diff --git a/nselib/stdnse.lua b/nselib/stdnse.lua
index 7ce532a7c..cad26519d 100644
--- a/nselib/stdnse.lua
+++ b/nselib/stdnse.lua
@@ -135,6 +135,30 @@ function strsplit(pattern, text)
   return list;
 end
 
+--- Generate a random string.
+-- You can either provide your own charset or the function will use
+-- a default one which is [A-Z].
+-- @param len Length of the string we want to generate.
+-- @param charset Charset that will be used to generate the string.
+-- @return A random string of length <code>len</code> consisting of
+-- characters from <code>charset</code> if one was provided, otherwise
+-- <code>charset</code> defaults to [A-Z] letters.
+function generate_random_string(len, charset)
+  local t = {}
+  local ascii_A = 65
+  local ascii_Z = 90
+  if charset then
+    for i=1,len do
+      t[i]=charset[math.random(#charset)]
+    end
+  else
+    for i=1,len do
+      t[i]=string.char(math.random(ascii_A,ascii_Z))
+    end
+  end
+  return table.concat(t)
+end
+
 --- Return a wrapper closure around a socket that buffers socket reads into
 -- chunks separated by a pattern.
 --