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Formalize IPFS hash into ENS(Ethereum Name Service) resolver #1062

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merged 9 commits into from
May 7, 2018
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---
eip: 1062
title: Formalize IPFS hash into ENS(Ethereum Name Service) resolver
author: Phyrex Tsai <[email protected]>, Portal Network Team
discussions-to: https://ethereum-magicians.org/t/eip-1062-formalize-ipfs-hash-into-ens-ethereum-name-service-resolver/281
status: Draft
type: Standards Track
category: ERC
created: 2018-05-02
---

## Simple Summary
To specify the mapping protocol between resources stored on IPFS and ENS(Ethereum Naming Service).

## Abstract
The following standard details the implementation of how to combine the IPFS cryptographic hash unique fingerprint with ENS public resolver. This standard provides a functionality to get and set IPFS online resources to ENS resolver.

We think that this implementation is not only aim to let more developers and communities to provide more use cases, but also leverage the human-readable features to gain more user adoption accessing decentralized resources. We considered the IPFS ENS resolver mapping standard a cornerstone for building future Web3.0 service.

## Motivation
To build fully decentralized web service, it’s necessary to have a decentralized file storage system. Here comes the IPFS, for three following advantages :
- Address large amounts of data, and has unique cryptographic hash for every record.
- Since IPFS is also based on peer to peer network, it can be really helpful to deliver large amounts of data to users, with safer way and lower the millions of cost for the bandwidth.
- IPFS stores files in high efficient way via tracking version history for every file, and removing the duplications across the network.

Those features makes perfect match for integrating into ENS, and these make users can easily access content through ENS, and show up in the normal browser.


## Specification
The condition now is that the IPFS file fingerprint using base58 and in the meantime, the Ethereum using hex encryption. These comes the two restrictions :
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It's "hex encoding", not "hex encryption", and it's not actually the case - Ethereum stores binary data, it just uses hex in API to encode the binary data. Internally it's stored in binary form.

- Different data type, one is string, the other is integer.
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Hex strings are encoded binary data, not integers, typically (though they can be either).

- The way to process the condition requires not only we need to transfer from IPFS to Ethereum, but also need to convert it back.

To solve these requirements, we can use binary buffer bridging that gap.
When mapping the IPFS base58 string to ENS resolver, first we convert the Base58 to binary buffer, turn the buffer to hex encrypted format, and save to the contract. Once we want to get the IPFS resources address represented by the specific ENS, we can first find the mapping information stored as hex format before, extract the hex format to binary buffer, and finally turn that to IPFS Base58 address string.


## Rationale
To implement the specification, need two methods from ENS public resolver contract, when we want to store IPFS file fingerprint to contract, convert the Base58 string identifier to the hex format and invoke the `setContent` method below :

```
function setContent(bytes32 node, bytes32 hash) public only_owner(node);
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If you're happy to change to storing full multihash values in bytes, I'd suggest renaming these to setMultihash and multihash.

Also, to be consistent with existing resolver profiles, setMultihash should be specified as optional; only the getter is strictly part of the public interface.

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@PhyrexTsai PhyrexTsai May 7, 2018

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I'd happy renaming to setMultihash and multihash and use bytes to store

```

Whenever users need to visit the ENS content, we call the `content` method to get the IPFS hex data, transfer to the Base58 format, and return the IPFS resources to use.

```
function content(bytes32 node) public view returns (bytes32);
```

## Test Cases

To implement the way to transfer from base58 to hex format and the reverse one, using the ‘multihashes’ library to deal with the problem.
The library link : [https://www.npmjs.com/package/multihashes](https://www.npmjs.com/package/multihashes)
To implement the method transfer from IPFS(Base58) to hex encryption format :

```
import multihash from 'multihashes'

export const toHex = function(ipfsHash) {
let buf = multihash.fromB58String(ipfsHash)
let digest = multihash.decode(buf).digest
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Doing this hardcodes the use of SHA2-256. Could we just store the binary multihash in a bytes field instead, which would provide forward compatibility?

This would be useful for swarm, too, who want to be able to store hash+key pairs in ENS.

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About Base58 hash convert to hex, here's a simple version just using bytes:

To implement the method transfer from IPFS(Base58) to hex encryption format :

import bs58 from 'bs58'

export const toHex = function(ipfsHash) {
  const bytes = bs58.decode(ipfsHash)
  return '0x' + bytes.toString('hex')
}

To implement the method transfer from hex encryption format to IPFS(Base58)

import bs58 from 'bs58'

export const toBase58 = function(contentHash) {
  const hex = contentHash.substring(2)
  const bytes = Buffer.from(hex, 'hex')
  return bs58.encode(bytes)
}

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That looks like it would work, yes. It looks like multihashes has toHexString and fromHexString too, though, which would probably be a better fit.

return '0x' + multihash.toHexString(digest)
}
```

To implement the method transfer from hex encryption format to IPFS(Base58) :

```
import multihash from 'multihashes'

export const toBase58 = function(contentHash) {
let hex = contentHash.substring(2)
let buf = multihash.fromHexString(hex)
return multihash.toB58String(multihash.encode(buf, 'sha2-256'))
}
```

## Implementation
The use case can be implemented as browser extension. Users can easily download the extension, and easily get decentralized resources by just typing the ENS just like we normally type the DNS to browser the website. Solve the current pain for normal people can not easily visit the total decentralized website.

The workable implementation repository : [https://github.com/PortalNetwork/portal-network-browser-extension](https://github.com/PortalNetwork/portal-network-browser-extension)

## Copyright
Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).