CON.1 Crypto Concept

Appropriate cryptographic methods MUST be selected. In so doing, it MUST be ensured that established algorithms are used that have been examined intensively by experts and do not have any known vulnerabilities. The key lengths recommended at the time MUST also be used.

In backups, cryptographic keys MUST be stored and kept by the IT Operation Department in such a way that unauthorised persons cannot access them. Long-term cryptographic keys MUST be stored outside of the IT systems used.

For long-term storage of encrypted data, checks SHOULD be performed at regular intervals to determine whether the cryptographic algorithms and key lengths used still reflect the state of the art. The IT Operation Department MUST guarantee that data stored in encrypted form can still be accessed after longer periods. The crypto products used SHOULD be archived. The configuration data of crypto products SHOULD be backed up.

It SHOULD be determined whether communication links can be encrypted in a feasible manner with a reasonable amount of resources. If this is the case, communication links SHOULD be encrypted appropriately.

Cryptographic keys SHOULD always be created with appropriate key generators in a secure environment. If possible, cryptographic keys SHOULD be used for one purpose only. In particular, different keys SHOULD be used for encryption and signature creation. The exchange of cryptographic keys SHOULD be carried out using a method that is considered secure.

If keys are used, the authenticity of the origin and integrity of the key data SHOULD be checked.

All cryptographic keys SHOULD be changed at a sufficient frequency. There SHOULD be a defined procedure for scenarios in which a key has been revealed. All created cryptographic keys SHOULD be stored and managed securely.

Keys and certificates that are no longer needed SHOULD be deleted and destroyed securely.

The business processes or specialised procedures that require cryptographic methods SHOULD be defined. The applications, IT systems, and communication links necessary to fulfil the tasks at hand SHOULD then be identified. The IT Operation Department SHOULD use suitable cryptographic mechanisms to secure these elements.

Based on its general security policy, an organisation SHOULD draw up a specific policy for the use of crypto products. In this security policy, the person responsible for the secure operation of cryptographic products SHOULD be specified. There SHOULD be deputising rules in connection with the crypto products used.

Necessary training and awareness safeguards SHOULD be defined for users, along with codes of conduct and reporting channels for potential problems or security incidents. Furthermore, the policy SHOULD define the methods used to ensure that crypto modules are configured securely, used properly, and maintained at regular intervals.

The policy SHOULD be known to all the relevant employees and SHOULD be integral to their work. If the policy is changed or deviations prove necessary, this SHOULD be coordinated with the CISO and documented accordingly. There SHOULD be regular checks on whether the policy is still being properly implemented. The results SHOULD be appropriately documented.

Before a decision can be taken on which cryptographic methods and products will be used in the event of high protection requirements, the following influencing factors SHOULD be determined, among other considerations:

• security aspects (see CON.1.A6 Identifying the Need for Cryptographic Methods and Products)
• technical aspects
• personnel and organisational aspects
• economic aspects
• the lifecycles of cryptographic methods and the key lengths used
• approval of cryptographic products
• legal framework conditions

Before selecting a cryptographic product, an organisation SHOULD define the requirements to be met by the product. Here, aspects such as the scope of functions, interoperability, efficiency, and protection against incorrect operation and malfunction SHOULD be considered. It SHOULD be checked whether certified products should be given priority. The selection process SHOULD also consider the future deployment locations due to the export and import restrictions on cryptographic products, for example.

As a general rule, products that do not make it possible to control the storage of keys SHOULD NOT be used.

A crypto concept SHOULD be developed that is integrated into the security concept of the organisation in question. The concept SHOULD describe all the technical and organisational specifications for the cryptographic products used. Additionally, all the relevant applications, IT systems, and communication links SHOULD be listed. The created crypto concept SHOULD be updated at regular intervals.

Crypto modules SHOULD be installed and configured securely. All preset keys SHOULD be changed. Afterwards, whether the crypto modules work properly and can actually be operated by users SHOULD be tested.

Furthermore, the requirements for the operational environment SHOULD be defined. If an IT system is changed, whether the cryptographic methods used are still effective SHOULD be tested. The configuration of the crypto modules SHOULD be documented and checked at regular intervals.

User roles SHOULD be defined when configuring a crypto module. Access control and authentication mechanisms SHOULD be used in order to verify whether an employee is actually allowed to use the desired service. The crypto module SHOULD be configured such that the authentication information has to be re-entered every time there is a role change or a specified period of inactivity as passed.

The interaction between the operating system and the crypto modules SHOULD ensure the following:

• the crypto modules installed cannot be disabled or circumvented without this being noticed.
• the applied or stored keys cannot be compromised.
• the data to be protected can only be stored on storage media without encryption or leave the information-processing system with the knowledge of and under the control of the user
• attempted manipulations of the crypto module will be detected.

There SHOULD be training for users and administrators on handling the relevant crypto modules. The meaning of the security settings of crypto modules and why they are important SHOULD be explained in detail to the users. Furthermore, they SHOULD be made aware of the threats that result from bypassing or disabling these security settings for the sake of convenience. The training content SHOULD always be adapted to the particular operational scenarios at hand.

Administrators SHOULD also receive specific training on the administration of crypto modules. They SHOULD also be provided with an overview of basic cryptographic terms.

A process SHOULD be established that can be used in the event of a weakened cryptographic method. In so doing, it SHOULD be ensured that the weakened cryptographic method can be secured or will be replaced with an appropriate alternative.

The IT Operation Department SHOULD ensure that unauthorised physical access to the contents of a crypto module is prevented. Hardware and software products used as crypto modules SHOULD be able to perform a self-test.

Whether additional safeguards are necessary for emission security SHOULD be examined. In particular, this SHOULD be ensured when processing government material that is classified as VS-VERTRAULICH (VS-CONFIDENTIAL) or higher.

Replacement crypto modules SHOULD be kept available.