Learn in the textbookLaws on Unauthorized Access and Cyber Crime
DefinitionThe Unauthorized Access Prohibition Act (不正アクセス禁止法) is a law that forbids entering, over a network and without permission, a computer protected by an access control function (アクセス制御機能), as well as acts that help someone do so.
ExplanationAn access control function (アクセス制御機能) is a mechanism by which the person managing a computer, the access administrator (アクセス管理者), checks users with an identification code (識別符号) such as an ID and password and lets only permitted people in. Besides entering someone else's identification code without permission, getting around the restrictions by exploiting a weakness in the OS or software, known as a security hole (セキュリティホール), also counts as unauthorized access. A 2012 amendment added wrongfully obtaining or storing someone else's identification code, and trying to get people to enter it on a fake screen, to the prohibited acts.
AnalogyIt is like a rule that bans both giving someone else's PIN over the phone to handle their bank account and telling that PIN to a third person without permission.
Memory hookThe core is not "access" but "breaking through a control." A door with no lock (access control) falls outside what this law protects.