web3_sha3 | Plasma RPC Docs

Compute the Keccak-256 hash of given data on Plasma. Useful for hash verification, smart contract development, and data integrity checks.

Returns the Keccak-256 hash (not standard SHA3-256) of the given data on Plasma.

Why Plasma? Build on an EVM Layer 1 for stablecoin payments with PlasmaBFT consensus and Reth execution with 1 second blocks, XPL gas, full EVM JSON-RPC, and debug plus txpool on Dwellir.

Important: Despite the method name, web3_sha3 computes Keccak-256, which differs from the NIST-standardized SHA3-256. Ethereum adopted Keccak before NIST finalized the SHA-3 standard with different padding.

When to Use This Method

web3_sha3 is helpful for payment app developers, wallet teams, and teams shipping Solidity contracts for dollar transfers:

Hash Verification - Confirm that your local Keccak-256 implementation matches the node's output
Smart Contract Development - Compute function selectors and event topic hashes needed for ABI encoding
Data Integrity Checks - Hash data server-side via RPC and compare against expected values
Debugging - Verify hashing results when troubleshooting transaction or contract interactions

Best Practices

Input data must be hex-encoded with a 0x prefix; plain text strings will cause errors
Use for quick Keccak-256 hashing without a client-side library, but prefer local hashing for performance
Compute function selectors by taking the first 4 bytes of the hash result

JSON-RPC request

{
  "jsonrpc": "2.0",
  "method": "web3_sha3",
  "params": ["0x68656c6c6f"],
  "id": 1
}

Code Examples

Common Use Cases

1. Function Selector Computation

Compute Solidity function selectors for ABI encoding:

JavaScript

async function getFunctionSelector(provider, signature) {
  // Convert signature to hex
  const hexSignature = '0x' + Buffer.from(signature).toString('hex');

  // Hash via RPC
  const hash = await provider.send('web3_sha3', [hexSignature]);

  // Function selector is the first 4 bytes
  const selector = hash.slice(0, 10);
  console.log(`${signature} => ${selector}`);
  return selector;
}

// Example: compute selectors for common ERC-20 functions
const selectors = {
  'transfer(address,uint256)': await getFunctionSelector(provider, 'transfer(address,uint256)'),
  'balanceOf(address)': await getFunctionSelector(provider, 'balanceOf(address)'),
  'approve(address,uint256)': await getFunctionSelector(provider, 'approve(address,uint256)'),
};

2. Hash Verification Between Local and RPC

Verify your local hashing matches the node to catch library misconfigurations:

JavaScript

async function verifyHashingConsistency(provider) {
  const testCases = [
    { input: '0x', label: 'empty bytes' },
    { input: '0x68656c6c6f', label: '"hello"' },
    { input: '0x0123456789abcdef', label: 'hex data' },
  ];

  for (const { input, label } of testCases) {
    const rpcHash = await provider.send('web3_sha3', [input]);
    const localHash = keccak256(input);

    const match = rpcHash === localHash;
    console.log(`${label}: ${match ? 'PASS' : 'FAIL'}`);

    if (!match) {
      console.error(`  RPC:   ${rpcHash}`);
      console.error(`  Local: ${localHash}`);
    }
  }
}

3. Event Topic Hash Generation

Generate event topic hashes for filtering logs:

Python

from web3 import Web3

def get_event_topic(w3, event_signature):
    """Generate the topic hash for an event signature."""
    hex_sig = '0x' + event_signature.encode().hex()
    result = w3.provider.make_request('web3_sha3', [hex_sig])
    return result['result']

w3 = Web3(Web3.HTTPProvider('https://api-plasma-mainnet.n.dwellir.com/YOUR_API_KEY'))

# Common ERC-20 event topics
topics = {
    'Transfer(address,address,uint256)': get_event_topic(w3, 'Transfer(address,address,uint256)'),
    'Approval(address,address,uint256)': get_event_topic(w3, 'Approval(address,address,uint256)'),
}

for sig, topic in topics.items():
    print(f'{sig}\n  => {topic}')

Error Handling

Error Code	Description	Solution
-32602	Invalid params	Ensure data is a valid `0x`-prefixed hex string
-32603	Internal error	Retry with exponential backoff
-32005	Rate limit exceeded	Implement rate limiting or compute hashes locally instead

eth_call - Execute a call without creating a transaction
eth_getCode - Get contract bytecode at an address
web3_clientVersion - Get node client version

Returns the Keccak-256 hash (not standard SHA3-256) of the given data on Plasma.

Why Plasma? Build on an EVM Layer 1 for stablecoin payments with PlasmaBFT consensus and Reth execution with 1 second blocks, XPL gas, full EVM JSON-RPC, and debug plus txpool on Dwellir.

When to Use This Method

web3_sha3 is helpful for payment app developers, wallet teams, and teams shipping Solidity contracts for dollar transfers:

Hash Verification - Confirm that your local Keccak-256 implementation matches the node's output
Smart Contract Development - Compute function selectors and event topic hashes needed for ABI encoding
Data Integrity Checks - Hash data server-side via RPC and compare against expected values
Debugging - Verify hashing results when troubleshooting transaction or contract interactions

Best Practices

Input data must be hex-encoded with a 0x prefix; plain text strings will cause errors
Use for quick Keccak-256 hashing without a client-side library, but prefer local hashing for performance
Compute function selectors by taking the first 4 bytes of the hash result

JSON-RPC request

{
  "jsonrpc": "2.0",
  "method": "web3_sha3",
  "params": ["0x68656c6c6f"],
  "id": 1
}

async function getFunctionSelector(provider, signature) {
  // Convert signature to hex
  const hexSignature = '0x' + Buffer.from(signature).toString('hex');

  // Hash via RPC
  const hash = await provider.send('web3_sha3', [hexSignature]);

  // Function selector is the first 4 bytes
  const selector = hash.slice(0, 10);
  console.log(`${signature} => ${selector}`);
  return selector;
}

// Example: compute selectors for common ERC-20 functions
const selectors = {
  'transfer(address,uint256)': await getFunctionSelector(provider, 'transfer(address,uint256)'),
  'balanceOf(address)': await getFunctionSelector(provider, 'balanceOf(address)'),
  'approve(address,uint256)': await getFunctionSelector(provider, 'approve(address,uint256)'),
};

2. Hash Verification Between Local and RPC

Verify your local hashing matches the node to catch library misconfigurations:

JavaScript

async function verifyHashingConsistency(provider) {
  const testCases = [
    { input: '0x', label: 'empty bytes' },
    { input: '0x68656c6c6f', label: '"hello"' },
    { input: '0x0123456789abcdef', label: 'hex data' },
  ];

  for (const { input, label } of testCases) {
    const rpcHash = await provider.send('web3_sha3', [input]);
    const localHash = keccak256(input);

    const match = rpcHash === localHash;
    console.log(`${label}: ${match ? 'PASS' : 'FAIL'}`);

    if (!match) {
      console.error(`  RPC:   ${rpcHash}`);
      console.error(`  Local: ${localHash}`);
    }
  }
}

3. Event Topic Hash Generation

Generate event topic hashes for filtering logs:

Python

from web3 import Web3

def get_event_topic(w3, event_signature):
    """Generate the topic hash for an event signature."""
    hex_sig = '0x' + event_signature.encode().hex()
    result = w3.provider.make_request('web3_sha3', [hex_sig])
    return result['result']

w3 = Web3(Web3.HTTPProvider('https://api-plasma-mainnet.n.dwellir.com/YOUR_API_KEY'))

# Common ERC-20 event topics
topics = {
    'Transfer(address,address,uint256)': get_event_topic(w3, 'Transfer(address,address,uint256)'),
    'Approval(address,address,uint256)': get_event_topic(w3, 'Approval(address,address,uint256)'),
}

for sig, topic in topics.items():
    print(f'{sig}\n  => {topic}')

Error Handling

Error Code	Description	Solution
-32602	Invalid params	Ensure data is a valid `0x`-prefixed hex string
-32603	Internal error	Retry with exponential backoff
-32005	Rate limit exceeded	Implement rate limiting or compute hashes locally instead

eth_call - Execute a call without creating a transaction
eth_getCode - Get contract bytecode at an address
web3_clientVersion - Get node client version

web3_sha3 - Plasma RPC Method

When to Use This Method

Best Practices

Code Examples

Common Use Cases

1. Function Selector Computation

2. Hash Verification Between Local and RPC

3. Event Topic Hash Generation

Error Handling

On this page

web3_sha3 - Plasma RPC Method

When to Use This Method

Best Practices

Code Examples

Common Use Cases

1. Function Selector Computation

2. Hash Verification Between Local and RPC

3. Event Topic Hash Generation

Error Handling

On this page

web3_sha3 - Plasma RPC Method

When to Use This MethodCopy Anchor Link

Best PracticesCopy Anchor Link

Code ExamplesCopy Anchor Link

Common Use CasesCopy Anchor Link

1. Function Selector ComputationCopy Anchor Link

2. Hash Verification Between Local and RPCCopy Anchor Link

3. Event Topic Hash GenerationCopy Anchor Link

Error HandlingCopy Anchor Link

Related MethodsCopy Anchor Link

On this page

web3_sha3 - Plasma RPC Method

When to Use This MethodCopy Anchor Link

Best PracticesCopy Anchor Link

Code ExamplesCopy Anchor Link

Common Use CasesCopy Anchor Link

1. Function Selector ComputationCopy Anchor Link

2. Hash Verification Between Local and RPCCopy Anchor Link

3. Event Topic Hash GenerationCopy Anchor Link

Error HandlingCopy Anchor Link

Related MethodsCopy Anchor Link

On this page

When to Use This Method

Best Practices

Code Examples

Common Use Cases

1. Function Selector Computation

2. Hash Verification Between Local and RPC

3. Event Topic Hash Generation

Error Handling

Related Methods

When to Use This Method

Best Practices

Code Examples

Common Use Cases

1. Function Selector Computation

2. Hash Verification Between Local and RPC

3. Event Topic Hash Generation

Error Handling

Related Methods