You can freely build on How Computers Use Hardware to Stop Software Piracy and Cracking

What this patent covers

This patent describes a computer architecture designed to protect software by keeping it encrypted while in storage and only decrypting it for execution within a secure hardware environment. The system uses a 'violation recognition' mechanism that monitors where instructions are coming from in memory. If the processor attempts to execute code from an unauthorized memory region, a 'destruction means' triggers to wipe the execution key and register data, effectively killing the process before a cracker can analyze it. It also includes a 'handshake' mechanism that allows legitimate jumps between authorized code segments while still preventing unauthorized access to the protected memory regions.

What is now free to use

All 1 claims of US 4558176 are in the public domain. Specifically:

The 1 dependent claim add narrowing limitations and are also free.

What is NOT covered

Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.

• Does not cover software-only copy protection schemes that lack the specific hardware-based destruction and translation mechanisms.

• Does not cover general-purpose encryption methods that do not involve the hardware-level monitoring of memory regions for instruction execution.

• Does not cover modern cloud-based license verification systems that rely on external servers rather than internal hardware state destruction.

Who is building on this today

Major semiconductor companies like Intel and ARM have integrated similar concepts into their silicon, specifically through technologies like Intel SGX and ARM TrustZone. These modern implementations build on the idea of isolating sensitive code and data from the rest of the system at the hardware level.

Products built on expired version of this technology

How to cite this patent in your documentation

Individual. US Patent 4558176. Computer systems to inhibit unauthorized copying, unauthorized usage, and automated cracking of protected software. Granted 1985, expired 2002. Now in the public domain.

Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.

PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.