Karamba SafeCAN is an in-vehicle network security solution designed to authenticate and encrypt communications between Electronic Control Units (ECUs) in automotive environments. SafeCAN operates by validating the sender identity and data integrity of every message transmitted over in-vehicle networks. It blocks communication from unauthorized ECUs and prevents over-the-air (OTA) malware downloads by authenticating in-vehicle communications. A core design principle of SafeCAN is zero network overhead. Rather than exchanging encryption keys while the vehicle is running, keys are exchanged at the factory. Validation data is embedded in the redundant bits of existing messages, avoiding the need for additional payloads or extra validation messages. SafeCAN is backward compatible, requiring no changes to ECU applications, network protocols, chipsets, or message formats. It is hardware agnostic and supports selective deployment — security can be applied to some ECUs without requiring full network coverage. The solution supports multiple serial data bus types, including CAN, LIN, MOST, and FlexRay, enabling cross-bus communication security. SafeCAN defends against specific network-level threats including ECU impersonation, replay attacks, bit flipping, and message tampering. Security is based on parameters sealed and encrypted at the factory, eliminating the need for ongoing updates.