Keysystem Link - Delta Android

# Generate key on secure build server
keytool -genkeypair -alias update_key -keyalg RSA -keysize 4096 -sigalg SHA256withRSA
Instead of sending the entire license (which may be several kilobytes), the KeySystem implements a delta update. The client sends a hash of its current key state. The license server computes only the differences (deltas) and sends back a minimal patch. This is the "Delta" part of the link.
Patch system/update_engine/verifier.cc:
#include <keystore/keystore_client.h>
bool DeltaVerifier::VerifySignature(const std::string& delta_data, const std::string& signature) 
auto keystore = keystore::KeystoreClient::Create();
auto result = keystore->verify("update_key", delta_data, signature);
return (result == keystore::ResponseCode::NO_ERROR);
 delta android keysystem link