CSA Preface Standards development within the Information Technology sector is harmonized with international standards development. Through the CSA Technical Committee on Information Technology (TCIT), Canadians serve as the SCC Mirror Committee (SMC) on ISO/IEC Joint Technical Committee 1 on Information Technology (ISO/IEC JTC1) for the Standards Council of Canada (SCC), the ISO member body for Canada and sponsor of the Canadian National Committee of the IEC. Also, as a member of the International Telecommunication Union (ITU), Canada participates in the International Telegraph and Telephone Consultative Committee (ITU-T). At the time of publication, ISO/IEC 20897-1:2020 is available from ISO and IEC in English only. CSA Group will publish the French version when it becomes available from ISO and IEC. This Standard has been formally approved, without modification, by the Technical Committee and has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group. Scope This document specifies the security requirements for physically unclonable functions (PUFs). Specified security requirements concern the output properties, tamper-resistance and unclonability of a single and a batch of PUFs. Since it depends on the application which security requirements a PUF needs to meet, this documents also describes the typical use cases of a PUF. Amongst PUF use cases, random number generation is out of scope in this document.