// returns PCR values after TPM Reset. // NOTE: PCR_Reset() comamnd always resets PCR contents to zeroes. // TODO: use TPM PCR properties public static TpmHash GetPcrResetValue(TpmAlgId hashAlg, int pcrNum) { return(pcrNum >= 17 && pcrNum <= 22 ? TpmHash.AllOnesHash(hashAlg) : TpmHash.ZeroHash(hashAlg)); }
/// <summary> /// This sample demonstrates the use of the TPM Platform Configuration /// Registers (PCR). TSS.Net provides several features to model PCR /// semantics. /// </summary> /// <param name="tpm">Reference to the TPM object.</param> static void Pcrs(Tpm2 tpm) { Console.WriteLine("\nPCR sample started."); // // Read the value of the SHA1 PCR 1 and 2 // var valuesToRead = new PcrSelection[] { new PcrSelection(TpmAlgId.Sha256, new uint[] { 1, 2 }) }; PcrSelection[] valsRead; Tpm2bDigest[] values; tpm.PcrRead(valuesToRead, out valsRead, out values); // // Check that what we read is what we asked for (the TPM does not // guarantee this) // if (valsRead[0] != valuesToRead[0]) { Console.WriteLine("Unexpected PCR-set"); } // // Print out PCR-1 // var pcr1 = new TpmHash(TpmAlgId.Sha256, values[0].buffer); Console.WriteLine("PCR1: " + pcr1); // // Extend (event) PCR[1] in the TPM and in the external library and // see if they match // var dataToExtend = new byte[] { 0, 1, 2, 3, 4 }; // // Note that most PCR must be authorized with "null" authorization // tpm.PcrEvent(TpmHandle.Pcr(1), dataToExtend); // // And read the current value // tpm.PcrRead(valuesToRead, out valsRead, out values); // // Update the "simulated" PCR // pcr1.Event(dataToExtend); // // And see whether the PCR has the value we expect // if (pcr1 != values[0].buffer) { throw new Exception("Event did not work"); } // // Update a resettable PCR // tpm.PcrEvent(TpmHandle.Pcr(16), new byte[] { 1, 2 }); // // And reset it // tpm.PcrReset(TpmHandle.Pcr(16)); // // And check that it is indeed zero // tpm.PcrRead(new PcrSelection[] { new PcrSelection(TpmAlgId.Sha256, new uint[] { 16 }) }, out valsRead, out values); // // Did it reset? // if (TpmHash.ZeroHash(TpmAlgId.Sha256) != values[0].buffer) { throw new Exception("PCR did not reset"); } Console.WriteLine("PCR sample finished."); } // Pcrs