: Sighash.sign(transaction, privateKey, sigtype, index, this.output.script),
+      sigtype: sigtype
+    }];
+  }
+  return [];
+};
+
+module.exports = ScriptHashInput;
diff --git a/lib/transaction/transaction.js b/lib/transaction/transaction.js
index e7ac7d4..36ed537 100644
--- a/lib/transaction/transaction.js
+++ b/lib/transaction/transaction.js
@@ -33,10 +33,8 @@ function Transaction(serialized) {
   this.inputs = [];
   this.outputs = [];
   this._outpoints = [];
-  this._utxos = {};
   this._inputAmount = 0;
   this._outputAmount = 0;
-  this._p2shMap = {};
   this._signatures = {};
 
   if (serialized) {
@@ -228,12 +226,13 @@ Transaction._isNewUtxo = function(utxo) {
 };
 
 Transaction.prototype._fromNewUtxo = function(utxo) {
-  var outpoint = Transaction._makeOutpoint(utxo);
   utxo.address = utxo.address && new Address(utxo.address);
   utxo.script = new Script(util.isHexa(utxo.script) ? new buffer.Buffer(utxo.script, 'hex') : utxo.script);
-  this._utxos[outpoint] = utxo;
-  this._outpoints.push(outpoint);
   this.inputs.push(new Input({
+    output: new Output({
+      script: utxo.script,
+      satoshis: utxo.satoshis
+    }),
     prevTxId: utxo.txId,
     outputIndex: utxo.outputIndex,
     sequenceNumber: DEFAULT_SEQNUMBER,
@@ -254,9 +253,8 @@ Transaction._makeOutpoint = function(data) {
 };
 
 Transaction.prototype.hasAllUtxoInfo = function() {
-  var self = this;
-  return _.all(this._outpoints.map(function(outpoint) {
-    return !!self._utxos[outpoint];
+  return _.all(this.inputs.map(function(input) {
+    return !!input.output;
   }));
 };
 
@@ -328,42 +326,22 @@ Transaction.prototype.sign = function(privKey) {
   return this;
 };
 
-Transaction.prototype._getPrivateKeySignatures = function(privKey) {
+Transaction.prototype._getPrivateKeySignatures = function(privKey, sigtype) {
   privKey = new PrivateKey(privKey);
+  sigtype = sigtype || Signature.SIGHASH_ALL;
   var transaction = this;
   var results = [];
   var hashData = Hash.sha256ripemd160(privKey.publicKey.toBuffer());
-  _.each(this._outpoints, function forEachOutput(outpoint, index) {
-    var utxo = transaction._utxos[outpoint];
-    if ((utxo.address && utxo.address.isPayToPublicKeyHash()) || utxo.script.isPublicKeyHashOut()) {
-      var address = new Address(utxo.address || utxo.script);
-      if (bufferUtil.equals(hashData, address.hashBuffer)) {
-        results.push({
-          publicKey: privKey.publicKey,
-          prevTxId: utxo.txId,
-          outputIndex: utxo.outputIndex,
-          inputIndex: index,
-          signature: Sighash.sign(transaction, privKey, Signature.SIGHASH_ALL, index, utxo.script),
-          sigtype: Signature.SIGHASH_ALL
-        });
-      } else {
-        ;
-      }
-    } else {
-      ;
-    }
+  _.each(this.inputs, function forEachInput(input, index) {
+    _.each(input.getSignatures(transaction, privKey, index, sigtype, hashData), function(signature) {
+      results.push(signature);
+    });
   });
   return results;
 };
 
 Transaction.prototype.applySignature = function(signature) {
-  this.inputs[signature.inputIndex].setScript(
-    Script.buildPublicKeyHashIn(
-      signature.publicKey,
-      signature.signature.toDER(),
-      signature.sigtype
-    )
-  );
+  this.inputs[signature.inputIndex].addSignature(signature);
   return this;
 };