Transaction types on Celo

IMPORTANT This repo is for educational purposes only. The information provided here may be inaccurate. Please don’t rely on it exclusively to implement low-level client libraries.

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Summary

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Actively supported on Celo

Chain	Transaction type	#	Specification	Recommended	Support	Comment
	Dynamic fee transaction v2	123	CIP-64	✅	Active 🟢	Supports paying gas in custom fee currencies
	Dynamic fee transaction	2	EIP-1559 (CIP-42)	✅	Active 🟢	Typical Ethereum transaction
	Access list transaction	1	EIP-2930 (CIP-35)	❌	Active 🟢	Does not support dynamically changing base fee per gas
	Legacy transaction	0	Ethereum Yellow Paper (CIP-35)	❌	Active 🟢	Does not support dynamically changing base fee per gas

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Scheduled for deprecation on Celo

Chain	Transaction type	#	Specification	Recommended	Support	Comment
	Dynamic fee transaction	124	CIP-42	❌	Security 🟠	Deprecation warning published in Gingerbread hard fork
	Legacy transaction	0	Celo Mainnet launch (Blockchain client v1.0.0)	❌	Security 🟠	Deprecation warning published in Gingerbread hard fork

• Active support 🟢: the transaction type is supported and recommended for use.
• Security support 🟠: the transaction type is supported but not recommended for use because it might be deprecated in the future.
• Deprecated 🔴: the transaction type is not supported and not recommended for use.

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Client library support

• = support for the recommended Ethereum transaction type (2)
• = support for the recommended Celo transaction type (123)
• ✅ = available
• ❌ = not available

Client library	Language		since		since	Comment
viem	TS/JS	✅		✅	>1.19.5	---
ethers	TS/JS	✅		❌		Support via fork in celo-ethers-wrapper
celo-ethers-wrapper	TS/JS	✅		✅	>2.0.0	---
web3js	TS/JS	✅		❌		Support via fork in contractkit
contractkit	TS/JS	✅		✅	>5.0.0	---
Web3j	Java	✅		❌		---
rust-ethers	Rust	✅		❌		---
brownie	Python	✅		❌		---

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Background

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Legacy transactions

1. the transaction parameters are RLP-encoded:
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   Ask AI

   RLP([nonce, gasprice, gaslimit, recipient, amount, data, chaindId, 0, 0])
   

2. the RLP-encoded transaction is hashed (using Keccak256).
3. the hash is signed with a private key using the ECDSA algorithm, which generates the v, r, and s signature parameters.
4. the transaction and signature parameters above are RLP-encoded to produce a valid signed transaction:
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   Ask AI

   RLP([nonce, gasprice, gaslimit, recipient, amount, data, v, r, s])
   

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Typed transactions

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Distinguishing between legacy and typed transactions

• a transaction type, is a number between 0 (0x00) and 127 (0x7f) representing the type of the transaction, and
• a transaction payload, is arbitrary byte data that encodes raw transaction parameters in compliance with the specified transaction type.

• read the first byte of a transaction
• if it’s bigger than 0x7f (127), then it’s a legacy transaction. To decode it, you must read all bytes (including the first byte just read) and interpret them as a legacy transaction.
• else, if it’s smaller or equal to 0x7f (127), then it’s a typed transaction. To decode it you must read the remaining bytes (excluding the first byte just read) and interpret them according to the specified transaction type.

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List of transaction types on Celo

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Legacy transaction (0)

NOTE This transaction type is 100% compatible with Ethereum and has no Celo-specific parameters.

• This transaction is defined as follows:
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  Ask AI

  RLP([nonce, gasprice, gaslimit, recipient, amount, data, v, r, s])
  

• It was introduced on Ethereum during Mainnet launch on Jul 30, 2015 as specified in the Ethereum Yellow Paper.
• It was introduced on Celo during the Celo Donut hard fork on May 19, 2021 as specified in CIP-35: Support for Ethereum-compatible transactions.

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Access list transaction (1)

NOTE This transaction type is 100% compatible with Ethereum and has no Celo-specific parameters.

• This transaction is defined as follows:
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  Ask AI

  0x01 || RLP([chainId, nonce, gasPrice, gasLimit, to, value, data, accessList, signatureYParity, signatureR, signatureS])
  

• It was introduced on Ethereum during the Ethereum Berlin hard fork on Apr, 15 2021 as specified in EIP-2930: Optional access lists.
• It was introduced on Celo during the Celo Donut hard fork on May 19, 2021 as specified in CIP-35: Support for Ethereum-compatible transactions.

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Dynamic fee transaction (2)

NOTE This transaction type is 100% compatible with Ethereum and has no Celo-specific parameters.

• This transaction is defined as follows:
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  Ask AI

  0x02 || RLP([chainId, nonce, maxPriorityFeePerGas, maxFeePerGas, gasLimit, to, value, data, accessList, signatureYParity, signatureR, signatureS])
  

• It was introduced on Ethereum during the Ethereum London hard fork on Aug, 5 2021 as specified in EIP-1559: Fee market change for ETH 1.0 chain.
• It was introduced on Celo during the Celo Espresso hard fork on Mar 8, 2022 as specified in CIP-42: Modification to EIP-1559

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Legacy transaction (0)

NOTE This transaction is not compatible with Ethereum and has three Celo-specific parameters: feecurrency, gatewayfeerecipient, and gatewayfee.

Warning This transaction type is scheduled for deprecation. A deprecation warning was published in the Gingerbread hard fork on Sep 26, 2023.

• This transaction is defined as follows:
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  Ask AI

  RLP([nonce, gasprice, gaslimit, feecurrency, gatewayfeerecipient, gatewayfee, recipient, amount, data, v, r, s])
  

• It was introduced on Celo during Mainnet launch on Apr 22, 2020 as specified in Blockchain client v1.0.0.

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Dynamic fee transaction (124)

NOTE This transaction is not compatible with Ethereum and has three Celo-specific parameters: feecurrency, gatewayfeerecipient, and gatewayfee.

Warning This transaction type is scheduled for deprecation. A deprecation warning was published in the Gingerbread hard fork on Sep 26, 2023.

• This transaction is defined as follows:
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  Ask AI

  0x7c || RLP([chain_id, nonce, max_priority_fee_per_gas, max_fee_per_gas, gas_limit, feecurrency, gatewayfeerecipient, gatewayfee, destination, amount, data, access_list, v, r, s])
  

• It was introduced on Celo during the Celo Espresso hard fork on Mar 8, 2022 as specified in CIP-42: Modification to EIP-1559.

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Dynamic fee transaction v2 (123)

NOTE This transaction is not compatible with Ethereum and has one Celo-specific parameter: feecurrency.

• This transaction is defined as follows:
  Copy

  Ask AI

  0x7b || RLP([chainId, nonce, maxPriorityFeePerGas, maxFeePerGas, gasLimit, to, value, data, accessList, feeCurrency, v, r, s])
  

• It was introduced on Celo during the Celo Gingerbread hard fork on Sep 26, 2023 as specified in CIP-64: New Transaction Type: Celo Dynamic Fee v2

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How to Send Transactions

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Import Dependencies

import {
  createPublicClient,
  createWalletClient,
  hexToBigInt,
  http,
  parseEther,
  parseGwei,
} from "viem";
import { privateKeyToAccount } from "viem/accounts";
import { celoAlfajores } from "viem/chains";
import "dotenv/config"; // use to read private key from environment variable

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Create Public and Wallet Client

const PRIVATE_KEY = process.env.PRIVATE_KEY;

/**
 * Boilerplate to create a viem client
 */
const account = privateKeyToAccount(`0x${PRIVATE_KEY}`);
const publicClient = createPublicClient({
  chain: celoAlfajores,
  transport: http(),
});
const walletClient = createWalletClient({
  chain: celoAlfajores, // Celo testnet
  transport: http(),
});

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Function to print Transaction receipt

function printFormattedTransactionReceipt(transactionReceipt: any) {

  const {
        blockHash,
        blockNumber,
        contractAddress,
        cumulativeGasUsed,
        effectiveGasPrice,
        from,
        gasUsed,
        logs,
        logsBloom,
        status,
        to,
        transactionHash,
        transactionIndex,
        type,
        feeCurrency,
        gatewayFee,
        gatewayFeeRecipient
    } = transactionReceipt;

  const filteredTransactionReceipt = {
        type,
        status,
        transactionHash,
        from,
        to
    };

  console.log(`Transaction details:`, filteredTransactionReceipt, `\n`);
}

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Code to send Transaction Type (0)

/**
  - Transation type: 0 (0x00)
  - Name: "Legacy"
  - Description: Ethereum legacy transaction
*/
async function demoLegacyTransactionType() {
    console.log(`Initiating legacy transaction...`);
    const transactionHash = await walletClient.sendTransaction({
    account, // Sender
    to: "0x70997970c51812dc3a010c7d01b50e0d17dc79c8", // Recipient (illustrative address)
    value: parseEther("0.01"), // 0.01 CELO
    gasPrice: parseGwei("20"), // Special field for legacy transaction type
    });

    const transactionReceipt = await publicClient.waitForTransactionReceipt({
        hash: await transactionHash,
    });

    printFormattedTransactionReceipt(transactionReceipt);
}

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Code to send Transaction Type (2)

/**
 * Transaction type: 2 (0x02)
 * Name: "Dynamic fee"
 * Description: Ethereum EIP-1559 transaction
 */
async function demoDynamicFeeTransactionType() {
    console.log(`Initiating dynamic fee (EIP-1559) transaction...`);
    const transactionHash = await walletClient.sendTransaction({
        account, // Sender
        to: "0x70997970c51812dc3a010c7d01b50e0d17dc79c8", // Recipient (illustrative address)
        value: parseEther("0.01"), // 0.01 CELO
        maxFeePerGas: parseGwei("10"), // Special field for dynamic fee transaction type (EIP-1559)
        maxPriorityFeePerGas: parseGwei("10"), // Special field for dynamic fee transaction type (EIP-1559)
    });

    const transactionReceipt = await publicClient.waitForTransactionReceipt({
        hash: await transactionHash,
    });

    printFormattedTransactionReceipt(transactionReceipt);
}

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Code to send Transaction Type (123)

/**
* Transaction type: 123 (0x7b)
* Name: "Dynamic fee"
* Description: Celo dynamic fee transaction (with custom fee currency)
*/
async function demoFeeCurrencyTransactionType() {
  console.log(`Initiating custom fee currency transaction...`);
  const transactionHash = await walletClient.sendTransaction({
      account, // Sender
      to: "0x70997970c51812dc3a010c7d01b50e0d17dc79c8", // Recipient (illustrative address)
      value: parseEther("0.01"), // 0.01 CELO
      feeCurrency: "0x874069Fa1Eb16D44d622F2e0Ca25eeA172369bC1", // cUSD fee currency
      maxFeePerGas: parseGwei("10"), // Special field for dynamic fee transaction type (EIP-1559)
      maxPriorityFeePerGas: parseGwei("10"), // Special field for dynamic fee transaction type (EIP-1559)
  });

  const transactionReceipt = await publicClient.waitForTransactionReceipt({
      hash: await transactionHash,
  });

  printFormattedTransactionReceipt(transactionReceipt);
}