10 votes

How do you verify a contract on etherscan that is deployed by another contract?

It is not possible as on 24th March 2018. Etherscan is unable to locate contract code on the address of subcontract. Here is the transaction which deploys two contracts. But for the second contract, ...
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  • 1,640
5 votes
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How does Etherscan.io figure out constructor arguments without contract verification

This was already answered in the comments to your own previous question To summarize: The transaction that created the contract is visible on Etherscan (example here) The input data to that ...
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5 votes

How do you verify a contract on etherscan that is deployed by another contract?

I have deployed a contract from another contract: https://etherscan.io/tx/0x8fd885ce7ad7b6a591d9614d41cbb1d97aa7d2e290f6aa52531ce3d4c799a5ff which deployed: https://etherscan.io/address/...
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  • 4,067
5 votes

Verify simple smart contract on etherscan

I deployed the contract on the Kovan test net. Deployment versions same as you. Everything worked properly. I see no reason for it not to work on Ropsten. How did you deploy the contract? Maybe ...
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5 votes
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Difference between SMTChecker and Manticore?

tl;dr: you should use both (and more) :) Different FV/static analysis tools often have different features and pros/cons which might complement each other and give you better coverage. In this case, ...
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4 votes
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Unable to verify Solidity contract code on etherscan.io

I was able to verify my contract with optimization turned on, when compiling from remix: https://ethereum.github.io/browser-solidity/ For some reason, it produces a different bytecode from Parity, ...
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  • 8,907
4 votes

Why using assert, since it would consume all gas

You can use assert (over require) to indicate your intention to source code analyzers such as oyente. While require is good to validate input, it can sometimes be false because the user did something ...
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  • 50.6k
4 votes

Constructor Arguments for verification on Etherscan.io

The parameters for the constructor are appended to the contract. If you look at the "Input Data" in the contract creation transaction https://etherscan.io/tx/...
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  • 29.3k
3 votes

How do I find out what compiler version was used to deploy with MyEtherWallet

In order to deploy contract on MyEtherWallet, you need the bytecode. The bytecode contains the solidity pragma version in the metadata which is converted into the object parameter in the bytecode you ...
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  • 1,495
3 votes

Do you know online tool for abi encoding?

Yes, you can use this tool: https://abi.hashex.org. It can automatically parse constructor parameters from ABI or you can add them manually. After you enter parameter values, ABI-encoded parameters ...
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3 votes
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Cannot verify Solidity contract code on etherscan.io

Those are predeployment suggestions to reduce ambiguity at this step. The issue is there no way to be certain how the bytecode was generated because the pragma allows flexibility. If possible, ...
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2 votes
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failure to verify truffle compiled contract on ropsten.etherscan.io

You were trying to verify the "Migrations" contract that you used in your truffle configuration. You incrementer contract was the next contract you created, and can be found here: https://ropsten....
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  • 532
2 votes

ERC20 transfer function - Use "if, else" or "require"

Per https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md#transfer: The function SHOULD throw if the _from account balance does not have enough tokens to spend. So I'd say you ...
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  • 26.2k
2 votes

How to find input creation byte code for constructor argument?

An easy way to find the constructor arguments is: Browse to your contract on Etherscan and click on the tx hash for its creation On the top right, where it reads "Tools & utilities", click on the ...
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  • 7,216
2 votes

Ethereum block verification incentive

Miners want to win future blocks. If they don't independently verify that the chain they are following is the right one, they may end up spending future money doing proof of work on an incorrect chain....
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2 votes
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Token contract source code not verified

How i can do that ? Generate flat sol file from your two source files, for example, with solidity-flattener. Insert content of this flat file to "Enter the Solidity Contract Code below" field Choose ...
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2 votes
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Is the Solidity specification still its compiler?

The semantics of Solidity change with every update, and the only canonical definition is the compiler itself. Note that there is a distinction between the intended behavior of the compiler and the ...
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2 votes
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How to authenticate a smart contract

I don't think your question is unclear (someone flagged it) but it's pretty far off from the way Ethereum works conceptually. Let's start with the big one. Everything in Ethereum is deterministic, ...
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2 votes
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Can't see the source code with the new Etherscan user interface?

There's a link on the right-hand side (in "Profile Summary") labeled "Contract". Click that, and then, assuming there's verified code available, you should see a tab for the contract's code. (You ...
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  • 26.2k
2 votes

Is a contract verified and safe if it's created by a verified contract?

It depends on what you mean by "safe". You can confidently derive the source code of this contract by the source code of the deployer. It will normally happen from a statement in the form of new ...
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  • 50.6k
2 votes

cannot verify the contract address because of compiler version 0.4.9 not available in etherscan verify contract

It looks like you just deployed this contract recently. I would suggest upgrading your compiler to the latest (0.5.10 at the time of this post) or at least the latest 0.4.x compiler and redeploying. ...
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2 votes
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How is verification of transformation of raw values done on the blockchain

The blockchain is an internally consistent data structure. It is deterministic so that all nodes can verify the transitions. It cannot see the apples. That is an external reality. Generally, this is ...
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  • 50.6k
2 votes
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SPDX license when importing other people's contracts

You're right to note that this is an issue when flattening source code for Etherscan verification. There are two solutions to this. The best solution is to not flatten the source code and instead use ...
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2 votes
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Can I change the comments in a contract and still pass Etherscan verification?

Etherscan only compares the bytecode of the submitted contract to the bytecode of the deployed contract (excluding the metadata hash). So you can change any comments and the source code will still be ...
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2 votes
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Can miners choose not to verify transactions in blocks broadcast by other nodes?

The transaction will be included in the blockchain the moment it is included in a block (at least from the miner's perspective), so it doesn't need to "wait" for other nodes to verify it ...
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2 votes

Verifying token contract on Rinkeby etherscan

Short answer is: you have to create the API key at etherscan.io either for the mainnet and the rest of public testnets (Ropsten, Rinkeby, Goerli..). (Bonus) In addition, I had some issues when trying ...
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2 votes
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Properly parse contract creation bytecode metadata hash using cbor module in npm

The bytecode is not CBOR-encoded as a whole. Only the part representing the metadata hash at the end is and you seem to be decoding it correctly. As to why it can start with 0xa264, 0xa265 or ...
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  • 1,386
1 vote
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How does a miner verify the output of a smart contract?

it seems rather impossible for a miner to verify the smart contract output unless he understands the logic encoded in smart contract. Miners do understand the logic encoded in the smart contracts. ...
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  • 50.6k
1 vote

Ethereum shape analysis

We can see the application of a number of interesting formal verification tools and frameworks on Ethereum lately. In the event of rising attack vectors against the smart contract security model of ...
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1 vote

Inability to verify contract with ABIEncoderV2 on Etherscan

Verifying source code not worked for me when I tried to flatten source code to single file and upload it to etherscan.io. I think thats because pragma experimental ABIEncoderV2; in multi-file project ...
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