README.md

RandomPasswordBuilder

Description

This is just another .NET library generating random strings.

The library was developed as a side product.

It includes the class DrLSDee.Text.RandomPasswordBuilder.PasswordBuilder providing a method to generate passwords that are guaranteed to include all specified character categories.

Unlike some others, the class method PasswordBuilder.Next() does not simply repeat random string generation until one finally meets the password requirements.

An instance uses a dictionary, where keys are character categories and values are character sets corresponding to those categories.

When generating next random string, the method takes from 1 to N characters from each category, stores in the list and, finally, shuffles the list and builds a string.

This way, for a single password that is guaranteed to meet the requirements, the method is always called only once.

Character categories are:

• Decimal digits from 0 to 9;
• Latin uppercase letters from A to Z;
• Latin lowercase letters from a to z'
• And special printable characters such as dot, comma, slashes, parentheses etc.: '-!"#$%&()*,./:;?@[]^_{|}~+<=>

The list of special characters is taken from this Microsoft article

Optionally, you can specify lists of additional characters to add or exclude, or both.

The class has a flag that excludes XML-unsafe characters: "'<>&; you can use it if you plan to use generated strings in XML documents, e.g. when sending SOAP requests.

Limitations

The library currently uses .NET Framework 4.8, not .NET or .NET Core.

This is because the core product is being developed for use on general Windows/Windows Server installations where newer runtimes may not be installed.

But feel free to fork this project and adapt it for runtime you prefer.

Examples

You can also see an example of usage in the PowerShell cmdlet class GetRandomPasswordCmdlet.cs

using DrLSDee.Text.RandomPasswordBuilder;
using System;

namespace Com.Contoso.Example
{
    public static class TestClass
    {
        public static int Count { get; set; } = 10;
        public static void Main()
        {
            using (PasswordBuilder builder = new PasswordBuilder())
            {
                for (int i = 0; i < Count; i++)
                {
                    Console.WriteLine($"Password {i + 1} of {Count}: {builder.Next()}");
                }
            }
        }
    }
}

It shows something like this:

Password 1 of 10: 164Ls:7jT
Password 2 of 10: 84k8N50Q~
Password 3 of 10: VB26>040~s]q
Password 4 of 10: 2U:kEgS7V
Password 5 of 10: sPr_N9VBM9qjaL[
Password 6 of 10: 1cKGAE~MH6}j1;WC
Password 7 of 10: f3?CC7GHE
Password 8 of 10: 3bQd22;3R761pn~u
Password 9 of 10: KJTUO13z4EH3H(t
Password 10 of 10: #FWs3-5v7.558

This example is not quite correct, because when the static method Main() completes, it disposes a temporary instance of PasswordBuilder.

And because both the class and the method are static and do not provide the way to re-create an instance of PasswordBuilder, you can only call the Main() once.

So be careful with disposable objects.