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Handshake (Crypto signature)

Handshake is implemented as an Ethereum smart contract written in Solidity. For basic handshakes that involve no payment, we provide the contract BasicHandshake to facilitate an agreement between 2 parties. For a more advanced use-case which involves a payment (currently in ETH), PayableHandshake receives an escrow and locks it for a specified window of time. To protect users' payment, the contract only transfers the payment when both parties agree with each other.

Basic handshake

One party starts by initiating a Handshake. They are given the option to set deadlines, describe an agreement or upload a document if necessary. The second party will receive a notification that the Handshake has been initiated, after which they will be able to respond with their own blockchain-secured signature.

API

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function init(address acceptor, bytes32 offchain) public

Initiate a Handshake with the address of initiator and acceptor (the other party). Offchain refers to the record in the offchain backend database.

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function shake(uint hid, bytes32 offchain) public

This action details the response: Handshaking with the Handshake ID (hid) that initiated the Handshake.

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Payable handshake

This contract allows two parties (payer & payee) to sign off on an agreement that involves payment - typically to do with a product delivered or services rendered. To initiate a Handshake (go to Shake state): the payee proposes a Handshake (init) and the payer agrees to sign off on it (Shake). When payee delivers the item/service detailed in the agreement within the deadline, the Payer is given the option to reject or do nothing. If nothing is done after 7 days, the Handshake will be Accepted. After this time, the Payee will be able to withdraw funds immediately. If the Payee rejects the item/service, there will be 14 days for both parties to work out a resolution. After that time, if the item/services remain rejected, the contract terminates.

API

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function init(address payer, uint value, uint deadline, bytes32 offchain) public

Payee initiates a Handshake to Payer, detailing a specified value and deadline.

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function initByPayer(address payee, uint value, uint deadline,bytes32 offchain) public payable

Payer initiates Handshake to Payee’s address. ETH is set in escrow, and with an accompanying deadline, after which payment will be delivered.

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function shake(uint hid, bytes32 offchain) public payable

Payer accepts a Handshake and places enough ETH in escrow to cover the value specified.

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function deliver(uint hid, bytes32 offchain) public

After the item/service has been delivered to the Payer, a notification will be sent to the Payer to review it within 7 days.

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function withdraw(uint hid, bytes32 offchain) public

Payee withdraws the escrowed ETH after the work detailed in the agreement has been reviewed by the Payer, or after 7 days have elapsed.

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function reject(uint hid, bytes32 offchain) public

Payer rejects delivered product.

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function accept(uint hid, bytes32 offchain) public

Payer accepts the delivered product.

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function cancel(uint hid, bytes32 offchain) public

Payer cancels Handshake and withdraws the escrowed ETH.

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Setup

• Clone this repository.
• Install dependency packages:

    cd handshake/
    npm install

• Compile contracts

    truffle compile --all

• Deploy contracts

    truffle migrate --reset

• Run unit tests:

    truffle test "test/basic.js"
    truffle test "test/payable.js"

Contributing

All contributions, feature requests and issue reports are welcome. Create an issue to submit your requests or notify us of a bug. If you would like to add a feature, make a pull request. Thanks for trying Handshake! Join the conversation on Telegram: https://t.me/ninja_org