• Introduction
• OCaml implementation
  • Building
  • Running

A password generator following the rules indicated in Rosetta Code.

I copy-paste said rules here for information:

Create a password generation program which will generate passwords containing random ASCII characters from the following groups:

         lower-case letters:  a -> z
         upper-case letters:  A -> Z
                     digits:  0 -> 9
 other printable characters:  !"#$%&'()*+,-./:;<=>?@[]^_{|}~ 
 (the above character list excludes white-space, backslash and grave) 

The generated password(s) must include at least one (of each of the four groups):

   lower-case letter, 
   upper-case letter,
   digit  (numeral),   and 
   one  "other"  character. 

The user must be able to specify the password length and the number of passwords to generate.

The passwords should be displayed or written to a file, one per line.

The randomness should be from a system source or library.

The program should implement a help option or button which should describe the program and options when invoked.

You may also allow the user to specify a seed value, and give the option of excluding visually similar characters.

For example: Il1 O0 5S 2Z where the characters are:

• capital eye, lowercase ell, the digit one
• capital oh, the digit zero
• the digit five, capital ess
• the digit two, capital zee

I consider my code is not worth being added to the Rosetta Code site... Maybe later, in a few months or in a few years...

I chose to implement the program in OCaml, just because... well... because... why not?

Just one word here: I don't use external libraries such as Core or Batteries, because I want to learn the language, and sticking to the default library provided by the standard package makes things a bit harder, but also forces to think a bit more...

If it's too easy, it ain't that funny. -- Author: Me.

An Oasis file is provided:

$ cd ocaml
$ oasis setup
$ ocaml setup.ml -configure
$ ocaml setup.ml -build

A file (a symbolic link, actually) named pwdgen.native (or pwdgen.byte depending on your system) should be present now.

The program can also be built by hand using ocamlbuild:

$ cd ocaml/src
$ ocamlbuild pwdgen.native

Information is shown using the --help option:

$ ./pwdgen.native --help
./pwdgen.native: Generate random passwords.
usage: ./pwdgen.native [--len <number>] [--num <number>] [--seed <number>] [--safe]
  --len : length of the password (default and minimum = 4)
  --num : number of passwords to be generated (default and minimum = 1)
  --seed : arbitrary number used as a seed for the random number generator
  --safe : exclude visually similar characters
  -help  Display this list of options
  --help  Display this list of options

Quick example:

$ ./pwdgen.native --len 20 --num 5 --safe --seed 987654321
4rtu/M;h_L@@?m{N/#i?
9!;e7T^qFmrL.QvQb^|a
tjn+aWB{v!A<x:%;7jw@
-[:vA3sf4Pk{_f$%jGJW
kuRo_i}$$N#.Hbz9y~3W

Using the same seed generates the same passwords (useful for testing, for example).