ThinkSharp.Licensing

Introduction

ThinkSharp.Licensing is a simple library with fluent API for creating and verifying signed licenses. It provides the following functionallities:

• Creation / verification of hardware identifiers (Windows only)
• Creation / verification of serial numbers
• Creation / verification of signed licenses

Installation

ThinkSharp.Licensing can be installed via Nuget

  Install-Package ThinkSharp.Licensing 

API Reference

Singed License

The class SignedLicense encapsulates some license related information and a signature for verifying it. The license can be serialized / deserialized for storing it on the client. It has following public properties:

• IssueDate: date of the issuing (when the license was created)
• ExpirationDate: date of the expiration (may be DateTime.MaxValue for licenses without expiration)
• SerialNumber Optional: a serial number (See class SerialNumber below)
• Properties IDictionary<string, string> with custom key value pairs

The static Lic class is the entry point for the fluent API that allows to work with signed licenses. It has the following static properties:

• Lic.Builder: Object for creating signed license objects
• Lic.Verifyer: Object for verifiying serialized signed licenses and deserialize it.
• Lic.KeyGenerator: Object for creating private/public key pairs to use for signing

Usage

Create signed licenses

SignedLicense license = Lic.Builder
    .WithRsaPrivateKey(pk)                                           // .WithSigner(ISigner)
    .WithHardwareIdentifier(HardwareIdentifier.ForCurrentComputer()) // .WithoutHardwareIdentifier()
    .WithSerialNumber(SerialNumber.Create("ABC"))                    // .WithoutSerialNumber()
    .WithoutExpiration()                                             // .ExpiresIn(TimeSpan), .ExpiresOn(DateTime)
    .WithProperty("Name", "Bill Gates")
    .WithProperty("Company", "Microsoft")                            //... other key value pairs
    .SignAndCreate();

Serialize License

The SignedLicense can be serialized as encrypted base64 encoded string (default):

var encryptedText = license.Serialize();

// FW9JbxVRYW8hcWBVZ3VHbGosEBxfYhlMZmshHHUxGBVbHBksc3
// 9EHywLc2NNaWIsE39YaAxFbXo7BhhSYxwhZmBJYSAGGxkuEhUj
// GREwFw08GxsxEBc8GywLER8jGBAuGRQ1EgEzExc5Ehs0GSAGZU
// BsRRdOQk1tAGptX0RyLSdPRExxQUN1EWxoQ19jWE5nVCAGahJm
// Ek8/GhFwSwY7ehk3Sm4+cRk4EFh4GVkydFh0U0NURAZUWBVnbW
// 9eXQ5JTWtgElI4cHxaBFtEQ2ZBGlFiSmR5bWsuEHRfAENAYx8+
// U09vQmM+Tg5SakFmcmxKFWM9YQ4yR2NVSVdidUwnE1BuS0BLeX
// tbU0tifnNDQ25teVZjcXl2H2pQVnk7QEBTC19FXFRGeGs6T1FX
// SUR0YmprFmknHRA5VBpOeUdYHQ==

or as plain text string:

var plainText = license.SerializePlainText();

// 5BED5GAB-E5TGXKGK-01SI8MFF-7T099W78-SRH4
// SNABC-3RTC-DMW7-9SC1-MAHA
// 08/28/2017 00:00:00
// 12/31/9999 23:59:59
// Name:Bill Gates
// Company:Microsoft
// A3g2b310qk+7Q86jC2Z890ut2x3TuxxbUd+Xs4fMBRv/HmFl9s
// 9PQV/zEcKM1pcjIuFJ/0YS+bAC22xnnbN2e/SJljYMK5N1J/3g
// NYbvcUa+8qokmGRZZsfnURBcCaRwbQTz4KQvT7kaR+rIwuGXF6
// dpViixIKj6D+618t7BRfY=

Verify License

For deserializing the license, the Lic.Verifier has to be used. If the license can not be deserialized hor has no valid signature, an exception is thrown.

SignedLicense license = Lic.Verifier
			   .WithRsaPublicKey(publicKey)       // .WithSigner(ISigner)
		    	   .WithApplicationCode("ABC")        // .WithoutApplicationCode
		           .LoadAndVerify(licenseText);

Create public/private key Pair

A public and private key pair can be generated using the Lic.KeyGenerator object:

SigningKeyPair pair = Lic.KeyGenerator.GenerateRsaKeyPair();
Console.WriteLine(pair.PrivateKey);
Console.WriteLine(pair.PublicKey);

Hardware Identifier

The hardware identifier is an identifier that derives from 4 characteristics of the computer's hardware (processor ID, serial number of BIOS and so on). The identifier may look like:

5BED5GAB-E5TGXKGK-01SI8MFF-7T099W78-SRH4

Each characteristic is encoded in one of first 4 parts (8 charachters). The hardware identifier will be accepted if at least 2 of the 4 characteristics are equal. That ensures, that the license doesn't become invalid if e.g. the processor of the computer changed. The last part (4 characters) is a check sum that can be used to detect errors in the the hardware identifier.

Usage

// Create:
string hardwareIdentifier = HardwareIdentifier.ForCurrentComputer();

// Validate Checksum
if (!HardwareIdentifier.IsCheckSumValid(hardwareIdentifier))
{
    Console.WriteLine("Entered hardware identifier has errors.");
}
        
// Validate for current computer
if (!HardwareIdentifier.IsValidForCurrentComputer(hardwareIdentifier))
{
    Console.WriteLine("Entered license is not valid for this computer.");
}

Serial Number

A serial number is an identifier with an alpha-numeric application code (3 character), some random characters and a check sum. It looks like SNXXX-YYYY-YYYY-YYYY-ZZZ where XXX is the application code, YYYY is the random part and ZZZ is the check sum. E.g.:

SNABC-D156-KYJF-C4M5-1H96    

Usage

// ABC = application code
string serialNumber = SerialNumber.Create("ABC");
    
// Validate CheckSum
if (!SerialNumber.IsCheckSumValid(serialNumber))
{
    Console.WriteLine("Entered serial number is not valid.");
}

License

ThinkSharp.Licensing is released under The MIT license (MIT)

Versioning

We use SemVer for versioning. For the versions available, see the tags on this repository.

Credits

Thanks to Peter-B- for simplifying the project structure and improving compatibility to .Net 5.0.

Donation

If you like ThinkSharp.Licensing and use it in your project(s), feel free to give me a cup of coffee :)