Encryption

Last updated Dec 6, 2025

Author: Stuart Barker | ISO 27001 Lead Auditor

What is Encryption?

ISO 27001 Encryption is a way of scrambling information so that it can’t be read by just anyone. Think of it like a secret code. You use a key to lock the information, and only someone with the right key can unlock it to see the original message.

Examples

  • Sending a private message to a friend online. The app uses encryption to make sure only your friend can read it.
  • Protecting your credit card details when you shop on a website. The website uses encryption to keep your information safe.

Context

In the world of ISO 27001, which is about keeping information safe, encryption is a key tool. It helps companies protect their important information, like customer details or business secrets, from being seen by people who shouldn’t see it. It’s a way of making sure that even if someone gets the information, they can’t understand it.

Relevant ISO 27001 Controls

The following controls from the ISO/IEC 27001:2022 standard are related to encryption:

ISO 27001:2022 requirements

ISO 27001 Clauses

ISO 27001 Clause 4.1 – Understanding The Organisation And Its Context

ISO 27001 Clause 4.2 – Understanding The Needs And Expectations of Interested Parties

ISO 27001 Clause 4.3 – Determining The Scope Of The Information Security Management System

ISO 27001 Clause 4.4 – Information Security Management System

ISO 27001 Clause 5.1 – Leadership and Commitment

ISO 27001 Clause 5.3 – Organisational Roles, Responsibilities and Authorities

ISO 27001 Clause 6.1.1 – Planning General

ISO 27001 Clause 6.1.2 – Information Security Risk Assessment

ISO 27001 Clause 6.1.3 – Information Security Risk Treatment

ISO 27001 Clause 6.2 – Information Security Objectives and Planning to Achieve Them

ISO 27001 Clause 6.3 – Planning Of Changes

ISO 27001 Clause 7.1 – Resources

ISO 27001 Clause 7.2 – Competence

ISO 27001 Clause 7.3 – Awareness

ISO 27001 Clause 7.4 – Communication

ISO 27001 Clause 7.5.1 – Documented Information

ISO 27001 Clause 7.5.2 – Creating and Updating Documented Information

ISO 27001 Clause 8.3 – Information Security Risk Treatment

ISO 27001 Clause 9.1 – Monitoring, Measurement, Analysis, Evaluation

ISO 27001 Clause 9.2 – Internal Audit

ISO 27001 Clause 9.3 – Management Review

ISO 27001 Clause 10.1 – Continual Improvement

ISO 27001 Clause 10.2 – Nonconformity and Corrective Action

ISO 27001 Organisation Controls

ISO 27001 Annex A 5.1: Policies for information security

ISO 27001 Annex A 5.2: Information Security Roles and Responsibilities

ISO 27001 Annex A 5.3: Segregation of duties

ISO 27001 Annex A 5.4: Management responsibilities

ISO 27001 Annex A 5.5: Contact with authorities

ISO 27001 Annex A 5.6: Contact with special interest groups

ISO 27001 Annex A 5.7: Threat intelligence

ISO 27001 Annex A 5.8: Information security in project management

ISO 27001 Annex A 5.9: Inventory of information and other associated assets

ISO 27001 Annex A 5.10: Acceptable use of information and other associated assets

ISO 27001 Annex A 5.11: Return of assets

ISO 27001 Annex A 5.12: Classification of information

ISO 27001 Annex A 5.13: Labelling of information

ISO 27001 Annex A 5.14: Information transfer

ISO 27001 Annex A 5.15: Access control

ISO 27001 Annex A 5.16: Identity management

ISO 27001 Annex A 5.17: Authentication information

ISO 27001 Annex A 5.18: Access rights

ISO 27001 Annex A 5.19: Information security in supplier relationships

ISO 27001 Annex A 5.20: Addressing information security within supplier agreements

ISO 27001 Annex A 5.21: Managing information security in the ICT supply chain

ISO 27001 Annex A 5.22: Monitoring, review and change management of supplier services

ISO 27001 Annex A 5.23: Information security for use of cloud services

ISO 27001 Annex A 5.24: Information security incident management planning and preparation

ISO 27001 Annex A 5.25: Assessment and decision on information security events

ISO 27001 Annex A 5.26: Response to information security incidents

ISO 27001 Annex A 5.27: Learning from information security incidents

ISO 27001 Annex A 5.28: Collection of evidence

ISO 27001 Annex A 5.29: Information security during disruption

ISO 27001 Annex A 5.30: ICT readiness for business continuity

ISO 27001 Annex A 5.31: Identification of legal, statutory, regulatory and contractual requirements

ISO 27001 Annex A 5.32: Intellectual property rights

ISO 27001 Annex A 5.33: Protection of records

ISO 27001 Annex A 5.34: Privacy and protection of PII

ISO 27001 Annex A 5.35: Independent review of information security

ISO 27001 Annex A 5.36: Compliance with policies and standards for information security

ISO 27001 Annex A 5.37: Documented operating procedures

ISO 27001 Technical Controls

ISO 27001 Annex A 8.1: User Endpoint Devices

ISO 27001 Annex A 8.2: Privileged Access Rights

ISO 27001 Annex A 8.3: Information Access Restriction

ISO 27001 Annex A 8.4: Access To Source Code

ISO 27001 Annex A 8.5: Secure Authentication

ISO 27001 Annex A 8.6: Capacity Management

ISO 27001 Annex A 8.7: Protection Against Malware

ISO 27001 Annex A 8.8: Management of Technical Vulnerabilities

ISO 27001 Annex A 8.9: Configuration Management 

ISO 27001 Annex A 8.10: Information Deletion

ISO 27001 Annex A 8.11: Data Masking

ISO 27001 Annex A 8.12: Data Leakage Prevention

ISO 27001 Annex A 8.13: Information Backup

ISO 27001 Annex A 8.14: Redundancy of Information Processing Facilities

ISO 27001 Annex A 8.15: Logging

ISO 27001 Annex A 8.16: Monitoring Activities

ISO 27001 Annex A 8.17: Clock Synchronisation

ISO 27001 Annex A 8.18: Use of Privileged Utility Programs

ISO 27001 Annex A 8.19: Installation of Software on Operational Systems

ISO 27001 Annex A 8.20: Network Security

ISO 27001 Annex A 8.21: Security of Network Services

ISO 27001 Annex A 8.22: Segregation of Networks

ISO 27001 Annex A 8.23: Web Filtering

ISO 27001 Annex A 8.24: Use of Cryptography

ISO 27001 Annex A 8.25: Secure Development Life Cycle

ISO 27001 Annex A 8.26: Application Security Requirements

ISO 27001 Annex A 8.27: Secure Systems Architecture and Engineering Principles

ISO 27001 Annex A 8.28: Secure Coding

ISO 27001 Annex A 8.29: Security Testing in Development and Acceptance

ISO 27001 Annex A 8.30: Outsourced Development

ISO 27001 Annex A 8.31: Separation of Development, Test and Production Environments

ISO 27001 Annex A 8.32: Change Management

ISO 27001 Annex A 8.33: Test Information

ISO 27001 Annex A 8.34: Protection of information systems during audit testing