Key Escrow

---

Key escrow refers to the secure storage and management of cryptographic keys by a trusted third party, known as an escrow agent.

• ensures encrypted data remains accessible under specific circumstances
  • e.g. legal obligations, instances of key compromise, or secure key recovery
• If a private or secret key is lost or damaged,
  • ciphertexts cannot be recovered unless a backup of the key has been made
• Making copies of the key is problematic
  • becomes more likely that a copy will be compromised
  • more difficult to detect that a compromise has occurred
• mitigated by escrow and M of N controls
  • Escrow is the storage of a backup key with a third party.
    • in general terms, means that something is held independently
  • M of N means that an operation cannot be performed by a single individual.
    • a quorum (M) of available persons (N) must agree to authorize the operation
• key can be split into parts
  • Each part can be held by separate escrow providers
    • reducing the risk of compromise
• key recovery agent (KRA) is an account with permission to access a key held in escrow
  • recovery policy can require two or more KRAs to authorize the operation
    • mitigates the risk of a KRA attempting to impersonate the key owner