Software
Software is also said to be tamper-resistant when it contains measures to make reverse engineering harder, or to prevent a user from modifying it against the manufacturer's wishes (removing a restriction on how it can be used, for example). One commonly used method is code obfuscation.
However, effective tamper resistance in software is much harder than in hardware, as the software environment can be manipulated to near-arbitrary extent by the use of emulation. Commercial application hardening solutions, such as those sold by Arxan Technologies or Metaforic, are typically more cost effective and secure than building an in-house tamper resistance solution.
If implemented, trusted computing would make software tampering of protected programs at least as difficult as hardware tampering, as the user would have to hack the trust chip to give false certifications in order to bypass remote attestation and sealed storage. However, the current specification makes it clear that the chip is not expected to be tamper-proof against any reasonably sophisticated physical attack; that is, it is not intended to be as secure as a tamper-resistant device.
A side effect of this is that software maintenance gets more complex, because software updates need to be validated and errors in the upgrade process may lead to a false-positive triggering of the protection mechanism.
Read more about this topic: Tamper Resistance