feat: add support for signed attachments (#595)

Signed-off-by: Timo Glastra <timo@animo.id>

BREAKING CHANGE: attachment method `getDataAsJson` is now located one level up. So instead of `attachment.data.getDataAsJson()` you should now call `attachment.getDataAsJson()`

packages/core/src/crypto/JwsService.ts

@@ -0,0 +1,121 @@
+import type { Buffer } from '../utils'
+import type { Jws, JwsGeneralFormat } from './JwsTypes'
+
+import { inject, Lifecycle, scoped } from 'tsyringe'
+
+import { InjectionSymbols } from '../constants'
+import { AriesFrameworkError } from '../error'
+import { JsonEncoder, BufferEncoder } from '../utils'
+import { Wallet } from '../wallet'
+import { WalletError } from '../wallet/error'
+
+// TODO: support more key types, more generic jws format
+const JWS_KEY_TYPE = 'OKP'
+const JWS_CURVE = 'Ed25519'
+const JWS_ALG = 'EdDSA'
+
+@scoped(Lifecycle.ContainerScoped)
+export class JwsService {
+  private wallet: Wallet
+
+  public constructor(@inject(InjectionSymbols.Wallet) wallet: Wallet) {
+    this.wallet = wallet
+  }
+
+  public async createJws({ payload, verkey, header }: CreateJwsOptions): Promise<JwsGeneralFormat> {
+    const base64Payload = BufferEncoder.toBase64URL(payload)
+    const base64Protected = JsonEncoder.toBase64URL(this.buildProtected(verkey))
+
+    const signature = BufferEncoder.toBase64URL(
+      await this.wallet.sign(BufferEncoder.fromString(`${base64Protected}.${base64Payload}`), verkey)
+    )
+
+    return {
+      protected: base64Protected,
+      signature,
+      header,
+    }
+  }
+
+  /**
+   * Verify a a JWS
+   */
+  public async verifyJws({ jws, payload }: VerifyJwsOptions): Promise<VerifyJwsResult> {
+    const base64Payload = BufferEncoder.toBase64URL(payload)
+    const signatures = 'signatures' in jws ? jws.signatures : [jws]
+
+    const signerVerkeys = []
+    for (const jws of signatures) {
+      const protectedJson = JsonEncoder.fromBase64(jws.protected)
+
+      const isValidKeyType = protectedJson?.jwk?.kty === JWS_KEY_TYPE
+      const isValidCurve = protectedJson?.jwk?.crv === JWS_CURVE
+      const isValidAlg = protectedJson?.alg === JWS_ALG
+
+      if (!isValidKeyType || !isValidCurve || !isValidAlg) {
+        throw new AriesFrameworkError('Invalid protected header')
+      }
+
+      const data = BufferEncoder.fromString(`${jws.protected}.${base64Payload}`)
+      const signature = BufferEncoder.fromBase64(jws.signature)
+
+      const verkey = BufferEncoder.toBase58(BufferEncoder.fromBase64(protectedJson?.jwk?.x))
+      signerVerkeys.push(verkey)
+
+      try {
+        const isValid = await this.wallet.verify(verkey, data, signature)
+
+        if (!isValid) {
+          return {
+            isValid: false,
+            signerVerkeys: [],
+          }
+        }
+      } catch (error) {
+        // WalletError probably means signature verification failed. Would be useful to add
+        // more specific error type in wallet.verify method
+        if (error instanceof WalletError) {
+          return {
+            isValid: false,
+            signerVerkeys: [],
+          }
+        }
+
+        throw error
+      }
+    }
+
+    return { isValid: true, signerVerkeys }
+  }
+
+  /**
+   * @todo This currently only work with a single alg, key type and curve
+   *    This needs to be extended with other formats in the future
+   */
+  private buildProtected(verkey: string) {
+    return {
+      alg: 'EdDSA',
+      jwk: {
+        kty: 'OKP',
+        crv: 'Ed25519',
+        x: BufferEncoder.toBase64URL(BufferEncoder.fromBase58(verkey)),
+      },
+    }
+  }
+}
+
+export interface CreateJwsOptions {
+  verkey: string
+  payload: Buffer
+  header: Record<string, unknown>
+}
+
+export interface VerifyJwsOptions {
+  jws: Jws
+  payload: Buffer
+}
+
+export interface VerifyJwsResult {
+  isValid: boolean
+  signerVerkeys: string[]
+}

packages/core/src/crypto/JwsTypes.ts

@@ -0,0 +1,11 @@
+export interface JwsGeneralFormat {
+  header: Record<string, unknown>
+  signature: string
+  protected: string
+}
+
+export interface JwsFlattenedFormat {
+  signatures: JwsGeneralFormat[]
+}
+
+export type Jws = JwsGeneralFormat | JwsFlattenedFormat

packages/core/src/crypto/__tests__/JwsService.test.ts

@@ -0,0 +1,82 @@
+import type { Wallet } from '@aries-framework/core'
+
+import { getAgentConfig } from '../../../tests/helpers'
+import { DidKey, KeyType } from '../../modules/dids'
+import { JsonEncoder } from '../../utils'
+import { IndyWallet } from '../../wallet/IndyWallet'
+import { JwsService } from '../JwsService'
+
+import * as didJwsz6Mkf from './__fixtures__/didJwsz6Mkf'
+import * as didJwsz6Mkv from './__fixtures__/didJwsz6Mkv'
+
+describe('JwsService', () => {
+  let wallet: Wallet
+  let jwsService: JwsService
+
+  beforeAll(async () => {
+    const config = getAgentConfig('JwsService')
+    wallet = new IndyWallet(config)
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+    await wallet.initialize(config.walletConfig!)
+
+    jwsService = new JwsService(wallet)
+  })
+
+  afterAll(async () => {
+    await wallet.delete()
+  })
+
+  describe('createJws', () => {
+    it('creates a jws for the payload with the key associated with the verkey', async () => {
+      const { verkey } = await wallet.createDid({ seed: didJwsz6Mkf.SEED })
+
+      const payload = JsonEncoder.toBuffer(didJwsz6Mkf.DATA_JSON)
+      const kid = DidKey.fromPublicKeyBase58(verkey, KeyType.ED25519).did
+
+      const jws = await jwsService.createJws({
+        payload,
+        verkey,
+        header: { kid },
+      })
+
+      expect(jws).toEqual(didJwsz6Mkf.JWS_JSON)
+    })
+  })
+
+  describe('verifyJws', () => {
+    it('returns true if the jws signature matches the payload', async () => {
+      const payload = JsonEncoder.toBuffer(didJwsz6Mkf.DATA_JSON)
+
+      const { isValid, signerVerkeys } = await jwsService.verifyJws({
+        payload,
+        jws: didJwsz6Mkf.JWS_JSON,
+      })
+
+      expect(isValid).toBe(true)
+      expect(signerVerkeys).toEqual([didJwsz6Mkf.VERKEY])
+    })
+
+    it('returns all verkeys that signed the jws', async () => {
+      const payload = JsonEncoder.toBuffer(didJwsz6Mkf.DATA_JSON)
+
+      const { isValid, signerVerkeys } = await jwsService.verifyJws({
+        payload,
+        jws: { signatures: [didJwsz6Mkf.JWS_JSON, didJwsz6Mkv.JWS_JSON] },
+      })
+
+      expect(isValid).toBe(true)
+      expect(signerVerkeys).toEqual([didJwsz6Mkf.VERKEY, didJwsz6Mkv.VERKEY])
+    })
+    it('returns false if the jws signature does not match the payload', async () => {
+      const payload = JsonEncoder.toBuffer({ ...didJwsz6Mkf.DATA_JSON, did: 'another_did' })
+
+      const { isValid, signerVerkeys } = await jwsService.verifyJws({
+        payload,
+        jws: didJwsz6Mkf.JWS_JSON,
+      })
+
+      expect(isValid).toBe(false)
+      expect(signerVerkeys).toMatchObject([])
+    })
+  })
+})

packages/core/src/crypto/__tests__/__fixtures__/didJwsz6Mkf.ts

@@ -0,0 +1,26 @@
+export const SEED = '00000000000000000000000000000My2'
+export const VERKEY = 'kqa2HyagzfMAq42H5f9u3UMwnSBPQx2QfrSyXbUPxMn'
+
+export const DATA_JSON = {
+  did: 'did',
+  did_doc: {
+    '@context': 'https://w3id.org/did/v1',
+    service: [
+      {
+        id: 'did:example:123456789abcdefghi#did-communication',
+        type: 'did-communication',
+        priority: 0,
+        recipientKeys: ['someVerkey'],
+        routingKeys: [],
+        serviceEndpoint: 'https://agent.example.com/',
+      },
+    ],
+  },
+}
+
+export const JWS_JSON = {
+  header: { kid: 'did:key:z6MkfD6ccYE22Y9pHKtixeczk92MmMi2oJCP6gmNooZVKB9A' },
+  protected:
+    'eyJhbGciOiJFZERTQSIsImp3ayI6eyJrdHkiOiJPS1AiLCJjcnYiOiJFZDI1NTE5IiwieCI6IkN6cmtiNjQ1MzdrVUVGRkN5SXI4STgxUWJJRGk2MnNrbU41Rm41LU1zVkUifX0',
+  signature: 'OsDP4FM8792J9JlessA9IXv4YUYjIGcIAnPPrEJmgxYomMwDoH-h2DMAF5YF2VtsHHyhGN_0HryDjWSEAZdYBQ',
+}

packages/core/src/crypto/__tests__/__fixtures__/didJwsz6Mkv.ts

@@ -0,0 +1,28 @@
+export const SEED = '00000000000000000000000000000My1'
+export const VERKEY = 'GjZWsBLgZCR18aL468JAT7w9CZRiBnpxUPPgyQxh4voa'
+
+export const DATA_JSON = {
+  did: 'did',
+  did_doc: {
+    '@context': 'https://w3id.org/did/v1',
+    service: [
+      {
+        id: 'did:example:123456789abcdefghi#did-communication',
+        type: 'did-communication',
+        priority: 0,
+        recipientKeys: ['someVerkey'],
+        routingKeys: [],
+        serviceEndpoint: 'https://agent.example.com/',
+      },
+    ],
+  },
+}
+
+export const JWS_JSON = {
+  header: {
+    kid: 'did:key:z6MkvBpZTRb7tjuUF5AkmhG1JDV928hZbg5KAQJcogvhz9ax',
+  },
+  protected:
+    'eyJhbGciOiJFZERTQSIsImtpZCI6ImRpZDprZXk6ejZNa3ZCcFpUUmI3dGp1VUY1QWttaEcxSkRWOTI4aFpiZzVLQVFKY29ndmh6OWF4IiwiandrIjp7Imt0eSI6Ik9LUCIsImNydiI6IkVkMjU1MTkiLCJ4IjoiNmNaMmJaS21LaVVpRjlNTEtDVjhJSVlJRXNPTEhzSkc1cUJKOVNyUVlCayIsImtpZCI6ImRpZDprZXk6ejZNa3ZCcFpUUmI3dGp1VUY1QWttaEcxSkRWOTI4aFpiZzVLQVFKY29ndmh6OWF4In19',
+  signature: 'eA3MPRpSTt5NR8EZkDNb849E9qfrlUm8-StWPA4kMp-qcH7oEc2-1En4fgpz_IWinEbVxCLbmKhWNyaTAuHNAg',
+}

packages/core/src/decorators/attachment/Attachment.ts

@@ -1,3 +1,5 @@
+import type { JwsGeneralFormat } from '../../crypto/JwsTypes'
+
 import { Expose, Type } from 'class-transformer'
 import {
   IsBase64,
@@ -11,6 +13,7 @@ import {
   ValidateNested,
 } from 'class-validator'
 
+import { Jws } from '../../crypto/JwsTypes'
 import { AriesFrameworkError } from '../../error'
 import { JsonEncoder } from '../../utils/JsonEncoder'
 import { uuid } from '../../utils/uuid'
@@ -29,37 +32,14 @@ export interface AttachmentDataOptions {
   base64?: string
   json?: Record<string, unknown>
   links?: string[]
-  jws?: Record<string, unknown>
+  jws?: Jws
   sha256?: string
 }
 
 /**
  * A JSON object that gives access to the actual content of the attachment
  */
 export class AttachmentData {
-  public constructor(options: AttachmentDataOptions) {
-    if (options) {
-      this.base64 = options.base64
-      this.json = options.json
-      this.links = options.links
-      this.jws = options.jws
-      this.sha256 = options.sha256
-    }
-  }
-
-  /*
-   * Helper function returning JSON representation of attachment data (if present). Tries to obtain the data from .base64 or .json, throws an error otherwise
-   */
-  public getDataAsJson<T>(): T {
-    if (typeof this.base64 === 'string') {
-      return JsonEncoder.fromBase64(this.base64) as T
-    } else if (this.json) {
-      return this.json as T
-    } else {
-      throw new AriesFrameworkError('No attachment data found in `json` or `base64` data fields.')
-    }
-  }
-
   /**
    * Base64-encoded data, when representing arbitrary content inline instead of via links. Optional.
    */
@@ -84,14 +64,24 @@ export class AttachmentData {
    * A JSON Web Signature over the content of the attachment. Optional.
    */
   @IsOptional()
-  public jws?: Record<string, unknown>
+  public jws?: Jws
 
   /**
    * The hash of the content. Optional.
    */
   @IsOptional()
   @IsHash('sha256')
   public sha256?: string
+
+  public constructor(options: AttachmentDataOptions) {
+    if (options) {
+      this.base64 = options.base64
+      this.json = options.json
+      this.links = options.links
+      this.jws = options.jws
+      this.sha256 = options.sha256
+    }
+  }
 }
 
 /**
@@ -157,4 +147,34 @@ export class Attachment {
   @ValidateNested()
   @IsInstance(AttachmentData)
   public data!: AttachmentData
+
+  /*
+   * Helper function returning JSON representation of attachment data (if present). Tries to obtain the data from .base64 or .json, throws an error otherwise
+   */
+  public getDataAsJson<T>(): T {
+    if (typeof this.data.base64 === 'string') {
+      return JsonEncoder.fromBase64(this.data.base64) as T
+    } else if (this.data.json) {
+      return this.data.json as T
+    } else {
+      throw new AriesFrameworkError('No attachment data found in `json` or `base64` data fields.')
+    }
+  }
+
+  public addJws(jws: JwsGeneralFormat) {
+    // If no JWS yet, assign to current JWS
+    if (!this.data.jws) {
+      this.data.jws = jws
+    }
+    // Is already jws array, add to it
+    else if ('signatures' in this.data.jws) {
+      this.data.jws.signatures.push(jws)
+    }
+    // If already single JWS, transform to general jws format
+    else {
+      this.data.jws = {
+        signatures: [this.data.jws, jws],
+      }
+    }
+  }
 }