diff --git a/CHANGELOG b/CHANGELOG
index b55bd4828..90c5aa191 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,8 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o Enhanced the tohex() function in the NSE stdnse library to support strings
+  and added options to control the formatting. [Sven]
+
 o The http NSE module tries to deal with non-standards-compliant HTTP
   traffic, particularly responses in which the header fields are
   separated by plain LF rather than CRLF. [Jah, Sven]
diff --git a/docs/scripting.xml b/docs/scripting.xml
index ea91314cf..1db13e280 100644
--- a/docs/scripting.xml
+++ b/docs/scripting.xml
@@ -1910,12 +1910,17 @@ if(s) code_to_be_done_on_match end
           </listitem>
         </varlistentry>
         <varlistentry>
-          <term><option>string = stdnse.tohex(n)</option>
+          <term><option>string = stdnse.tohex(s, options)</option>
           </term>
           <listitem>
             <para>
-              Converts the given number, <literal>n</literal>, to a string
-              in a hexadecimal number format (e.g. 10 becomes "a").
+              Converts the given number or string, <literal>s</literal>, to a
+              string in a hexadecimal number format (e.g. 10 becomes "a"). 
+              <literal>options</literal> is a table containing parameters to
+              control the formatting. You may specify <literal>options.separator</literal>
+              which will be used as separator for groups of consecutive bytes.
+              With <literal>options.group</literal> you can control the group
+              length to be used with <literal>options.separator</literal>.
             </para>
           </listitem>
         </varlistentry>
diff --git a/nselib/stdnse.lua b/nselib/stdnse.lua
index 99ee00fea..9e32a8ee6 100644
--- a/nselib/stdnse.lua
+++ b/nselib/stdnse.lua
@@ -5,6 +5,9 @@ local assert = assert;
 local tonumber = tonumber;
 local concat = table.concat;
 local nmap = require"nmap";
+local max = math.max
+local ceil = math.ceil
+local type = type
 
 module(... or "stdnse");
 
@@ -143,10 +146,36 @@ function tooctal(n)
   return ("%o"):format(n)
 end
 
---- Converts the given number, n, to a string in a hexidecimal number format.
---@param n Number to convert.
---@return String in hexidecimal format.
-function tohex(n)
-  assert(tonumber(n), "number expected");
-  return ("%x"):format(n);
+--- encode string or number to hexadecimal
+-- example: stdnse.tohex("abc") => "616263"
+--          stdnse.tohex("abc",{separator=":"}) => "61:62:63"
+--          stdnse.tohex("abc",{separator=":",group=4}) => "61:6263"
+--          stdnse.tohex(123456) => "1e240"
+--          stdnse.tohex(123456,{separator=":"}) => "1:e2:40"
+--          stdnse.tohex(123456,{separator=":",group=4}) => "1:e240"
+--@param s string or number to be encoded
+--@param options table specifiying formatting options
+--@return hexadecimal encoded string
+function tohex( s, options ) 
+  options = options or {}
+  local group = options.group or 2
+  local separator = options.separator or ""
+  local hex
+
+  if type( s ) == 'number' then
+    hex = ("%x"):format(s)
+  elseif type( s ) == 'string' then
+    hex = ("%02x"):rep(#s):format(s:byte(1,#s))
+  else
+    error( "Type not supported in tohex(): " .. type(s), 2 )
+  end
+
+  local fmt_table = {}
+  for i=#hex,1,-group do
+    -- index must be consecutive otherwise table.concat won't work
+    fmt_table[ceil(i/group)] = hex:sub(max(i-group+1,1),i)
+  end
+
+  return concat( fmt_table, separator )
 end
+