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iExecBlockchainComputing / iexec-apps

Dockerfile of all iExec apps
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Bounty #4 - TLS Notary DOracle #13

Closed julienbrg closed 4 years ago

julienbrg commented 5 years ago

What you will learn

Prerequisite

App requirements

What I need to do?

An iExec DOracle needs two parts: Off-chain dockerized application, and on-chain smart contract.

1. Dockerized application (off-chain) You need to write a logic that does the following steps:

Then, push you docker image on Dockerhub, and deploy it on iExec using the SDK.

2. Smart contract (on-chain)

Going further: About Decentralized Oracles (optional read)

Programmable blockchains and smart contracts are a big deal, but they live in siloed environments and as such have very limited access to the outside world (i.e. the Internet). The iExec V3 makes it trivial for anyone to deploy his own decentralized oracle, hence allowing developers to leverage the terabytes of data available on the Web 2.0 to build a whole new range of useful and impactful dapps without compromising on the security.

The iExec DOracle uses iExec to execute the oracle logic off-chain and return certified results to the blockchain. Certification can be achieved using a combination of hardware security (TEE - Trusted Execution Environment) and on-chain consensus (iExec’s PoCo). These two mechanism provides tools to ensure results of a DOracle execution can be trusted for the on-chain settlement of off-chain events.

Documentation of the iExec platform, including details about de PoCo protocol can be found at https://docs.iex.ec.

Components of an iExec DOracle.

In order to run, an iExec DOracle needs three essential components:

  1. A dockerized application = off-chain logic that fetches the data your dapp needs.
  2. The output = The data your on-chain dapp needs.
  3. A receiving smart contract = The smart contract that will consume the output.

The app & the output

The dockerized oracle app contains the logic that will be executed and verified by the iExec platform when a call is requested. This logic can be implemented in any language and access any data as long as it can be dockerized and it follows below simple guidelines:

  1. Given a set of input parameters, multiple execution of the same app must provide the exact same results (we say it is a deterministic application).
  2. Output must be encoded in a way that makes it readable on the blockchain. Consider using the abi.encode format.
  3. The result fetched by the appEncoded results (bytes) must be written to the /iexec_out/callback.iexec file. Additionnaly the keccak256 hash of the results (bytes32) must be written to the /iexec_out/determinism.iexec file.

The iExec middleware will perform the consensus on the determinism.iexec file, and will store the callback.iexec file on Ethereum.

The receiving smart contract

The receiving smart contract will be the on-chain receiver that will consume the output. This contract can contain any logic, but it should inherit from the IexecDoracle (available on Github) which provides a routine to retrieve and verify the result of an oracle execution. The PriceOracle shows a good example of such contract.

Security considerations

The iExec framework proposes all the tools to build a secure decentralized oracle. However, simply using the iExec framework won’t prevent issues in the oracle design from threatening the security and the decentralization of the oracle. Here are some points that should be considered:

External resources (such as Web 2.0 APIs) are centralized point of failure. DOracles can forward data from such APIs to the blockchain in a trustless manner, but the data reported on-chain is still subject to manipulation by the API administrator.

If trying to report random values from an off-chain source to the blockchain, be aware that the requester of the call might be able to control the seed. You may want to use additional proof of origin or use commit reveal pattern that only accept oracle calls for which the request has been registered on-chain before the actual value was predictable. In general, providing cryptographically secure randomness to a blockchain is difficult, so don’t try it unless you really understand the different attack vectors.

Design your receiver smart contract to be trustless and censorship resistant. If only a single actor can update it then your oracle might not be properly designed. Anyone with an interest on updating a value must be able to pay for an oracle call that will provided an updated value to the blockchain which nobody can argue against.

Need help?

Again, the documentation is here: https://docs.iex.ec. Feel free to ask for more information on our Slack.

gitcoinbot commented 5 years ago

Issue Status: 1. Open 2. Started 3. Submitted 4. Done

This issue now has a funding of 300.0 RLC attached to it as part of the iExecBlockchainComputing fund.

gitcoinbot commented 5 years ago

Issue Status: 1. Open 2. Cancelled

Work has been started.

These users each claimed they can complete the work by 1 year, 8 months ago. Please review their action plans below:

1) erazhu31 has been approved to start work.

Hi i would like to complete it. i worked on others bounties. thanks

Learn more on the Gitcoin Issue Details page.

sulliwane commented 5 years ago

Hi @erazhu31,

Thank you for your interest in learning how to build a Decentralized Oracle.

Congrats, we just approved your application.

Let's start!

  1. Please join our Slack #tech-support channel so that you can ask your questions to the iExec tech team.
  2. Please post your Slack username in this thread (so we clearly make the link between your profiles).
  3. Make sure you read the article: How to build a Decentralized Oracle on Ethereum — A Step-by-Step Guide.

Don't forget to push your code as a PR in this repo so we can review it.

As soon as your DOracle is working, the RLC are yours!

Reminder: That's is part of the Learn iExec & Earn RLC program.

gitcoinbot commented 5 years ago

@erazhu31 Hello from Gitcoin Core - are you still working on this issue? Please submit a WIP PR or comment back within the next 3 days or you will be removed from this ticket and it will be returned to an ‘Open’ status. Please let us know if you have questions!

Funders only: Snooze warnings for 1 day | 3 days | 5 days | 10 days | 100 days

erazhu31 commented 5 years ago

hi still working on it thanks

sulliwane commented 5 years ago

Ok, no problem. Let us know when your PR is ready! Good luck @erazhu31 :)

gitcoinbot commented 5 years ago

Issue Status: 1. Open 2. Started 3. Submitted 4. Done

@erazhu31 due to inactivity, we have escalated this issue to Gitcoin's moderation team. Let us know if you believe this has been done in error!

Funders only: Snooze warnings for 1 day | 3 days | 5 days | 10 days | 100 days

erazhu31 commented 5 years ago

hi i will provide a pr soon thanks

gitcoinbot commented 5 years ago

@erazhu31 Hello from Gitcoin Core - are you still working on this issue? Please submit a WIP PR or comment back within the next 3 days or you will be removed from this ticket and it will be returned to an ‘Open’ status. Please let us know if you have questions!

Funders only: Snooze warnings for 1 day | 3 days | 5 days | 10 days | 100 days

gitcoinbot commented 5 years ago

Issue Status: 1. Open 2. Started 3. Submitted 4. Done

@erazhu31 due to inactivity, we have escalated this issue to Gitcoin's moderation team. Let us know if you believe this has been done in error!

Funders only: Snooze warnings for 1 day | 3 days | 5 days | 10 days | 100 days

erazhu31 commented 5 years ago

Hi i did a PR

App is deployed here ✔ Deployed new app at address 0x812da479c0fc3DEDAe6d81F733468cF5b90201b8 contract is here TlsNotaryOracle deployed at address: 0xC6e7243F736Ab79592a3b2Be80D43D6DF502A604

Thanks

erazhu31 commented 5 years ago

Thanks for the tips

emmaodia commented 4 years ago

@sulliwane @julienbrg If this bounty is still open, I want to work on it. I implement the Bank Card Payment validator. I can submit a PR for this in the next 2 days. Thank you!

sulliwane commented 4 years ago

Hi @emmaodia, Yes the bounty is still open. But TLS Notary is a special beast :) It's probably a bit more complicated than other bounties (you can have a look at this existing PR and the review: https://github.com/iExecBlockchainComputing/iexec-apps/pull/27). You are welcome to give it a try!

emmaodia commented 4 years ago

SWEET! I'm up for the challenge! Thanks.

emmaodia commented 4 years ago

Hi @sulliwane I have submitted a PR here: https://github.com/iExecBlockchainComputing/iexec-apps/pull/42

emmaodia commented 4 years ago

Hello @julienbrg @sulliwane Kindly review my PR. Thank you.

emmaodia commented 4 years ago

@sulliwane @julienbrg Please can I get feedback on my PR. Thanks. :+1:

sulliwane commented 4 years ago

Hi @emmaodia, I'm very sorry for the delay! The tech team being back from holiday since less than a week, they are still very busy. As soon as @Amxx has some time, he'll review your PR. Don't worry, the bounty is locked in Gitcoin and if the review is OK, the RLC will be yours ;) Thanks a lot for your patience!

emmaodia commented 4 years ago

Great! That is fine @sulliwane. I'm even more excited to hear from you! Thank you for taking the time. Okay. Patiently waiting for @Amxx. Thanks.

gitcoinbot commented 4 years ago

Issue Status: 1. Open 2. Cancelled

The funding of 300.0 RLC (200.34 USD @ $0.67/RLC) attached to this issue has been cancelled by the bounty submitter

sulliwane commented 4 years ago

Hi @emmaodia, sorry to let you know that we finally decided to cancel the TLS Notary issue, as it was not understood correctly by most of the contributors. Thanks anyway for your contribution, and stay tuned as more bounties are to come :) Cheers!