A software development system (SDS) (228) digitally signs software (230) developed on the system. The SDS (228) executes on a computer system (112) having a trusted computing platform. The platform includes protected areas (220, 226) that store data and cannot be accessed by unauthorized modules. A code signing module (232) executing in a protected area (226) obtains a private/public key pair and a corresponding digital certificate. The SDS (228) is configured to automatically and transparently utilize the code signing module (232) to sign software (230) produced by the system. End-user systems (114) receive the certificate with the software and can use it to verify the signature. This verification will fail if a parasitic virus or other malicious code has altered the software (230). Accordingly, the SDS (228) greatly reduces the risk of malicious code executing on the end-user computer system (114).