US Patent 8483393 Key management system for digital cinema

Key management in a digital cinema system (10, 100 and 1000) occurs by encrypting a feature key associated with encrypted content with a transmission key exchanged with a decryption module (60, 601, 602, 6001, 6002, 6003 and 6004), that serves to decrypt encrypted content. The encrypted feature key undergoes transmission to the decryption module to enable decryption of the encrypted content. In this way, the decryption module will only have the capability of decrypting content based on that module's own key.