Envelop is a flexible cross-chain tool set able to give any NFT new functionality (economic set-up, on-chain royalties, rental mechanism, time/value/event-locks), protection of devaluation and anti-fraud system. Envelop consists of: 1) Protocol to add the digital assets inside NFTs and set-up new features; 2) Oracle to score the collateral and assess the quality of assets; 3) Index to hedge