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Security Fundamentals & Crypto · Intermediate

Split Knowledge

Dividing a secret, such as a cryptographic key, so that no single person knows the whole value.

Definition

Split knowledge ensures a secret can only be reconstructed when multiple custodians combine their portions. It is commonly used for master keys and recovery keys, often implemented with key components or secret-sharing schemes. It is usually combined with dual control.

Example

A master key is split into three components held by three officers, all needed to load it into an HSM.

Exam tip

Watch for 'M of N control' as a related term where any M of N custodians can reconstruct the key.

Related terms