Example Bash Cryptographic Verification

This is an example of cryptographically verifying a license key's authenticity using Bash and OpenSSL using your Keygen account's public key. In addition, the license verification script will also extract any embedded tamper-proof data within the key. You can find your public key within your account's settings page.

This example implements the RSA_2048_PKCS1_PSS_SIGN_V2 scheme. Cryptographically verifying signed license keys can be used to implement offline licensing capabilities, as well as to add additional security measures to an online software licensing system.

All that is needed to cryptographically verify a signed license key is your account's public key.

Running the example

First up, add an environment variable containing your public key:

# Your Keygen account's base64 encoded public key
export KEYGEN_PUBLIC_KEY=$(echo -n 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 | base64 --decode)

You can either run each line above within your terminal session before starting the app, or you can add the above contents to your ~/.bashrc file and then run source ~/.bashrc after saving the file.

Next, grant the main.sh bash script execute privileges:

chmod +x main.sh

Then run the script, entering the signed key when prompted:

./main.sh

The license key's authenticity will be verified using RSA-SHA256 with PKCS1 PSS padding. Be sure to copy your public key and license key correctly - your key will fail validation if either of these are copied or included incorrectly. You can find your public key in your account's settings.

Questions?

Reach out at support@keygen.sh if you have any questions or concerns!