The Verilog 2005 standard introduced a new feature to support protected intellectual property. This feature allows IP vendors to deliver models in encrypted form. Vendors may choose to encrypt entire files, or only encrypt parts of a model. You can choose to encrypt entire files, or only encrypt parts of a model. Xilinx has begun using this method to encrypt it’s latest IP models, since the resulting models simulate faster than object-code model equivalents (e.g. SmartModels).
The simplest way to encrypt your source code is to use VeriLogger’s public key. This will allow any VeriLogger user to compile and use the encrypted model by simply adding the file to their project. VeriLogger will compile and simulate using the encrypted code, but the user will not have access to any of the source code. You can also encrypt a file with a public key of own, then provide this key to consumers of your IP so that they can use the IP with any simulator that supports the encryption standard.
Before encrypting your source, test the unencrypted source code with VeriLogger Extreme to ensure that it compiles without errors. Since the end-user of your IP will not have access to the source code, they will be unable to fix any problems, and error messages in encrypted sections of code will be useless.
To create an encrypted file, perform the steps below:
1. Add `pragma protect directives to the source to delimit which sections to encrypt. Anything between a `pragma protect begin line and a `pragma protect end will be encrypted. Anything outside these directives will be copied verbatim to the output file.
2. Run the simulation generator, simxgen, to encrypt a source file called sram.v:
simx +protect sram.v
This will generate an encrypted file called sram.vp. The .vp file extension indicates an encrypted verilog file.
For details on how to create and use your own encryption keys or how to encrypt a model with multiple keys, see the section on Verilog Protected Envelopes in the Verilogger online help.