Security, Privacy, Identity, and Permissioning
What this domain tests
Security architecture, privacy techniques, identity models, and permissioning layers. Expect questions on key management, MSP, private data, zero-knowledge proofs, and GDPR tension.
Core rules
- Permissioning exists at network, channel, chaincode, and data levels. Encryption is not permissioning; access control must be enforced at each layer.
- Fabric MSP maps X.509 certificates to organizations and roles; CAs issue and revoke identities. Losing an admin key can be worse than losing a user key.
- Privacy options: channels, private data collections with hash on-chain and payload off-chain, salting and hashing, zero-knowledge proofs, and selective disclosure.
- On-chain personal data conflicts with erasure rights. Store a hash or pointer, keep the data in a controlled store, and design deletion at the off-chain layer.
- Smart-contract security needs review, testing, least privilege, timelocks, and upgrade controls.
Worked example
A hospital consortium writes a consent proof on-chain and keeps the consent document in an encrypted off-chain store. The chaincode stores H(salt||document ID) and a pointer. Auditors verify the proof; unauthorised peers see only the hash. If the patient revokes consent, the off-chain record is deleted or flagged and the on-chain status changes. The reasoning: the ledger proves integrity and state transition without exposing the record.
Traps
Do not call hashing encryption. Do not put PII on a shared ledger and promise to delete it later. Do not treat TLS as transaction authorization. Do not confuse Fabric CA with MSP - the CA issues credentials, MSP defines membership rules.