diff --git a/PrivateKey.js b/PrivateKey.js
index 2e55af6..decc9c7 100644
--- a/PrivateKey.js
+++ b/PrivateKey.js
@@ -3,8 +3,11 @@ require('classtool');
 function ClassSpec(b) {
   var superclass = b.superclass || require('./util/VersionedData').class();
 
-  function PrivateKey() {
+  //compressed is true if public key is compressed; false otherwise
+  function PrivateKey(version, buf, compressed) {
     PrivateKey.super(this, arguments);
+    if (compressed !== undefined)
+      this.compressed(compressed);
   };
 
   PrivateKey.superclass = superclass;
@@ -13,11 +16,52 @@ function ClassSpec(b) {
   PrivateKey.prototype.validate = function() {
     this.doAsBinary(function() {
       PrivateKey.super(this, 'validate', arguments);
-      if (this.data.length < 32 || this.data.length > 33)
+      if (this.data.length < 32 || (this.data.length > 1+32 && !this.compressed()) || (this.data.length==1+32+1 && this.data[1+32+1-1]!=1) || this.data.length>1+32+1)
         throw new Error('invalid data length');
     });
   };
 
+  // get or set the payload data (as a Buffer object)
+  // overloaded from VersionedData
+  PrivateKey.prototype.payload = function(data) {
+    if(data) {
+      this.doAsBinary(function() {data.copy(this.data,1);});
+      return data;
+    }
+    var buf=this.as('binary');
+    if (buf.length==1+32+1)
+      return buf.slice(1,1+32);
+    else if (buf.length==1+32)
+      return buf.slice(1);
+  };
+
+  // get or set whether the corresponding public key is compressed
+  PrivateKey.prototype.compressed = function(compressed) {
+    if (compressed !== undefined) {
+      this.doAsBinary(function(){
+        var len=1+32+1;
+        if (compressed) {
+          var data=new Buffer(len);
+          this.data.copy(data);
+          this.data=data;
+          this.data[len-1]=1;
+        } else {
+          this.data=this.data.slice(0,len-1);
+        }
+      });
+    }
+    else {
+      var len=1+32+1;
+      var data=this.as('binary');
+      if (data.length==len && data[len-1]==1)
+        return true;
+      else if (data.length==len-1)
+        return false;
+      else
+        throw new Error('invalid private key');
+    }
+  };
+
   return PrivateKey;
 };
 module.defineClass(ClassSpec);
diff --git a/WalletKey.js b/WalletKey.js
index 1fb8c23..0958509 100644
--- a/WalletKey.js
+++ b/WalletKey.js
@@ -4,6 +4,7 @@ function ClassSpec(b) {
 	var coinUtil = require('./util/util');
 	var timeUtil = require('./util/time');
 	var KeyModule = require('./Key');
+	var PrivateKey = require('./PrivateKey').class();
 	var Address = require('./Address').class();
 
 	function WalletKey(cfg) {
@@ -21,9 +22,10 @@ function ClassSpec(b) {
 		var pubKey = this.privKey.public.toString('hex');
 		var pubKeyHash = coinUtil.sha256ripe160(this.privKey.public);
 		var addr = new Address(this.network.addressPubkey, pubKeyHash);
+		var priv = new PrivateKey(this.network.keySecret, this.privKey.private, this.privKey.compressed);
 		var obj = {
 			created: this.created,
-			priv: this.privKey.private.toString('hex'),
+			priv: priv.toString(),
 			pub: pubKey,
 			addr: addr.toString(),
 		};
@@ -34,10 +36,18 @@ function ClassSpec(b) {
 	WalletKey.prototype.fromObj = function(obj) {
 		this.created = obj.created;
 		this.privKey = new KeyModule.Key();
-		this.privKey.private = new Buffer(obj.priv, 'hex');
+		if (obj.priv.length==64) {
+			this.privKey.private = new Buffer(obj.priv,'hex');
+			this.privKey.compressed = true;
+		}
+		else {
+			var priv = new PrivateKey(obj.priv);
+			this.privKey.private = new Buffer(priv.payload());
+			this.privKey.compressed = priv.compressed();
+		}
+		this.privKey.regenerateSync();
 	};
 
 	return WalletKey;
 };
 module.defineClass(ClassSpec);
-
diff --git a/test/PrivateKey.js b/test/PrivateKey.js
new file mode 100644
index 0000000..2bfae56
--- /dev/null
+++ b/test/PrivateKey.js
@@ -0,0 +1,15 @@
+var assert = require('assert');
+var PrivateKey = require('../PrivateKey').class();
+var networks = require('../networks');
+
+describe('PrivateKey', function(){
+  describe('#as', function(){
+    it('should convert hex testnet private key with compressed public key to base58check format', function() {
+      var hex='b9f4892c9e8282028fea1d2667c4dc5213564d41fc5783896a0d843fc15089f3';
+      var buf=new Buffer(hex,'hex');
+      var result='cTpB4YiyKiBcPxnefsDpbnDxFDffjqJob8wGCEDXxgQ7zQoMXJdH';
+      var privkey=new PrivateKey(networks.testnet.keySecret,buf,true);
+      assert.equal(privkey.as('base58'),result);
+    });
+  });
+});
diff --git a/test/basic.js b/test/basic.js
index 3b0f6ff..1ed1148 100644
--- a/test/basic.js
+++ b/test/basic.js
@@ -56,7 +56,7 @@ function test_decode_priv(b58, payload, isTestnet, isCompressed)
 
 	var privkey = new PrivateKey(b58);
 	assert.equal(version, privkey.version());
-	assert.equal(buf.toString(), privkey.payload().toString());
+	assert.equal(buf_pl.toString(), privkey.payload().toString());
 }
 
 function test_decode_pub(b58, payload, isTestnet, addrType)