TIP-2 Decentralized Certificates (DeCert) is a standard for decentralized certificate storage in the Free TON blockchain.
This standard is used in providing services that require a certified provable key-value store. For example, a Decentralized Name Service (DeNS) or a Proof of Ownership / Proof of Purchase certificate.
Architecturally, TIP-2 is similar to TIP-3 and is based on the interaction between the root smart contract and the user.