US Patent 10565382 Maintaining keys for trusted boot code

Methods and apparatus are disclosed for securing executable code for execution with a processor using a trusted platform module (TPM). In one example of the disclosed technology, a method of decrypting executable code for execution includes measuring values stored in a CPU boot ROM and measuring second values for executable code stored in non-volatile memory, storing the resulting measurement value in a TPM platform configuration register. The PCR value is used to unseal a key stored in non-volatile memory of the TPM, which key is used to decrypt executable code for execution. Security can be further enhanced by destroying the values stored in the PCR by performing additional measurement operations with the TPM PCR used to generate the measurement value.