diff --git a/js/encoding/ASN1/hex.js b/js/encoding/ASN1/hex.js
new file mode 100644
index 0000000..f617183
--- /dev/null
+++ b/js/encoding/ASN1/hex.js
@@ -0,0 +1,55 @@
+// Hex JavaScript decoder
+// Copyright (c) 2008 Lapo Luchini <lapo@lapo.it>
+
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+Hex = {};
+
+Hex.decode = function(a) {
+    if (Hex.decoder == undefined) {
+        var hex = "0123456789ABCDEF";
+        var allow = " \f\n\r\t\u00A0\u2028\u2029";
+        var dec = [];
+        for (var i = 0; i < 16; ++i)
+            dec[hex.charAt(i)] = i;
+        hex = hex.toLowerCase();
+        for (var i = 10; i < 16; ++i)
+            dec[hex.charAt(i)] = i;
+        for (var i = 0; i < allow.length; ++i)
+            dec[allow.charAt(i)] = -1;
+        Hex.decoder = dec;
+    }
+    var out = [];
+    var bits = 0, char_count = 0;
+    for (var i = 0; i < a.length; ++i) {
+        var c = a.charAt(i);
+        if (c == '=')
+            break;
+        c = Hex.decoder[c];
+        if (c == -1)
+            continue;
+        if (c == undefined)
+            throw 'Illegal character at offset ' + i;
+        bits |= c;
+        if (++char_count >= 2) {
+            out[out.length] = bits;
+            bits = 0;
+            char_count = 0;
+        } else {
+            bits <<= 4;
+        }
+    }
+    if (char_count)
+        throw "Hex encoding incomplete: 4 bits missing";
+    return out;
+}