License-Bound Code Encryption

This example makes a protected feature cryptographically dependent on a valid license by combining two Babel technologies: MSIL Code Encryption encrypts the body of a sensitive method, and Babel Licensing stores the decryption password — itself encrypted — inside a signed, hardware-locked license. The Babel Virtual Machine asks the application for the password through a get password hook, which returns it only after the license validates. Removing or bypassing the license check is not enough: without a valid license there is no password, and without the password the encrypted code cannot run.

To use this example you need a site license for Babel Obfuscator (Ultimate, Server or Data Center editions) and Babel Licensing. The source code is available on GitHub:

git clone https://github.com/babelfornet/license-bound-encryption-console-example.git

The sensitive method is marked so Babel keeps the encrypted body inside the assembly and asks for its password at runtime:

[Obfuscation(Feature = "msil encryption:internal=true;source=core;password=...")]
public static int Compute(int a, int b) { /* protected body */ }
 
[Obfuscation(Feature = "msil encryption get password")]
internal static string GetSourcePassword(string source)
{
    // Validate the license and return the password only when it is valid.
}

The code password never appears in clear in the shipped binary. It is written (encrypted with a vendor secret) into a license field, and recovered at runtime only from a validly signed license bound to the current machine. A companion LicenseGenerator project mints the license.

Valid license      ->  Compute(7, 5) = 147   (the encrypted method runs)
Missing / tampered ->  Protected computation blocked (the BVM cannot decrypt the method)

This is the pattern behind Babel’s own feature gating; see License-Bound Code Encryption in the Code Encryption manual for the full explanation, and Feature Based Licenses for a multi-feature variant.