feat(key-manager): add generic signing capabilities

[mirceanis]

This PR extends the signing capabilities of the key-manager plugin.

The key-manager plugin now exposes a keyManagerSign method that accepts extra alg, enc parameters and supports extension of the parameter object.
The enc parameter indicates the encoding of the data string, defaulting to utf-8 if absent.
The alg option should indicate an algorithm to be used.
Depending on the capabilities of the KMS (one of the AbstractKeyManagementSystem implementations), different signatures can be requested.

For example:

• a KMS implementation that has direct access to key material for a Secp256k1 key should be able to support:
  • ES256K, ES256K-R, eth_signTransaction, eth_signTypedData, eth_signMessage
• a KMS implementation that is based on a web3 abstraction, would only be able to do:
  • eth_signTransaction, eth_signTypedData, and eth_signMessage

The capabilities of the KMS are recorded in the IKey.meta.algorithms array during key creation or import.
Further improvements can be made to programmatically filter for KMS or key capabilities.

This PR relates to #468

Examples:

Sign a JWS payload with ES256K:

// header with `"alg": "ES256K"`
const jwsBundle = `${encodedHeader}.${encodedPayload}`
// for this alg,the result is base64url encoded
const signature = await agent.keyManagerSign({
  algorithm: 'EdDSA',
  data: jwsBundle,
  encoding: 'utf-8', // this is the default encoding, so it could be omitted in this case
  keyRef: key.kid
})
const jwsString = `${encodedHeader}..${signature}`

Sign an ETH transaction:

// RLP encode the transaction fields
const txData = serialize({
  to: '0xce31a19193d4b23f4e9d6163d7247243bAF801c3',
  value: 300000,
  gasLimit: 43092000,
  gasPrice: 20000000000,
  nonce: 1,
})

// compute the raw transaction string
// for transaction signing, the output is the `0x` prefixed hex string representing the signed raw transaction.
const rawTx = await agent.keyManagerSign({
  algorithm: 'eth_signTransaction',
  data: txData,
  encoding: 'hex',
  keyRef: key.kid
})
// rawTx = '0xf869018504a817c80084029.......'

[codecov]

Codecov Report

Merging #529 (b49b57c) into next (88264db) will increase coverage by 4.17%.
The diff coverage is 59.88%.

@@            Coverage Diff             @@
##             next     #529      +/-   ##
==========================================
+ Coverage   67.58%   71.75%   +4.17%     
==========================================
  Files          62       72      +10     
  Lines        1530     1972     +442     
  Branches      247      326      +79     
==========================================
+ Hits         1034     1415     +381     
- Misses        400      555     +155     
+ Partials       96        2      -94     

[awoie]

In general it looks great!

It would be great to have data be of type byte array, e.g., to support CBOR in the future.

[awoie]

more of my JOSE naming schizophrenia :)

[awoie]

LGTM. It just strikes me a bit that 'Ed25519' and 'EdDSA' count as two separate algorithms although they are the same.

[mirceanis]

LGTM. It just strikes me a bit that 'Ed25519' and 'EdDSA' count as two separate algorithms although they are the same.

Yes, they are identical. I added both for compatibility.