How to generate random ID

Sometimes I have to send registration codes for my applications thru fax or postoffice. In that case it is essential to prevent misundestanding of any characted in code.

I use following code for generation passwords with well distinguishable characters (furthermore it works very fast ;) )

function RandomStr (ALen : integer) : string;
// ALen - desired length of password
const Tbl : array [0 .. $1F] of char = (
  '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B',
  'C', 'D', 'E', 'F', 'G', 'H', 'K', 'M', 'N', 'P', 'Q', 'R',
  'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z');
var i, n, k, x, j : integer;
begin
  SetString (Result, nil, ALen);
  n := ALen * 5; // bits in random number
  j := 1;
  while n > 0 do begin
    if n > 30 then k := 30 // work with 32-bits numbers
     else k := n;
    x := Random (1 shl k - 1);
    for i := 1 to k div 5 do begin
      Result [j] := Tbl [x and $1F];
      inc (j);
      x := x ShR 5;
     end;
    dec (n, k)
   end;
end; { of function RandomStr
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