Software Implementation Of HDCP Authentication Cipher Based On HDMI

HDMI is a kind of high-definition Multimedia Interface standard, it provides highbandwidth, transmits uncompressed video and audio signal. HDCP protects the transmittedHDMI high-definition digital signal against illegal copy. Base on the analyzing of the HDMIand HDCP specification, this article provided a solution of the HDCP system's core–HDCPCipher. This solution has below importance and specialty:1. It provides a pure software design of the HDCP system's core–HDCP Cipher.Compare with the hardware solution, the software implemented cipher has moreflexibility and cost advantage. This article designed and implemented the overallstructure of the HDCP Cipher's three layer modules. These modules are LFSRmodule, Block Module, Output module, these modules finally used by functions-hdcpBlockCipher, hdcpRekeyChiper, hdcpStreamChiper, which is HDCP Ciphercore algorithm, providing the support for HDCP authentication and stream encryptionand decryption system.2. This software follows the rules of hierarchy and modularity, separates complexembedded software to small modules, the logic between modules is independent,does not have cross function call, also can be built as a share library provideinterfaces to upper level HDCP tools as a validation or compliance tool. The softwarehas good portability and reusability. Meanwhile, the software has the advantage ofbeing able to use as debug tool, it resolve the problem that debug difficulty at HDCP chip hardware logic design phase.3. Since HDCP Cipher make extensive use of bit operations, this implementation use64bit width bit-operation to achieve high speed by exploiting bit-level parallelism,improved the efficiency of the HDCP software Cipher. Compare with no bit-levelparallelism's implementation, the efficiency improve about50times. Get relativelyhigher frame rate at the high resolutionThis software implemented by a program called "hdcpCipher". The input of this programis eight testing devices KSV, coverers each scenarios of HDCP transmitter and HDCPreceiver's combination. The output of this program is encrypted middle state variable and24bit stream encryption/decryption data. All of this software output verified by the testingdata providing by the HDCP specification, got the unique result with the standard output. Thisproved entire software implementation's correctness. At same time, for testing the softwareperformance, it also provides functionality of generate performance data. The software alsocan build as share libraries providing interfaces to upper level HDCP tools.