1. A method implemented at least in part by a device, the method comprising: generating a checksum value for a segment of a digital good based at least in part on both a set of inputs to the segment and the content of a register that results from applying the set of inputs to the segment and modification of the content of the register by instructions in the segment; comparing the generated checksum value to a stored checksum value corresponding to the segment; and determining that the digital good has been tampered with if the generated checksum value does not match the stored checksum value.