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ICCO - Initial Cross-Chain Offerings

Objective

To use the Wormhole message passing protocol to enable trustless cross-chain token sales.

Background

Token sales are one of the major applications of today's blockchains. Currently they are either conducted on a single chain in a trustless fashion or in a centralized fashion with support to contribute tokens from multiple chains. Using wormhole we can bridge this gap - Allow users to contribute assets on all supported chains and issue a token that we can bridge to all chains for them to claim after the sale has been concluded.

Goals

We want to implement a generalized, trustless cross-chain mechanism for token sales.

  • Allow contributions of whitelisted assets on all supported chains
    • Users don't need to maintain multiple wallets, but can conveniently participate from their native environment.
  • Issue a token on wormhole chain and leverage the wormhole token bridge to distribute them to all participants on their chains.

Non-Goals

  • Automatically relay messages across chains. The design assumes there is always a party interested in synchronizing the data across chains, let it be the token issuer or an investor who wants to claim its tokens.

Overview

There are two programs needed to model this.

  • A TokenSaleConductor, which lives on one chain (It can exist on all chains, however it only needs to be invoked on one to initiate a sale).
    • It holds the tokens that are up for sale and maintains and collects the state around the sale.
  • TokenSaleContributor contracts live on all chains.
    • Collects contributions, distributes tokens to contributors after the sale has ended and the token allocation has been bridged.

Detailed Design

To create a sale, a user invokes the createSale() method on the sale conductor. It takes the following set or arguments:

  • A Raise struct with the following arguments:
    • Offered token native address
    • Offered token native chain
    • Offered token amount
    • A start time for when contributions can be accepted
    • An end time for when contributions will no loner be accepted
    • A minimum USD amount to raise
    • A maximum USD amount to raise
    • The address that can claim the proceeds of the sale
    • The address that should receive the offered tokens in case the minimum raise amount is not met
    • The ATA on the Solana contributor where offered tokens will be sent
  • An array of accepted tokens on each chain + the USD conversion rate which they are accepted at

The createSale() method deposits the offered tokens, assigns an ID which identifies the sale and attests a SaleInit packet over the wormhole. This packet contains all the information from above. The sale information is also stored locally.

The attested SaleInit packet is submitted to the TokenSaleContributor contracts. The contributor contracts stores the sale information locally which is relevant to its chain.

The TokenSaleConductor contract can terminate the sale by calling abortSaleBeforeStartTime() before the sale period begins. Only the wallet that called createSale() can invoke this method.

During the start and end timestamp the TokenSaleContributor contracts accept contributions in the specified tokens. The contribute() method takes an argument bytes memory sig which is a third party signature stating that KYC was performed for a particular contribution. The TokenSaleContributor calls verifySignature to recover a public key from the passed signature. If the public key matches the authority address in the TokenSaleContributor state, the contribution is permitted.

After the sale duration anyone can call the attestContributions() method on the contributor, which attests a Contribution packet over the wormhole.

The TokenSaleConductor now collects the Contributions packets from all chains & tokens.

After all contributions have been collected, anyone can call the sealSale() method on the Conductor. The method evaluates whether the minimum raise amount has been met using the conversion rates specified initially (a later version could use rates from an oracle at closing). In case it was successful it:

  • Calculates allocations and excess contributions (if total contributions sum to a value larger than the maximum raise amount)
    • Excess contributions are calculated by taking the difference between the maximum raise amount and the total contributions. Each contributor receives excess contributions proportional to their contribution amount (individualContribution / totalContributions * totalExcessContributions)
  • Emits a SaleSealed packet - indicated to the Contributor contracts that the sale was successful
  • Bridges the relevant share of offered tokens to the Contributor contracts

Or in case the goal was not met, it:

  • Emits a SaleAborted packet.
  • Allows a permissionless method claimRefund to be called for the refundRecipient

The Contributor contracts has two functions to consume the relevant attestations:

  • saleSealed()
    • Starts to accept claims of users acquired tokens via claimAllocation()
      • Also pays out excess contributions
    • Bridges the raised funds over to the recipient
  • saleAborted()
    • Starts to accept refund claims via claimRefund()

API / database schema

TokenSaleConductor:

  • createSale(ICCOStructs.Raise memory raise, ICCOStructs.Token[] acceptedTokens)
  • collectContributions(vaa Contributions)
  • abortSaleBeforeStartTime(uint saleId)
  • sealSale(uint saleId)
  • claimRefund(uint saleId)
  • saleExists(uint saleId)

Owner Only:

  • registerChain(uint16 contributorChainId, bytes32 contributorAddress)
  • upgrade(uint16 conductorChainId, address newImplementation)
  • updateConsistencyLevel(uint16 conductorChainId, uint8 newConsistencyLevel)
  • transferOwnership(uint16 conductorChainId, address newOwner)

TokenSaleContributor:

  • initSale(vaa SaleInit)
  • verifySignature(bytes memory encodedHashData, bytes memory sig)
  • contribute(uint saleId, uint tokenIndex, uint amount, bytes memory sig)
  • attestContributions(uint saleId)
  • saleSealed(vaa SaleSealed)
  • saleAborted(vaa SaleAborted)
  • claimAllocation(uint saleId, uint tokenIndex)
  • claimRefund(uint saleId, uint tokenIndex)
  • saleExists(uint saleId)

Owner Only:

  • upgrade(uint16 contributorChainId, address newImplementation)
  • updateConsistencyLevel(uint16 contributorChainId, uint8 newConsistencyLevel)
  • updateAuthority(uint16 contributorChainId, address newAuthority)
  • transferOwnership(uint16 contributorChainId, address newOwner)

Structs:

  • Token

    • uint16 chainId
    • bytes32 address
    • uint256 conversionRate

  • Contribution

    • uint8 tokenIndex (index in accepted tokens array)
    • uint256 contributedAmount

  • Allocation

    • uint8 tokenIndex (index in accepted tokens array)
    • uint256 allocation (amount distributed to contributors on this chain)
    • uint256 excessContribution (excess contributions refunded to contributors on this chain)

  • Raise

    • bytes32 token (sale token native address)
    • uint16 tokenChain (sale token native chainId)
    • uint256 tokenAmount (token amount being sold)
    • uint256 minRaise (min raise amount)
    • uint256 maxRaise (max raise amount)
    • uint256 saleStart (timestamp raise start)
    • uint256 saleEnd (timestamp raise end)
    • address recipient (recipient of sale proceeds)
    • address refundRecipient (refund recipient in case the sale is aborted)
    • bytes32 solanaTokenAccount (sale token ATA for Solana)

Payloads:

SaleInit:

// PayloadID uint8 = 1
uint8 payloadID;
// Sale ID
uint256 saleID;
// Address of the token being sold. Left-zero-padded if shorter than 32 bytes
bytes32 tokenAddress;
// Chain ID of the token being sold
uint16 tokenChain;
// sale token decimals
uint8 tokenDecimals
// token amount being sold
uint256 tokenAmount;
// min raise amount
uint256 minRaise;
// max raise amount;
uint256 maxRaise;
// timestamp raise start
uint256 saleStart;
// timestamp raise end
uint256 saleEnd;
// accepted tokens length
uint8 tokensLen;

// repeated for tokensLen times, Struct 'Token'
  // Address of the token. Left-zero-padded if shorter than 32 bytes
  bytes32 tokenAddress;
  // Chain ID of the token
  uint16 tokenChain;
  // conversion rate for the token
  uint256 conversionRate;

// sale token ATA for Solana
bytes32 solanaTokenAccount
// recipient of proceeds
bytes32 recipient;
// refund recipient in case the sale is aborted
bytes32 refundRecipient;

ContributionsSealed:

// PayloadID uint8 = 2
uint8 payloadID;
// Sale ID
uint256 saleID;
// Chain ID
uint16 chainID;

// local contributions length
uint8 contributionsLen;

// repeated for tokensLen times, Struct 'Contribution'
  // index in acceptedTokens array
  uint8 index
  // contributed amount of token
  uint256 contributed;

SaleSealed:

// PayloadID uint8 = 3
uint8 payloadID;
// Sale ID
uint256 saleID;

// local allocations length
uint8 allocationsLen;

// repeated for allocationsLen times, Struct 'Allocation'
  // index in acceptedTokens array
  uint8 index
  // amount of sold tokens allocated to contributors on this chain
  uint256 allocation;
  // excess contributions refunded to contributors on this chain
  uint256 excessContribution;

SaleAborted:

// PayloadID uint8 = 4
uint8 payloadID;
// Sale ID
uint256 saleID;