StarkEx Deep Dive 🐬
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Full Withdrawal
The function
fullWithdrawalRequest is a part of an anti-censorship mechanism that allows the user to withdraw his funds. The user supplies the vaultId and the starkKey. Only the user to whom this starkKey belongs may submit this request. When this function is called, the event LogFullWithdrawalRequest (with the relevant starkKey, vaultId) is emitted.The Full Withdrawal function consumes a lot of gas and is expected to be used only as an anticensorship mechanism. For regular withdrawals, check out the Withdrawal flow, and the Withdrawal function.
If the application fails to service the request, upon the expiration of a
FREEZE_GRACE_PERIOD, the user is entitled to freeze the contract by calling freezeRequest. (See the entire flow here and the conditions of a valid fullWithdrawal request here). The user supplies the vaultId and the starkKey and indicating the vaultId for which the full withdrawal request has not been serviced. Once the contract is frozen, funds can be extracted using the escape operation, fully described in Escapes.A user cannot cancel Full Withdrawal requests.
To avoid the potential attack of the application by a flood of full withdrawal requests, the rate of such requests must be limited. In the current implementation, this is achieved by making the request's cost exceed 1M gas.
Escape
Once the application becomes frozen (see Forced Operations for the full flow) the escape operation is what allows users to withdraw their funds and leave the application.
Any escaper entity/user may perform an escape operation as follows:
- 1.Escapers must obtain a Merkle path of a vault to be evicted with respect to the frozen vault tree root. Typically, once the application is frozen, such data will be made public or obtainable from an application API, depending on the application's data availability approach.
- 2.Escapers call
verifyEscapefunction on theEscapeVerifiercontract with the Merkle proof for the vault to be evicted. See Escape Verifier for more details on the proof structure. If the proof is valid, this results in the registration of the following fact -keccak256(starkKey, assetId, quantizedAmount, vaultRoot, height, vaultId) - 3.Escapers call
escapefunction with the same parameters as submitted to theEscapeVerifier(starkKey,assetId,quantizedAmount,vaultId). If a proof was accepted for the same parameters by theEscapeVerifier, and no prior escape call was made for the vault, the contract adds the vault balance to an on-chain pending withdrawals account under thestarkKeyof the vault owner and the appropriateassetId. - 4.The owner of the vault may then withdraw this amount from the pending withdrawals account by calling the normal withdraw function (see Withdrawal) to transfer the funds to the user's ETH or ERC20 account (depending on the token type).
Note that while anyone can perform the initial steps of the escape operation (including the application, for example), only the vault owner may perform the final step of transferring the funds.
Last modified 1mo ago
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