## Ethereum AuthMethod and Verifier
Implements support to authenticate, authorize and verify with Ethereum accounts as a did:pkh with SIWE(X) and CACAO. 
Primarly used with `did-session` and `@didtools/cacao`. 

## Installation

```
npm install --save @didtools/pkh-ethereum
```

## Auth Usage

To Auth in a web based env, use any injected Ethereum provider that implements the standard interface with `EthereumWebAuth`. A standard Ethereum provider should impelement the interface as defined by [EIP-1193](https://eips.ethereum.org/EIPS/eip-1193).

```js
// Web Auth Usage
import { EthereumWebAuth, getAccountId } from '@didtools/pkh-ethereum'
// ...

const ethProvider = // import/get your web3 eth provider
const addresses = await ethProvider.request({ method: 'eth_requestAccounts' })
const accountId = await getAccountId(ethProvider, addresses[0])

const authMethod = await EthereumWebAuth.getAuthMethod(ethProvider, accountId)
```

To Auth in a Node based env, use any standard web3 provider interface with `EthereumNodeAuth`

```js
// Node Auth Usage
import { EthereumNodeAuth, getAccountId } from '@didtools/pkh-ethereum'
// ...

const ethProvider = // import/get your web3 eth provider
const addresses = await ethProvider.request({ method: 'eth_requestAccounts' })
const accountId = await getAccountId(ethProvider, addresses[0])
const appName = 'MyNodeApp'

const authMethod = await EthereumNodeAuth.getAuthMethod(ethProvider, accountId, appName)
```

To use with did-session and reference did-session docs for more details.

```js
const client = new ComposeClient({ceramic, definition})
const resources = client.resources

const session = await DIDSession.authorize(authMethod, { resources })
client.setDID(session.did)
```

## Configuration

AuthMethod creators consume a standard Ethereum provider and an AccountId. AccountID follows the 
CAIP10 standard. The helper method `getAccountID` is provided, but you can also create an AccountID
using the CAIP library directly. 

```js
import { AccountId } from 'caip'
import { getAccountId } from '@didtools/pkh-ethereum'

const accountId = await getAccountId(ethProvider, addresses[0])

const ethMainnetChainId = '1'
const chainNameSpace = 'eip155'
const chainId = `${chainNameSpace}:${ethMainnetChainId}`
const accountIdCAIP = new AccountId({ address, chainId })

// accountId = accountIdCAIP
```

The `EthereumNodeAuth` additionally consumes an application name. The 'EthereumWebAuth' method uses your 
application domain name by default.

```js
import { EthereumNodeAuth  } from '@didtools/pkh-ethereum'

const appName = 'MyNodeApp'
const authMethod = EthereumNodeAuth.getAuthMethod(ethProvider, accountId, appName)
```

## Verifier Usage

Verifiers are needed to verify different did:pkh signed payloads using CACAO. Libraries that need them will
consume a verifiers map allowing your to register the verifiers you want to support. 

```js
import { Cacao } from '@didtools/cacao'
import { getEIP191Verifier } from '@didtools/pkh-ethereum'
import { DID } from 'dids'

const verifiers = {
	...getEIP191Verifier()
}

// Directly with cacao
Cacao.verify(cacao, { verifiers, ...opts})

// With DIDS, reference DIDS for more details
const dids = //configured dids instance
await dids.verifyJWS(jws, { capability, verifiers, ...opts})
```

## License

Apache-2.0 OR MIT