diff --git a/index.html b/index.html
index 77b012d..8ca5305 100644
--- a/index.html
+++ b/index.html
@@ -77,6 +77,8 @@ <h4 class="modal-title" id="modal-title">Modal title</h4>
 <script src="js/jquery-3.2.1.min.js"></script>
 <script src="js/bootstrap.min.js"></script>
 <script src="js/aes.js"></script>
+<script src="js/sha256.js"></script>
+<script src="js/hmac-sha256.js"></script>
 <script src="js/jsbn.js"></script>
 <script src="js/jsbn2.js"></script>
 <script src="js/base58.js"></script>
diff --git a/js/hardbin.js b/js/hardbin.js
index 87206c4..89ca428 100644
--- a/js/hardbin.js
+++ b/js/hardbin.js
@@ -2,12 +2,38 @@
  * make sure to also load jquery + aes.js
  */
 
+function constant_time_compare(a, b) {
+    if (typeof a !== 'string') {
+        throw "String expected, got " + (typeof a);
+    }
+    if (typeof b !== 'string') {
+        throw "String expected, got " + (typeof b);
+    }
+    if (a.length !== b.length) {
+        return false;
+    }
+    var d = 0;
+    var i = 0;
+    for (i = 0; i < a.length; i++) {
+        d |= a.charCodeAt(i) ^ b.charCodeAt(i);
+    }
+    return d === 0;
+}
+
 function encrypt(data, key) {
-    return CryptoJS.AES.encrypt(data, key).toString();
+    var unauthed = CryptoJS.AES.encrypt(data, key);
+    var mac = CryptoJS.HmacSHA256(unauthed, key);
+    return mac.toString() + unauthed.toString();
 }
 
 function decrypt(data, key) {
-    return CryptoJS.AES.decrypt(data, key).toString(CryptoJS.enc.Utf8);
+    var mac = data.substring(0, 32);
+    var message = data.substring(32);
+    var calc = CryptoJS.HmacSHA256(message, key).toString();
+    if (!constant_time_compare(calc, mac)) {
+        throw "Invalid message authentication code!";
+    }
+    return CryptoJS.AES.decrypt(message, key).toString(CryptoJS.enc.Utf8);
 }
 
 function generate_key() {
diff --git a/js/hmac-sha256.js b/js/hmac-sha256.js
new file mode 100644
index 0000000..c822cfb
--- /dev/null
+++ b/js/hmac-sha256.js
@@ -0,0 +1,18 @@
+/*
+CryptoJS v3.1.2
+code.google.com/p/crypto-js
+(c) 2009-2013 by Jeff Mott. All rights reserved.
+code.google.com/p/crypto-js/wiki/License
+*/
+var CryptoJS=CryptoJS||function(h,s){var f={},g=f.lib={},q=function(){},m=g.Base={extend:function(a){q.prototype=this;var c=new q;a&&c.mixIn(a);c.hasOwnProperty("init")||(c.init=function(){c.$super.init.apply(this,arguments)});c.init.prototype=c;c.$super=this;return c},create:function(){var a=this.extend();a.init.apply(a,arguments);return a},init:function(){},mixIn:function(a){for(var c in a)a.hasOwnProperty(c)&&(this[c]=a[c]);a.hasOwnProperty("toString")&&(this.toString=a.toString)},clone:function(){return this.init.prototype.extend(this)}},
+r=g.WordArray=m.extend({init:function(a,c){a=this.words=a||[];this.sigBytes=c!=s?c:4*a.length},toString:function(a){return(a||k).stringify(this)},concat:function(a){var c=this.words,d=a.words,b=this.sigBytes;a=a.sigBytes;this.clamp();if(b%4)for(var e=0;e<a;e++)c[b+e>>>2]|=(d[e>>>2]>>>24-8*(e%4)&255)<<24-8*((b+e)%4);else if(65535<d.length)for(e=0;e<a;e+=4)c[b+e>>>2]=d[e>>>2];else c.push.apply(c,d);this.sigBytes+=a;return this},clamp:function(){var a=this.words,c=this.sigBytes;a[c>>>2]&=4294967295<<
+32-8*(c%4);a.length=h.ceil(c/4)},clone:function(){var a=m.clone.call(this);a.words=this.words.slice(0);return a},random:function(a){for(var c=[],d=0;d<a;d+=4)c.push(4294967296*h.random()|0);return new r.init(c,a)}}),l=f.enc={},k=l.Hex={stringify:function(a){var c=a.words;a=a.sigBytes;for(var d=[],b=0;b<a;b++){var e=c[b>>>2]>>>24-8*(b%4)&255;d.push((e>>>4).toString(16));d.push((e&15).toString(16))}return d.join("")},parse:function(a){for(var c=a.length,d=[],b=0;b<c;b+=2)d[b>>>3]|=parseInt(a.substr(b,
+2),16)<<24-4*(b%8);return new r.init(d,c/2)}},n=l.Latin1={stringify:function(a){var c=a.words;a=a.sigBytes;for(var d=[],b=0;b<a;b++)d.push(String.fromCharCode(c[b>>>2]>>>24-8*(b%4)&255));return d.join("")},parse:function(a){for(var c=a.length,d=[],b=0;b<c;b++)d[b>>>2]|=(a.charCodeAt(b)&255)<<24-8*(b%4);return new r.init(d,c)}},j=l.Utf8={stringify:function(a){try{return decodeURIComponent(escape(n.stringify(a)))}catch(c){throw Error("Malformed UTF-8 data");}},parse:function(a){return n.parse(unescape(encodeURIComponent(a)))}},
+u=g.BufferedBlockAlgorithm=m.extend({reset:function(){this._data=new r.init;this._nDataBytes=0},_append:function(a){"string"==typeof a&&(a=j.parse(a));this._data.concat(a);this._nDataBytes+=a.sigBytes},_process:function(a){var c=this._data,d=c.words,b=c.sigBytes,e=this.blockSize,f=b/(4*e),f=a?h.ceil(f):h.max((f|0)-this._minBufferSize,0);a=f*e;b=h.min(4*a,b);if(a){for(var g=0;g<a;g+=e)this._doProcessBlock(d,g);g=d.splice(0,a);c.sigBytes-=b}return new r.init(g,b)},clone:function(){var a=m.clone.call(this);
+a._data=this._data.clone();return a},_minBufferSize:0});g.Hasher=u.extend({cfg:m.extend(),init:function(a){this.cfg=this.cfg.extend(a);this.reset()},reset:function(){u.reset.call(this);this._doReset()},update:function(a){this._append(a);this._process();return this},finalize:function(a){a&&this._append(a);return this._doFinalize()},blockSize:16,_createHelper:function(a){return function(c,d){return(new a.init(d)).finalize(c)}},_createHmacHelper:function(a){return function(c,d){return(new t.HMAC.init(a,
+d)).finalize(c)}}});var t=f.algo={};return f}(Math);
+(function(h){for(var s=CryptoJS,f=s.lib,g=f.WordArray,q=f.Hasher,f=s.algo,m=[],r=[],l=function(a){return 4294967296*(a-(a|0))|0},k=2,n=0;64>n;){var j;a:{j=k;for(var u=h.sqrt(j),t=2;t<=u;t++)if(!(j%t)){j=!1;break a}j=!0}j&&(8>n&&(m[n]=l(h.pow(k,0.5))),r[n]=l(h.pow(k,1/3)),n++);k++}var a=[],f=f.SHA256=q.extend({_doReset:function(){this._hash=new g.init(m.slice(0))},_doProcessBlock:function(c,d){for(var b=this._hash.words,e=b[0],f=b[1],g=b[2],j=b[3],h=b[4],m=b[5],n=b[6],q=b[7],p=0;64>p;p++){if(16>p)a[p]=
+c[d+p]|0;else{var k=a[p-15],l=a[p-2];a[p]=((k<<25|k>>>7)^(k<<14|k>>>18)^k>>>3)+a[p-7]+((l<<15|l>>>17)^(l<<13|l>>>19)^l>>>10)+a[p-16]}k=q+((h<<26|h>>>6)^(h<<21|h>>>11)^(h<<7|h>>>25))+(h&m^~h&n)+r[p]+a[p];l=((e<<30|e>>>2)^(e<<19|e>>>13)^(e<<10|e>>>22))+(e&f^e&g^f&g);q=n;n=m;m=h;h=j+k|0;j=g;g=f;f=e;e=k+l|0}b[0]=b[0]+e|0;b[1]=b[1]+f|0;b[2]=b[2]+g|0;b[3]=b[3]+j|0;b[4]=b[4]+h|0;b[5]=b[5]+m|0;b[6]=b[6]+n|0;b[7]=b[7]+q|0},_doFinalize:function(){var a=this._data,d=a.words,b=8*this._nDataBytes,e=8*a.sigBytes;
+d[e>>>5]|=128<<24-e%32;d[(e+64>>>9<<4)+14]=h.floor(b/4294967296);d[(e+64>>>9<<4)+15]=b;a.sigBytes=4*d.length;this._process();return this._hash},clone:function(){var a=q.clone.call(this);a._hash=this._hash.clone();return a}});s.SHA256=q._createHelper(f);s.HmacSHA256=q._createHmacHelper(f)})(Math);
+(function(){var h=CryptoJS,s=h.enc.Utf8;h.algo.HMAC=h.lib.Base.extend({init:function(f,g){f=this._hasher=new f.init;"string"==typeof g&&(g=s.parse(g));var h=f.blockSize,m=4*h;g.sigBytes>m&&(g=f.finalize(g));g.clamp();for(var r=this._oKey=g.clone(),l=this._iKey=g.clone(),k=r.words,n=l.words,j=0;j<h;j++)k[j]^=1549556828,n[j]^=909522486;r.sigBytes=l.sigBytes=m;this.reset()},reset:function(){var f=this._hasher;f.reset();f.update(this._iKey)},update:function(f){this._hasher.update(f);return this},finalize:function(f){var g=
+this._hasher;f=g.finalize(f);g.reset();return g.finalize(this._oKey.clone().concat(f))}})})();
diff --git a/js/sha256.js b/js/sha256.js
new file mode 100644
index 0000000..529db30
--- /dev/null
+++ b/js/sha256.js
@@ -0,0 +1,16 @@
+/*
+CryptoJS v3.1.2
+code.google.com/p/crypto-js
+(c) 2009-2013 by Jeff Mott. All rights reserved.
+code.google.com/p/crypto-js/wiki/License
+*/
+var CryptoJS=CryptoJS||function(h,s){var f={},t=f.lib={},g=function(){},j=t.Base={extend:function(a){g.prototype=this;var c=new g;a&&c.mixIn(a);c.hasOwnProperty("init")||(c.init=function(){c.$super.init.apply(this,arguments)});c.init.prototype=c;c.$super=this;return c},create:function(){var a=this.extend();a.init.apply(a,arguments);return a},init:function(){},mixIn:function(a){for(var c in a)a.hasOwnProperty(c)&&(this[c]=a[c]);a.hasOwnProperty("toString")&&(this.toString=a.toString)},clone:function(){return this.init.prototype.extend(this)}},
+q=t.WordArray=j.extend({init:function(a,c){a=this.words=a||[];this.sigBytes=c!=s?c:4*a.length},toString:function(a){return(a||u).stringify(this)},concat:function(a){var c=this.words,d=a.words,b=this.sigBytes;a=a.sigBytes;this.clamp();if(b%4)for(var e=0;e<a;e++)c[b+e>>>2]|=(d[e>>>2]>>>24-8*(e%4)&255)<<24-8*((b+e)%4);else if(65535<d.length)for(e=0;e<a;e+=4)c[b+e>>>2]=d[e>>>2];else c.push.apply(c,d);this.sigBytes+=a;return this},clamp:function(){var a=this.words,c=this.sigBytes;a[c>>>2]&=4294967295<<
+32-8*(c%4);a.length=h.ceil(c/4)},clone:function(){var a=j.clone.call(this);a.words=this.words.slice(0);return a},random:function(a){for(var c=[],d=0;d<a;d+=4)c.push(4294967296*h.random()|0);return new q.init(c,a)}}),v=f.enc={},u=v.Hex={stringify:function(a){var c=a.words;a=a.sigBytes;for(var d=[],b=0;b<a;b++){var e=c[b>>>2]>>>24-8*(b%4)&255;d.push((e>>>4).toString(16));d.push((e&15).toString(16))}return d.join("")},parse:function(a){for(var c=a.length,d=[],b=0;b<c;b+=2)d[b>>>3]|=parseInt(a.substr(b,
+2),16)<<24-4*(b%8);return new q.init(d,c/2)}},k=v.Latin1={stringify:function(a){var c=a.words;a=a.sigBytes;for(var d=[],b=0;b<a;b++)d.push(String.fromCharCode(c[b>>>2]>>>24-8*(b%4)&255));return d.join("")},parse:function(a){for(var c=a.length,d=[],b=0;b<c;b++)d[b>>>2]|=(a.charCodeAt(b)&255)<<24-8*(b%4);return new q.init(d,c)}},l=v.Utf8={stringify:function(a){try{return decodeURIComponent(escape(k.stringify(a)))}catch(c){throw Error("Malformed UTF-8 data");}},parse:function(a){return k.parse(unescape(encodeURIComponent(a)))}},
+x=t.BufferedBlockAlgorithm=j.extend({reset:function(){this._data=new q.init;this._nDataBytes=0},_append:function(a){"string"==typeof a&&(a=l.parse(a));this._data.concat(a);this._nDataBytes+=a.sigBytes},_process:function(a){var c=this._data,d=c.words,b=c.sigBytes,e=this.blockSize,f=b/(4*e),f=a?h.ceil(f):h.max((f|0)-this._minBufferSize,0);a=f*e;b=h.min(4*a,b);if(a){for(var m=0;m<a;m+=e)this._doProcessBlock(d,m);m=d.splice(0,a);c.sigBytes-=b}return new q.init(m,b)},clone:function(){var a=j.clone.call(this);
+a._data=this._data.clone();return a},_minBufferSize:0});t.Hasher=x.extend({cfg:j.extend(),init:function(a){this.cfg=this.cfg.extend(a);this.reset()},reset:function(){x.reset.call(this);this._doReset()},update:function(a){this._append(a);this._process();return this},finalize:function(a){a&&this._append(a);return this._doFinalize()},blockSize:16,_createHelper:function(a){return function(c,d){return(new a.init(d)).finalize(c)}},_createHmacHelper:function(a){return function(c,d){return(new w.HMAC.init(a,
+d)).finalize(c)}}});var w=f.algo={};return f}(Math);
+(function(h){for(var s=CryptoJS,f=s.lib,t=f.WordArray,g=f.Hasher,f=s.algo,j=[],q=[],v=function(a){return 4294967296*(a-(a|0))|0},u=2,k=0;64>k;){var l;a:{l=u;for(var x=h.sqrt(l),w=2;w<=x;w++)if(!(l%w)){l=!1;break a}l=!0}l&&(8>k&&(j[k]=v(h.pow(u,0.5))),q[k]=v(h.pow(u,1/3)),k++);u++}var a=[],f=f.SHA256=g.extend({_doReset:function(){this._hash=new t.init(j.slice(0))},_doProcessBlock:function(c,d){for(var b=this._hash.words,e=b[0],f=b[1],m=b[2],h=b[3],p=b[4],j=b[5],k=b[6],l=b[7],n=0;64>n;n++){if(16>n)a[n]=
+c[d+n]|0;else{var r=a[n-15],g=a[n-2];a[n]=((r<<25|r>>>7)^(r<<14|r>>>18)^r>>>3)+a[n-7]+((g<<15|g>>>17)^(g<<13|g>>>19)^g>>>10)+a[n-16]}r=l+((p<<26|p>>>6)^(p<<21|p>>>11)^(p<<7|p>>>25))+(p&j^~p&k)+q[n]+a[n];g=((e<<30|e>>>2)^(e<<19|e>>>13)^(e<<10|e>>>22))+(e&f^e&m^f&m);l=k;k=j;j=p;p=h+r|0;h=m;m=f;f=e;e=r+g|0}b[0]=b[0]+e|0;b[1]=b[1]+f|0;b[2]=b[2]+m|0;b[3]=b[3]+h|0;b[4]=b[4]+p|0;b[5]=b[5]+j|0;b[6]=b[6]+k|0;b[7]=b[7]+l|0},_doFinalize:function(){var a=this._data,d=a.words,b=8*this._nDataBytes,e=8*a.sigBytes;
+d[e>>>5]|=128<<24-e%32;d[(e+64>>>9<<4)+14]=h.floor(b/4294967296);d[(e+64>>>9<<4)+15]=b;a.sigBytes=4*d.length;this._process();return this._hash},clone:function(){var a=g.clone.call(this);a._hash=this._hash.clone();return a}});s.SHA256=g._createHelper(f);s.HmacSHA256=g._createHmacHelper(f)})(Math);