Description

CS480001 / SEC532
Blockchain: Security and Applications
Homework 2
A Secure Token Exchanger Contract

1) Implement your (probably) first ERC20 token and deploy it to the Ropsten test network. The token name must be your “[YourNameSurname]Token” (e.g., ZihniSinirToken).
Put 100 tokens to your address.
a. To see what an ERC20 token, you can read [1].
b. There are nice solidity examples in [2] including basic implementations of ERC20 tokens. You can use existing codes as is.

2) Implement another ERC token with the name
“[YourSurnameName]Token” (e.g., SinirZihniToken) and deploy it to Ropsten. Put 200 tokens to your address.

3) Add these tokens to your Metamask wallet. Take a screenshot and paste it to your report. The balances must be visible.

4) Implement a Solidity contract Exchanger that registers any number of ERC20 tokens (in your case only the two that you created) and allow an exchange among these two. This contract will have a
a. transfer function which takes two ERC20 token contract addresses (from_addrs and to_addrs as parameters. In addition, an integer value, amount, is also given.
b. If the balances of the msg.sender hold, the function decreases the from_addrs tokens and increases to_addrs tokens by amount
c. Deploy it to Ropsten.

5) Use the transfer function to transfer 10 tokens from first to the second ERC20 token you implemented.
6) See the updated balances on Metamask. Take a screenshot and paste it to your report.

7) The report must contain your all the contract codes (in the Appendix) and their addresses (all three of them) in Ropsten.

[1] https://eips.ethereum.org/EIPS/eip-20 [2] https://github.com/OpenZeppelin/openzeppelincontracts/tree/master/contracts/token/ERC20