- Software licensing faces two main attack vectors: cracking (direct code modification) and keygens (generating valid keys by reverse-engineering algorithms).
- Partial Key Verification (PKV) is a legacy algorithm that eventually leaks all subkey parameters, making it insecure by design.
- Modern cryptographic algorithms like Ed25519 (elliptic-curve) and RSA-2048 provide asymmetric signing, preventing key forgery.
- Cryptographic license keys embed data (e.g., email) and a signature, verified using a public key embedded in the application.
- RSA keys are larger but widely supported; Ed25519 offers smaller keys but may have less language support.
- Even with modern cryptography, applications remain vulnerable to cracking, but key generation cannot be compromised without breaking the crypto.
- A licensing server can extend cryptographic keys to support complex models like entitlements, node-locking, and device trials.