Multi-signature wallet concept in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the minimum number of signatures required.

Blockchain / Solidity

uint constant MIN_SIGNATURES = [1];

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A2

B4

C1

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Setting the minimum signatures to 1 defeats the purpose of multi-signature.

Using a number higher than the total number of owners.

The minimum number of signatures required is set to 3 to ensure multi-signature security.

2fill in blank

medium

Complete the code to check if the number of collected signatures meets the minimum required.

Blockchain / Solidity

require(signaturesCount [1] MIN_SIGNATURES, "Not enough signatures");

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A<

B>=

C!=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' would reject valid transactions.

Using '!=' would allow invalid counts.

The code checks if the collected signatures are greater than or equal to the minimum required.

3fill in blank

hard

Fix the error in the function that verifies if a signer is authorized.

Blockchain / Solidity

function isAuthorized(address signer) public view returns (bool) {
    return owners[[1]];
}

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Asigner

Bmsg.sender

Caddress

Downer

Attempts:

3 left

💡 Hint

Common Mistakes

Using msg.sender instead of signer checks the wrong address.

Using 'address' or 'owner' are not valid variables here.

The function should check if the given signer address is in the owners list.

4fill in blank

hard

Fill both blanks to create a mapping that tracks signatures for each transaction.

Blockchain / Solidity

mapping(uint => mapping(address => [1])) public signatures;

function signTransaction(uint txId) public {
    signatures[txId][[2]] = true;
}

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Abool

Bmsg.sender

Cuint

Daddress

Attempts:

3 left

💡 Hint

Common Mistakes

Using uint instead of bool for signature status.

Using address instead of msg.sender to mark the signer.

The mapping stores a boolean to track if an owner signed a transaction. The signer is msg.sender.

5fill in blank

hard

Fill all three blanks to create a function that executes a transaction after enough signatures.

Blockchain / Solidity

function executeTransaction(uint txId) public {
    require(signatures[txId][[1]], "Not signed by owner");
    require(signaturesCount [2] MIN_SIGNATURES, "Insufficient signatures");
    transactions[txId].[3]();
}

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Amsg.sender

B>=

Ccall

Dtransfer

Attempts:

3 left

💡 Hint

Common Mistakes

Using transfer instead of call may not work for all transaction types.

Using '<' instead of '>=' causes logic errors.

The function checks if the caller signed, verifies enough signatures, then calls the transaction.