Questions tagged [security]

Questions relating to application security, safety, trust, and attacks against the Ethereum software stack and blockchain system.

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2answers
459 views

Is it safe to generate an account with 256 coin flips?

Suppose one generates an account with the following procedure: Flip a coin 256 times; On a paper, write each heads as 1 and each tails as 0; Convert the 256-bit string to hex by mapping each 4-bit ...
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1answer
254 views

Are Monolithic Smart Contracts Better than Those That Are Decoupled?

The smart contract app I am writing follows what I consider good practice - it is decoupled so that a controller contract calls a logic contract which calls a storage contract. So Contract A calls ...
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3answers
4k views

How to generate multiple eth-addresses from one private key? [duplicate]

Is it possible to generate different multiple eth-addresses from one private key? The goal is to implement a JavaScript service that will allow a user to buy a subscription using cryptocurrency. ...
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2answers
769 views

How to execute Transaction without unlocking Account from Web3 UI

I am working on App that will be deployed in private blockchain. For testing I used to unlock my Account from Geth console to overcome 'could not unlock signer account'. However there is a risk of ...
3
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1answer
403 views

What attacks have been performed against the Ethereum network and contracts?

Every time I fire up a new Ethereum node, I run into that very slow patch of syncing from 2016Q3 due to a DoS attack on the network. What other attacks have been performed against the Ethereum network ...
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2answers
280 views

While using myetherwallet to generate offline transaction hash, can developer steal my private key?

To be very clear, I have used myetherwallet offline to send eth many times in the past. I went through the code for the version I saved and found no Maliciously code. Hypothetical for future ...
2
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1answer
731 views

Could private values be read by other contracts?

While studying blockchain interoperability (like BTC relay or a Dogecoin relay), it came to my mind that if the Ethereum blockchain can read another blockchain, we could use the same process to make ...
2
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1answer
496 views

What's involved in making a private chain become a sidechain of Ethereum?

"A private Ethereum-based network that had a linkage allowing ether to be securely moved from the public Ethereum main chain onto it and back would be considered to be a sidechain of the public ...
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2answers
841 views

Feasibility of blacklisting addresses

Probably a very naive question, but when attacks occur such as the etherdelta one yesterday, what's stopping having a system in place to basically freeze assets in a certain address before the ...
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2answers
592 views

How does the system enforce correct execution of smart contracts?

If I understand correctly, the smart contracts are run by the miners. What incentive do the miners have to execute the smart contracts correctly? What stops a malicious miner from changing the result, ...
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1answer
73 views

Have the curators emptied the whitelist of all splits after the 17 June attack?

Would like to understand if an imitator attack is possible in the next days? Explain if the split list of MEW https://www.myetherwallet.com/#dao-proposals reflects the whitelisting. Explain if splits ...
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1answer
417 views

What is the proof that Mainnet can't be reset?

It has been argued that the Morden testnet can be reset any time. How can one verify that this is not possible with the mainnet?
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2answers
370 views

Can the stalker attack in TheDAO be stopped?

https://github.com/slockit/dao/wiki/Why-The-Stalker-attack-is-a-non-issue#a-way-to-guarantee-you-get-your-eth says: Assuming the attacker also voted yes in all of the new Curator Proposals, in ...
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1answer
125 views

Who keeps the Ether when a transaction triggers an exception?

An audit had "Strong Recommendation: We recommend that exceptions cause all value to be returned to the sender, not the recipient." What were the technical reasons for not implementing this ...
4
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1answer
121 views

Did the spamming counter-attack on The DAO attack work to slow down the attacks?

This question was asked in the comment section of What does TheDAO counter-attack by spamming actually do? (suggested by Stephan Tual). Background links: The attacks used a recursive call ...
4
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1answer
293 views

What is the “pre-commit” scheme to defeat frontrunning attack?

I am writing to inquire feasible strategies to defeat Transaction Ordering Dependence (TOD) bugs. I learned from the best practice guideline such that we can use a so-called "pre-committed" scheme ...
4
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2answers
170 views

When a bonded node loses a bet who gets the ETH?

In Casper Proof-of-Stake, a validator needs to be a bonded node: it puts up a security deposit that can be lost if the validator misbehaves. When a bonded node misbehaves, who receives the lost ETH?
3
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1answer
449 views

How was the recursive call vulnerability attack conducted via proposal #59 when there were no Yes votes?

From Which split proposal was used to mount the recursive call vulnerability attack on The DAO?, proposal #59 is very likely the vector uses by the attacker to hack 3,641,694.241898506 Ether ($59,578,...
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0answers
1k views

Is this approach to an ethereum lottery sound and/or novel?

I'm looking at making gambling apps is ethereum. Currently made a contract that can flip a coin. After looking at this question: How can I securely generate a random number in my smart contract? and ...
3
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1answer
422 views

How to bypass account unlock prompt in geth console private testnet

How to bypass account unlock in private testnet, i want to transfer randomly between address. Is this possible, if yes how? I am looking forward to bypass the prompt in console so that i can ...
3
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2answers
2k views

MetaMask: how can I access the web3 object locally and use my own node?

I am new to Ethereum and was looking for a way to run my dApp in Chrome instead of Mist. I encountered Metamask, which would in theory fit my needs perfectly. However, from a basic web point of view,...
3
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0answers
90 views

What is an empty account if the state root is not empty?

"State-bloat" attacks led to an empty account being defined as an account that has zero balance, nonce and code. There was a disagreement on EIP 161: I disagree. An account should be considered ...
2
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1answer
83 views

Modifier for no-contract calls [duplicate]

The modifier used to check if a contract calls a function in Solidity used the assembly code extsize. I wonder why this is done. Using assembly seems very "hackish" to me (why does solidity not have a ...
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1answer
31 views

State only node

Is it possible for the network clients to just keep the latest network state (without keeping track of the past transactions) while not harming the network security? That is, is it really needed to ...
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1answer
168 views

How do short confirmation times negatively contribute to blockchain security?

The Ethereum whitepaper states: The motivation behind GHOST is that blockchains with fast confirmation times currently suffer from reduced security due to a high stale rate - because blocks take a ...
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1answer
1k views

How do we use block.number (as opposed to block.timestamp) for measuring time?

I've heard block.timestamp can be manipulated by miners, and as I am writing a contract that uses block.timestamp in crucial functions, I am wondering how best to mirror its behavior using block....
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1answer
55 views

Provide security wallet

I have a service where users can buy my product. Besides paying by card, I want to be able to allow users to pay in ETH. I think that it will correctly generate addresses for each user so that it is ...
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2answers
564 views

How to secure a private chain?

Recently I've setup a private chain on cloud (to be more accurate, it is a separate public chain), after a few days, I found that there are some strange transactions sending ether to the same account ...
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1answer
47 views

Does reentrancy attack happens as soon as the balance in storage is modified after the withdrawal?

I just saw something like this: function sub( uint a, uint b ) internal pure returns (uint) { require(b <= a, "SUB_UNDERFLOW"); return a - b; } function withdraw(...
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1answer
43 views

How can I prove my friend having changed just one word in the seed and have it lay around is super insecure?

My friend said to me that he has his seed saved in Google Drive and that he is absolutely safe even if someone found it out. He even gave me his seed to try to break it. I know that all I have to do ...
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1answer
210 views

How to avoid using tx.origin when we really need it?

It's been recommended that we should avoid using tx.origin. However, there're some cases it's really needed, like the following case. Assume we have two smart contracts: Sc1 and Sc2, both of which ...
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2answers
400 views

pragma solidity ^0.4.11; vulnarability

As stated on this website http://fluidai.co/examples/ one of Solidity's vulnerabilities is using an open version in pragma: pragma solidity ^0.4.11; You're telling the Solidity compiler to use the ...
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2answers
1k views

Division/Percentages in Solidity (a workaround)

Division/percentages is a required part of many applications but is difficult to implement since fixed and ufixed are not supported yet in Solidity. I've come up with this workaround: pragma ...

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