Minting ERC721 on-chain has become increasingly expensive as Ethereum and gas prices rose. A traditional ERC721 minting costs today between 100 000 to 200 000 gas per asset. These prices are prohibitively expensive for many use-cases. StarkEx solves this!
Off-chain minting is a StarkEx operation enabling the off-chain creation of assets. It consists of assigning a new
assetId and an
amount that describes the asset to a specific
This asset is created off-chain and does not have yet an on-chain representation. The
assetId is encoded in a compressed form called the Minting Blob which is required in order to withdraw on-chain. The
assetId definition is specified here. Notice that the Minting Blob is not stored on-chain and should be received out of band.
To ensure that StarkEx cannot create any arbitrary
assetId (for instance, minting a large amount of ETH), off-chain minting can only create a mintable
assetId if it respects the following conditions:
The operation does not overwrite an existing
Bit 251 of the
assetId must be 1
Technically, the operation is defined as the change from an empty account to an account containing an
StarkKey, a mintable
assetId and an amount.
Notice that there is no restriction on the operator's ability to remint an asset.
To be fully non-custodial, a mintable asset must be paired with an on-chain contract that the asset will be minted at. At Withdraw, the user is required to call
withdrawAndMint and provide the
mintingBlob for the asset contract to create the token.