yavs, an early simulator for Very High Speed Integrated Circuit Hardware Description Language (VHDL), used to read an encrypted vendor model as if its encoded payload were hardware source. One protected file could produce thousands of lexer warnings followed by a misleading syntax error. yavs now recognizes the Institute of Electrical and Electronics Engineers (IEEE) 1735 protection envelope and stops at its first line with one error.
The detector accepts both common forms of the protection directive, ignores capitalization, and scans the header for the encryption tool and number of vendor key blocks. The diagnostic points to the line where the envelope begins, then tells the engineer to request an unencrypted simulation model or use a simulator that holds the vendor's key. The parser never attempts to decrypt the intellectual property, and the detector lives in a language-neutral module that a future Verilog front end can reuse.
Compiler diagnostics are part of verification throughput because engineers often meet a tool first through broken input. This change does not add support for protected models, but it turns an apparent design failure into a clear compatibility decision. Other open simulators should test encrypted inputs explicitly, since stopping once with the right next step is much more useful than accepting bytes they cannot interpret.