ISO 27002:2022, Control 8.24 – Use of Cryptography

Ownership on Control 8.24

Compliance with 8.24 requires the establishment and implementation of a specific policy on cryptography, creating an effective key management process, and determining the type of cryptographic technique appropriate to the level of information classification assigned to a particular information asset.

Therefore, the chief information security officer should be responsible for setting out appropriate rules and procedures for the use of cryptographic keys.

General Guidance on Compliance

Control 8.24 lists seven requirements that organisations should adhere to when using cryptographic techniques:

1. Organisations should create and maintain a topic-specific policy on the use of cryptography. This policy is essential for maximising the benefits of cryptographic techniques and it reduces the risks that may arise from the use of cryptography. It is also noted that this policy should cover general principles governing the protection of information.
2. Organisations should consider the level of sensitivity of the information assets and the information classification level assigned to them when they decide on the type, strength, and quality of the encryption algorithm.
3. Organisations should implement cryptographic techniques when information is transferred to mobile devices or to storage media equipment or when information is stored on these devices.
4. Organisations should address issues related to key management, including the creation and protection of cryptographic keys and the recovery plan for encrypted data in the event that keys are lost or compromised.
5. Organisations should set out the roles and responsibilities for the following:
• Establishment and implementation of the rules on how the cryptographic techniques will be used.
• How keys will be handled, including how they will be generated.
6. The adoption and approval of standards across the organisation for the cryptographic algorithms, cipher strength, and usage practices for cryptography.
7. Organisation should address how encrypted information may interfere with the controls that entail the content inspection such as malware detection.

Furthermore, Control 8.24 highlights that organisations should take into account laws and requirements that may restrict the use of cryptography, including the cross-border transfer of encrypted information.

Finally, organisations are also advised to address liability and continuity of services when they enter into service agreements with third parties for the provision of cryptographic services.

Supplementary Guidance on Key Management

Organisations should define and apply secure procedures for the creation, storage, retrieval, and destruction of cryptographic keys.

In particular, organisations should put in place a robust key management system that includes rules, processes, and standards for the following:

• Generation of cryptographic keys for different systems and applications.
• Issuance and acquisition of public-key certificates.
• Distribution of keys to intended recipients, including the process of key activation.
• Storage of keys and how authorised parties can access to keys.
• Changing of keys.
• Handling of compromised keys.
• Revocation of keys for why they are compromised or when authorised persons leave an organisation.
• Recovery of lost keys.
• Key back-up and archival.
• Destroying keys.
• Keeping a log of all activities related to each key.
• Determining activation and deactivation dates for keys.
• Responding to legal requests for having access to keys.

Last but not the least, this supplementary guidance cautions organisations against three particular risks:

• Secret and protected keys should be protected against unauthorised use.
• Equipment used to create or store encryption keys should be protected via physical security measures.
• Organisations should maintain the authenticity of public keys.

What Are the Benefits of Cryptography?

After highlighting that organisations can ensure the authenticity of public keys by methods such as public key management processes, Control 8.24 explains how cryptography can help organisations achieve four information security objectives:

1. Confidentiality: Cryptography protects and maintains the confidentiality of data both in transit and at rest.
2. Integrity and authenticity: Digital signatures and authentication codes can ensure the authenticity and integrity of information communicated.
3. Non-repudiation: Cryptographic methods provide evidence of all events or actions performed such as receipt of information.
4. Authentication: Cryptographic methods enable organisations to verify the identity of users requesting access to systems and applications.

Changes and Differences from ISO 27002:2013

27002:2022/8.24 replace 27002:2013/(10.1.1. And 10.1.2)

While the content of both versions is almost identical, there are a few structural changes.

Whereas the 2013 version addressed the use of cryptography under two separate controls, namely 10.1.1. And 10.1.2, the 2022 version combined these two under one Control, 8.24.

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