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Vier-Augen-Prinzip
Mistakes happen, and sometimes so does intent. The four-eyes principle ensures that important decisions do not depend on a single person. In information security, it is one of the simplest and most effective controls – even when data carriers are erased, destroyed or written off from inventory.
In brief
The four-eyes principle is a control rule under which an important action is only valid if a second, independent person checks or approves it. This way, errors are discovered earlier and misuse is made harder, because nobody can act alone. In IT retirement, the four-eyes principle is suitable, for example, for approving devices for erasure, handing over to service providers and reconciling the proofs.
What is the four-eyes principle?
With the four-eyes principle, also written 4-eyes principle, two people are involved in an action. One carries it out, the other checks or approves it. Both document this, for example with a signature or digital approval. The principle is well known from payment transactions: a transfer above a certain amount needs a second approval.
The principle is closely related to segregation of duties. There, incompatible tasks are permanently assigned to different people, such as ordering and paying. ISO/IEC 27001 lists segregation of duties as a separate control in Annex A. In banking, the BaFin's MaRisk require clear segregation of duties.
Where the four-eyes principle is used
| Area | Typical application |
|---|---|
| Finance | Approval of payments, postings and contracts |
| Permissions | Granting of administrator rights only after approval |
| IT operations | Changes to production systems (change management) |
| Data protection | Approval of erasures and data exports |
| IT retirement | Approval of the device list, handover to service providers, reconciliation of erasure and destruction proofs |
Four-eyes principle in IT retirement
In retirement, three moments are particularly delicate. First, the selection: which devices may be erased, and do they still hold data that must be retained? Second, the handover: do the number and serial numbers in the acceptance record match the device list? Third, the conclusion: is there proof for every device?
If two people are involved in each of these, gaps are noticed faster. This strengthens the Chain of custody and is a building block of your technical and organizational measures (TOM). The principle is complemented by the Need-to-know principle: only those who really have to work on the devices are given access.
How to evaluate service providers for these steps is shown by the guide Choosing an ITAD provider.
Rule of thumb: The four-eyes principle does not replace trust, it makes it verifiable.
Controls at Second IT
At Second IT, the processing areas are protected by access control and video surveillance. Only authorized employees have access. Every device is registered by serial number at goods receipt, every erasure with Blancco is documented and backed by a digitally signed erasure certificate. More on Data security at Second IT.
Frequently asked questions about the four-eyes principle
Is the four-eyes principle required by law?
Not in general. In regulated sectors such as banks or insurers, however, supervisory requirements call for segregation of duties and controls. Standards such as ISO/IEC 27001 and the GDPR obligation to take appropriate organizational measures also speak in favor of the principle.
What is the difference between the four-eyes principle and segregation of duties?
With the four-eyes principle, a second person checks a single action. With segregation of duties, incompatible tasks are permanently assigned to different people. The two complement each other.
How do I document the four-eyes principle?
Most simply with two signatures or two digital approvals, each with a date. In IT retirement, the device list, the acceptance record and the final check of the proofs are suitable for this.
Who can be the second person in the four-eyes principle?
A person who checks independently of the person carrying out the action and can assess professionally what they are approving. They should not have carried out the action themselves. Both parties document the check, for example with a signature or digital approval.
Why should the handover of old devices follow the four-eyes principle?
Two people reconcile the number and serial numbers in the acceptance record with the device list. This way, gaps are noticed immediately, before the devices leave the building. This strengthens the chain of custody and is a building block of your technical and organizational measures.
Controlled processes from pickup to the erasure certificate.
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