feat: add encryption key support for ethr-did-documents

fixes decentralized-identity#52
veramolabs · Feb 25, 2020 · 2f5825c · 2f5825c
1 parent b930dde
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diff --git a/README.md b/README.md
@@ -145,11 +145,25 @@ While any attribute can be stored. For the DID document we currently support add
 
 The name of the attribute should follow this format:
 
-`did/pub/(Secp256k1|RSA|Ed25519)/(veriKey|sigAuth)/(hex|base64)`
+`did/pub/(Secp256k1|RSA|Ed25519|X25519)/(veriKey|sigAuth|enc)/(hex|base64)`
 
-#### Hex encoded Secp256k1 Verification Key
+(Essentially `did/pub/<key algorithm>/<key purpose>/<encoding>`)
+
+#### Key purposes
+
+- `veriKey` adds a `<key algorithm>VerificationKey2018` to the `publicKey` section of document
+- `sigAuth` adds a `<key algorithm>SignatureAuthentication2018` to the `publicKey` section of document. An entry is also added to the `authentication` section of document.
+- `enc` adds a `<key algorithm>KeyAgreementKey2019` to the `publicKey` section.
+  This is used to perform a Diffie-Hellman key exchange and derive a secret key for encrypting messages to the DID that lists such a key.
+
+> **Note** The `<encoding>` only refers to the key encoding in the resolved DID document.
+> Attribute values should always be hex encoded.
 
-A `DIDAttributeChanged` event for the identity `0xf3beac30c498d9e26865f34fcaa57dbb935b0d74` with the name `did/pub/Secp256k1/veriKey/hex` and the value of `0x02b97c30de767f084ce3080168ee293053ba33b235d7116a3263d29f1450936b71` generates a `PublicKey` entry like this:
+#### Example hex encoded Secp256k1 Verification Key
+
+A `DIDAttributeChanged` event for the identity `0xf3beac30c498d9e26865f34fcaa57dbb935b0d74` with the name
+`did/pub/Secp256k1/veriKey/hex` and the value of `0x02b97c30de767f084ce3080168ee293053ba33b235d7116a3263d29f1450936b71`
+generates a `PublicKey` entry like this:
 
 ```javascript
 {
@@ -162,7 +176,9 @@ A `DIDAttributeChanged` event for the identity `0xf3beac30c498d9e26865f34fcaa57d
 
 #### Base64 encoded Ed25519 Verification Key
 
-A `DIDAttributeChanged` event for the identity `0xf3beac30c498d9e26865f34fcaa57dbb935b0d74` with the name `did/pub/Ed25519/veriKey/base64` and the value of `0xb97c30de767f084ce3080168ee293053ba33b235d7116a3263d29f1450936b71` generates a `PublicKey` entry like this:
+A `DIDAttributeChanged` event for the identity `0xf3beac30c498d9e26865f34fcaa57dbb935b0d74` with the name
+`did/pub/Ed25519/veriKey/base64` and the value of
+`0xb97c30de767f084ce3080168ee293053ba33b235d7116a3263d29f1450936b71` generates a `PublicKey` entry like this:
 
 ```javascript
 {
@@ -173,6 +189,22 @@ A `DIDAttributeChanged` event for the identity `0xf3beac30c498d9e26865f34fcaa57d
 }
 ```
 
+#### Base64 encoded X25519 Encryption Key
+
+A `DIDAttributeChanged` event for the identity `0xf3beac30c498d9e26865f34fcaa57dbb935b0d74` with the name
+`did/pub/X25519/enc/base64` and the value of
+`0x302a300506032b656e032100118557777ffb078774371a52b00fed75561dcf975e61c47553e664a617661052`
+generates a `PublicKey` entry like this:
+
+```javascript
+{
+  id: "did:ethr:0xf3beac30c498d9e26865f34fcaa57dbb935b0d74#delegate-1",
+  type: "X25519KeyAgreementKey2019",
+  owner: "did:ethr:0xf3beac30c498d9e26865f34fcaa57dbb935b0d74",
+  publicKeyBase64: "MCowBQYDK2VuAyEAEYVXd3/7B4d0NxpSsA/tdVYdz5deYcR1U+ZkphdmEFI="
+}
+```
+
 We are looking for people to submit support for `pem`, `base58` and `jwk` key formats as well.
 
 ### Service Endpoints
@@ -183,7 +215,9 @@ The name of the attribute should follow this format:
 
 #### Hex encoded Secp256k1 Verification Key
 
-A `DIDAttributeChanged` event for the identity `0xf3beac30c498d9e26865f34fcaa57dbb935b0d74` with the name `did/svc/HubService` and value of the url `https://hubs.uport.me` hex encoded as `0x68747470733a2f2f687562732e75706f72742e6d65` generates a `Service` entry like this:
+A `DIDAttributeChanged` event for the identity `0xf3beac30c498d9e26865f34fcaa57dbb935b0d74` with the name
+`did/svc/HubService` and value of the url `https://hubs.uport.me` hex encoded as
+`0x68747470733a2f2f687562732e75706f72742e6d65` generates a `Service` entry like this:
 
 ```javascript
 {
@@ -195,7 +229,8 @@ A `DIDAttributeChanged` event for the identity `0xf3beac30c498d9e26865f34fcaa57d
 ## Resolving a DID document
 
 The library presents a `resolver()` function that returns a ES6 Promise returning the DID document.
-It is not meant to be used directly but through the [`did-resolver`](https://github.com/decentralized-identity/did-resolver) aggregator.
+It is not meant to be used directly but through the
+[`did-resolver`](https://github.com/decentralized-identity/did-resolver) aggregator.
 You can use the `getResolver(conf)` method to produce an entry that can be used with the `Resolver`
 constructor.
 

diff --git a/src/__tests__/ethr-did-resolver-test.js b/src/__tests__/ethr-did-resolver-test.js
@@ -507,6 +507,51 @@ describe('ethrResolver', () => {
           })
         })
       })
+
+      describe('X25519KeyAgreementKey2019', () => {
+        let identity1, did1
+
+        beforeAll(async () => {
+          const accounts = await getAccounts()
+          identity1 = accounts[5]
+          did1 = `did:ethr:${identity1}`
+
+          await registry.setAttribute(
+            identity1,
+            stringToBytes32('did/pub/X25519/enc/base64'),
+            `0x${Buffer.from('MCowBQYDK2VuAyEAEYVXd3/7B4d0NxpSsA/tdVYdz5deYcR1U+ZkphdmEFI=', 'base64').toString('hex')}`,
+            86400,
+            { from: identity1 }
+          )
+        })
+
+        it('resolves document', () => {
+          return expect(didResolver.resolve(did1)).resolves.toEqual({
+            '@context': 'https://w3id.org/did/v1',
+            id: did1,
+            publicKey: [
+              {
+                id: `${did1}#owner`,
+                type: 'Secp256k1VerificationKey2018',
+                owner: did1,
+                ethereumAddress: identity1
+              },
+              {
+                id: `${did1}#delegate-1`,
+                type: 'X25519KeyAgreementKey2019',
+                owner: did1,
+                publicKeyBase64: 'MCowBQYDK2VuAyEAEYVXd3/7B4d0NxpSsA/tdVYdz5deYcR1U+ZkphdmEFI='
+              }
+            ],
+            authentication: [
+              {
+                type: 'Secp256k1SignatureAuthentication2018',
+                publicKey: `${did1}#owner`
+              }
+            ]
+          })
+        })
+      })
     })
 
     describe('add service endpoints', () => {

diff --git a/src/ethr-did-resolver.js b/src/ethr-did-resolver.js
@@ -29,7 +29,8 @@ const delegateTypes = {
 
 const attrTypes = {
   sigAuth: 'SignatureAuthentication2018',
-  veriKey: 'VerificationKey2018'
+  veriKey: 'VerificationKey2018',
+  enc: 'KeyAgreementKey2019'
 }
 
 function wrapDidDocument (did, owner, history) {