According to the invention, a content processing unit for protecting interchip content pathways transporting digital content objects is disclosed. The content processing unit includes a first chip package, a second chip package and a content pathway. The first chip package includes a first body, a first plurality of interconnects, an encryption engine, and a first key storage register capable of storing a first key, and the second chip package includes a second body, a second plurality of interconnects, an encryption engine, and a second key storage register capable of storing a second key. The first key is used by the encryption engine to produce ciphertext content and cannot be overwritten after a programmability period. The first and second key storage registers are non-readable from outside the first body. The second key is used by the decryption engine to produce plaintext content from the ciphertext content. The content pathway couples a first subset of the first plurality and a second subset of the second plurality. The content pathway transports the digital content objects as the ciphertext content.