# DRC20

[This standard](https://github.com/iclighthouse/DRC_standards/tree/main/DRC20) defines a fungible token interface suitable for interaction by both off-chain applications and on-chain smart contracts, addressing issues prevalent in IC network applications.

**Key Principles:**

* Maximize decentralization.
* Focus on core interfaces; leave out non-essential, specific functionalities.

**Improvements:**

* Account ID Compatibility: Aligns account identity using account-id, supporting `subaccount` and ensuring compatibility with `principal-id`.
* Pub/Sub Notification Model: Instead of dapps actively querying for events, this standard allows application canisters to subscribe to token canister messages using the subscribe() method. Missed messages can be retrieved with txnQuery().
* Transaction Record Storage: While Dfinity doesn't save transaction records like Ethereum, this standard recommends caching recent transactions in the token canister and using external canisters for historical data.
* Atomicity Enhancement with Lock/Execute Model: Addressing the non-atomicity of cross-canister transfers, methods like lockTransfer() and executeTransfer() ensure a two-phase transfer structure to improve atomicity.
* Preventing Duplicate Transactions: To counteract potential duplicate transactions and unclear transaction status due to network failures, the standard employs:
  * Nonce mechanism for transaction idempotency.
  * Pre-calculated txid using the DRC202 standard.
* Guarding Against Gas Attacks: Canister callers aren’t obligated to pay gas in the IC network. This standard adds a gas() method to estimate gas costs, leaving the setting of gas costs to developers.
* Tackling Malicious Approval Exploits: Adds the approvals() method allowing holders to review their approvals.
* Time-Weighted Balance: Introduces "CoinSeconds" – a time-weighted cumulative measure of account balance, aiding in calculating daily averages and balance ratios.
* Compatibility with other Token Standards: While DRC20 aligns with CTSNC, it also provides method aliases with a "drc20\_" prefix.

**Other Concerns:**

* Immutability and Decentralization: Emphasizes code immutability and equal rights with no special permissions. Canister management should be through governance canisters.
* Re-entrance Attack Prevention: Requires callers to pay gas, uses pub/sub for notifications, and updates state before external calls.
* Mint and Burn Methods: Suggests avoiding built-in mint() and burn() methods, leaving their inclusion to developers. The burn() method can utilize a specific blackhole address if required.807077e900000000000000000000000000000000000000000000000000000000(this's 0 address with checksum) can be used as the blackhole address.


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