Does open source improve system security?

By guarding their source code, most soft-ware producers make it hard for an outsider to help improve system security. But because attackers can also e xamine public source code to find flaws, is source code access a net gain o r loss for security? The question goes beyond technical issues: publishing source code reveals intellectual property and therefore affects the produce r's business model. This article considers this question from several persp ectives and tentatively concludes that making source code available should, on balance, work in favor of system security.