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Questions tagged [privacy]

Questions related to data and smart contract privacy. For questions related to user anonymity, use [tag:anonymity].

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26
votes
3answers
4k views

zk-SNARKs vs. Zk-STARKs vs. BulletProofs? (Updated)

zk-SNARKs, Zk-STARKs and BulletProofs are three major zero knowledge proofs to provide privacy for the blockchain technology. If we can compare them, (1) Bulletproofs and Zk-STARKs require no ...
22
votes
1answer
2k views

What are effective techniques to encrypt/decrypt data stored in a smart contract?

Rather than sending and storing plain text in a smart contract, the use case objective is to encrypt first and then subsequently access the data and decrypt at the point of use. What is the most ...
20
votes
2answers
3k views

Private info in an Ethereum smart contract

Is there any way to store info on a smart contract, and keep it a secret? If a contract has a state variable that is not public like: contract foo{ uint public publicVariable; uint notPublic;...
15
votes
4answers
1k views

How to increase my privacy on Ether accounts?

What would be the best way, if any, that one could change their address/account in order to make themselves unknown or hard to identify by people they traded with? More specifically, if I send ETH to ...
13
votes
4answers
1k views

With a ring signature mixer, will Ethereum transactions be completely anonymous?

I was reading the Serenity PoC2. The part quoted below grabbed my attention. Does it imply full anonymity for Ethereum transactions should I decide to use the ring signature mixer? Ring signature ...
12
votes
3answers
880 views

How can we write a contract that relies on hidden information?

Since a smart contract can only access (public) information on the blockchain itself, how can I make a smart contract that relies on hidden / secret information? Are there any workarounds in this ...
11
votes
3answers
4k views

Is there any way to hide a transaction?

Is there any way to hide a transaction on the Ethereum blockchain? Some blockchain have protocols that implement this by default, like Monero and Zcash. Is something similar possible on Ethereum?
10
votes
1answer
457 views

How can I configure Ethereum to run over Tor or I2P

If Tor or I2P support is not yet practical, is there a guide of best practices to help protect IP and other metadata?
9
votes
2answers
5k views

Solidity functions - private visibility

Is the following function parameter (string name) only visible to the owner contract itself? function myFunction(string name) private returns (bool) { return true; } So nobody can read / see ...
9
votes
1answer
627 views

What data will zk-SNARKs protect?

Implementing zk-SNARKs is planned in Ethereum roadmap, what data will be obfuscated? transaction sender and receiver? data in transactions? data stored in contracts? variables and methods in ...
8
votes
2answers
353 views

When a smart contract is deployed, is its source code publicly viewable?

When a smart contract is deployed to the blockchain, is the source code then publicly viewable to all participants? For example, what you see here in Etherchain. I am aware that there are some ...
8
votes
3answers
1k views

Is there a point to hide Ethereum nodes with TOR?

From a privacy perspective, is there any point in trying to torify ethereum nodes? I know there's a script to do that in bitcoin, although doing so may ironically made the bitcoin node more ...
7
votes
1answer
2k views

Should I create a new address for each transaction?

It's my understanding, when using bitcoin, it's advisable to generate a new address for every transaction. Is this also the case for Ethereum, and if so, how do I do this with Mist?
6
votes
2answers
371 views

Updated: Is it possible to hide the sender or receiver of transactions by “zk-SNARK” or “Bulletproofs”?

To support the user privacy, is it possible to hide the sender address or receiver address of transactions by "zk-SNARK" or "Bulletproofs" ? Or we’ll be able only to hide the value that is mapped to ...
6
votes
1answer
947 views

Accessibility of public variables

If I have a public state variable, does this mean that other contracts can access or even change its value? I have made a cryptocoin from here and all variables are declared as public, so I am ...
6
votes
2answers
5k views

Privacy of smart contract? How can one implement “private” smart contract on Ethereum? [duplicate]

Based on my current reading, I understand smart contract as a code visible and runnable on the whole blockchain. The smart contract code could be published by author, and everyone can verify the code ...
6
votes
1answer
2k views

Store secret data in contract [duplicate]

I know about the general open / trustless protocol of storing transactions. How would I approach a scenario here where I want to store some data in a contract on deployment, to later be retrieved by ...
5
votes
2answers
109 views

Is it safe to commit truffle build files to Github (open source)?

Regarding the json build files that Truffle produces based off of my smart contract, is it safe for this information to be treated as public? I just want to be sure it doesn't contain any sensitive ...
5
votes
1answer
256 views

Unlinkability between transactions to a smart contract

I am trying to develop an application using Ethereum and it needs to have transactions which are not linkable. I read an article by Vitalik Buterin, which speaks about it. He speaks about something ...
5
votes
1answer
2k views

Who can access private state variables?

I was reading solidity Docs and everything made sense until I got to this: What are external observers? Is it clients listening for events or is it anyone who has access to web3 api? For example, ...
5
votes
1answer
542 views

Current state of zero knowledge proofs?

Are there any current proof of concepts or implementations of zero knowledge proofs in the context of smart contracts? If not how long until we can store private data on a public blockchain?
5
votes
1answer
1k views

Ethereum Authentication/Authorization

Lately I've been thinking about how to integrate Ethereum with other non-Ethereum systems. Would it be a bad idea to import and Ethereum keypair into an external (mobile/desktop) application, which ...
5
votes
1answer
286 views

Is it possible to run a client behind an onion address?

It is possible to run a bitcoin client which only connects to onion nodes in the TOR network, like that: ./bitcoind -onion=127.0.0.1:9050 -onlynet=tor -externalip=ssapp53tmftyjmjb.onion Is something ...
4
votes
1answer
321 views

using indistinguishability obfuscation to ensure smartContract privacy

we all know the probelm of the public aspect of smart contract that harness the code privacy, do you think that APPLYING indistinguishability obfuscation to secure smart contract code resolve this ...
4
votes
1answer
469 views

Is the content of a function and the data in a smart contract publicly readable?

When I create a smart contract with some functions in it, I know anyone can execute those functions. My question is; can anyone also read the source/logic of those functions? And I've got the same ...
4
votes
1answer
490 views

Ethereum facilitation for zk-SNARKs

There has been a lot of talk about leveraging zk-SNARKs to bring privacy features to the Ethereum Blockchain. My question is, how is Ethereum facilitating the verification of zk-SNARKs at the moment, ...
4
votes
1answer
74 views

What can we tell from a contract's public address?

This is asked differently around but I haven't found an explanation as direct as I wanted to. I've read that all state variables in a contract are publicly visible (solidity docs). It's stated there: ...
4
votes
0answers
74 views

Will forthcoming ability to make transactions private hide gas usage and mining information?

I understand that people are working on allowing for more private transactions on the public Ethereum mainnet. This would involve hiding (at the very least) the from, to, value and probably input ...
3
votes
2answers
433 views

How Right to be forgotten can be applied with Dapps like Akasha?

As Akasha decentralized social network is ready to launch, I wonder how rights like "Right to be forgotten" can work as the blockchain never forget ?
3
votes
2answers
251 views

Is there a way to privately send ether?

Is there currently any way to privately send ether? If not, are there any plans in the future to implement any privacy features?
3
votes
2answers
213 views

Confidential value transfers

Is there currently any way to do confidential transactions with Ethereum for a custom token? If not, is there any work/research being done on how this might be possible?
3
votes
1answer
737 views

Hiding variables in Solidity [duplicate]

What is the best way to encrypt and decrypt a variable in Solidity so only the msg.sender and contract can see that variable?
3
votes
1answer
57 views

How to use key derivation and 'coin selection' to increase privacy, like in Bitcoin?

In Bitcoin, you can have increased privacy by never re-using addresses. A single private key can generate many addresses if you are using a key derivation scheme. In Ethereum, instead of UTXOs you ...
3
votes
1answer
29 views

What mathematical concepts do I need to master in order to understand the Aztec Procotol?

What mathematical concepts do I need to master in order to understand how privacy in the Aztec Protocol works? When I look at the white paper, I have no idea what is going on; however, I am confident ...
2
votes
2answers
888 views

Issue with New version of Metamask: Remix cannot detect the Metamask address

I have just installed Metamask version: 6.3.1 Now in Remix, the address of my account in metamask is not detected. The account box in remix remains always blank now (see picture below). Note that I ...
2
votes
3answers
1k views

Confidentiality in Blockchain

Can Blockchain miners see confidential transaction information? Since they have the public key, they decrypt the transaction for the purpose of verification. So if I am mining in Ethereum, I can tweak ...
2
votes
1answer
38 views

Masking Ethereum Address in a transaction [duplicate]

I want to hide the ethereum addresses of dApp users so that your transactions will not be traced by one who you have interaction earlier. The use case is actually similar to the application: Alice ...
2
votes
1answer
156 views

Is Ethereum blockchain public?

I have some idea of a smart contract, that based on private user tokens which stored in contract state. Every user can set his token by sending transaction to contract. But it is not secure if every ...
2
votes
1answer
710 views

How secure is this Rock Paper Scissors smart contract?

This contract has been out for a while (it's not mine). I wonder how secure it is. I understand encrypting & revealing process there, but what strikes me more is: When player1 calls method play ...
2
votes
1answer
155 views

How easy is it to obtain sensitive information that's included in an Ethereum contract?

I'm trying to understand how publicly available and easy to access the information embedded in contracts is, in plain language. Am I able to query the contracts in the Ethereum blockchain, similar to ...
2
votes
1answer
689 views

An example on using “zk-SNARK” in “smart contract”?

I read this article: https://media.consensys.net/introduction-to-zksnarks-with-examples-3283b554fc3b However, it's not clear to me a function such as zksnarkverify has been already implemented in ...
2
votes
4answers
222 views

Is it possible to obscure the owner of a non-fungible token?

Basically, I'd like to have unique records which can be transferred between parties without anyone knowing who owns a particular record until a transfer occurs, at which time only the recipient can ...
2
votes
1answer
129 views

Where can I find the snarkverify precompile (opcode) implementation in parity and the example coin mixing contract that utilizes it?

With the recent announcement of zkSNARKs support and the ZoE (ZeroCash over Ethereum) mixing contract (https://z.cash/blog/zksnarks-in-ethereum.html) Where can I find the mentioned parity branch and ...
2
votes
1answer
160 views

zk-SNARK use cases in blockchain (except payment)?

Is there other examples of using zk-SNARK for supporting "private transactions" except Zerocoin or Zchach ? (For example, is it possible to use zk-SNARK for health data ? or any other use cases in ...
2
votes
1answer
114 views

How do existing applications on the Ethereum blockchain enforce confidentiality of data?

How do current applications on the Ethereum blockchain enforce confidentiality of data? I know that the state of a contract is visible to any node on the network. Does this imply that there are no ...
2
votes
1answer
194 views

Would be possible to hide a function execution with zkSNARKs?

I read that with an hypothetical integration of zCash/zkSNARK with Ethereum, it would be possible to hide the sender, the receiver and the value of a transaction. My question is if would also be ...
2
votes
1answer
373 views

How privacy can be ensured in smart-contracts?

When a smart-contract is created following an agreement between two entities, how the state of that contract (data) can be kept secret to only the two contractors? I heard about Quorum, but how ...
2
votes
1answer
48 views

Save temporarily-shareable private data using Quorum

Can we use Quorum (or any other Ethererum variation) to save private data that can be shared with other parties for a temp period? The use case is that: A patient can share his medical data that is ...
2
votes
2answers
44 views

How to listen to inter-node communications regarding transactions

If I run a full node (say geth) in the Ethereum network, then the way things work out is that every node releases/ announces new transactions as they receive new ones. I'm assuming that my node must ...
2
votes
1answer
44 views

Revealing played value

I'm writing a smart contract where participants are asked to submit a value (1 to 1000000) in the submission period, and then reveal what that value is in the revealing period. In order to hide it ...