feat(askar): improved hardware key support (#1968)

* feat(askar): improved hardware key support Signed-off-by: Berend Sliedrecht <sliedrecht@berend.io> * chore: resolved feedback and formatting Signed-off-by: Berend Sliedrecht <sliedrecht@berend.io> --------- Signed-off-by: Berend Sliedrecht <sliedrecht@berend.io>
openwallet-foundation · Jul 29, 2024 · 1a941e7 · 1a941e7
1 parent b387574
commit 1a941e7
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Showing 9 changed files with 229 additions and 339 deletions.
diff --git a/packages/askar/package.json b/packages/askar/package.json
@@ -34,6 +34,7 @@
     "tsyringe": "^4.8.0"
   },
   "devDependencies": {
+    "@animo-id/expo-secure-environment": "^0.0.1-alpha.0",
     "@hyperledger/aries-askar-nodejs": "^0.2.3",
     "@hyperledger/aries-askar-shared": "^0.2.3",
     "@types/bn.js": "^5.1.0",
@@ -44,6 +45,12 @@
     "typescript": "~5.5.2"
   },
   "peerDependencies": {
-    "@hyperledger/aries-askar-shared": "^0.2.3"
+    "@hyperledger/aries-askar-shared": "^0.2.3",
+    "@animo-id/expo-secure-environment": "^0.0.1-alpha.0"
+  },
+  "peerDependenciesMeta": {
+    "@animo-id/expo-secure-environment": {
+      "optional": true
+    }
   }
 }
diff --git a/packages/askar/src/secureEnvironment/index.ts b/packages/askar/src/secureEnvironment/index.ts
@@ -0,0 +1 @@
+export * from './secureEnvironment'
diff --git a/packages/askar/src/secureEnvironment/secureEnvironment.native.ts b/packages/askar/src/secureEnvironment/secureEnvironment.native.ts
@@ -0,0 +1,9 @@
+export function importSecureEnvironment() {
+  try {
+    // eslint-disable-next-line @typescript-eslint/no-var-requires
+    const secureEnvironment = require('@animo-id/expo-secure-environment')
+    return secureEnvironment
+  } catch (error) {
+    throw new Error('@animo-id/expo-secure-environment must be installed as a peer dependency')
+  }
+}
diff --git a/packages/askar/src/secureEnvironment/secureEnvironment.ts b/packages/askar/src/secureEnvironment/secureEnvironment.ts
@@ -0,0 +1,9 @@
+export function importSecureEnvironment(): {
+  sign: (id: string, message: Uint8Array) => Promise<Uint8Array>
+  getPublicBytesForKeyId: (id: string) => Uint8Array
+  generateKeypair: (id: string) => void
+} {
+  throw new Error(
+    '@animo-id/expo-secure-environment cannot be imported in Node.js. Currently, there is no hardware key support for node.js'
+  )
+}
diff --git a/packages/askar/src/wallet/AskarBaseWallet.ts b/packages/askar/src/wallet/AskarBaseWallet.ts
@@ -25,18 +25,20 @@ import {
   Key,
   TypedArrayEncoder,
   KeyBackend,
+  KeyType,
+  utils,
 } from '@credo-ts/core'
 import { CryptoBox, Store, Key as AskarKey, keyAlgFromString } from '@hyperledger/aries-askar-shared'
 import BigNumber from 'bn.js'
 
+import { importSecureEnvironment } from '../secureEnvironment'
 import {
   AskarErrorCode,
   AskarKeyTypePurpose,
   isAskarError,
   isKeyTypeSupportedByAskarForPurpose,
   keyTypesSupportedByAskar,
 } from '../utils'
-import { convertToAskarKeyBackend } from '../utils/askarKeyBackend'
 
 import { didcommV1Pack, didcommV1Unpack } from './didcommV1'
 
@@ -131,6 +133,7 @@ export abstract class AskarBaseWallet implements Wallet {
     seed,
     privateKey,
     keyType,
+    keyId,
     keyBackend = KeyBackend.Software,
   }: WalletCreateKeyOptions): Promise<Key> {
     try {
@@ -146,7 +149,14 @@ export abstract class AskarBaseWallet implements Wallet {
         throw new WalletError('Invalid private key provided')
       }
 
-      if (isKeyTypeSupportedByAskarForPurpose(keyType, AskarKeyTypePurpose.KeyManagement)) {
+      if (keyBackend === KeyBackend.SecureElement && keyType !== KeyType.P256) {
+        throw new WalletError(`Keytype '${keyType}' is not supported for the secure element`)
+      }
+
+      if (
+        isKeyTypeSupportedByAskarForPurpose(keyType, AskarKeyTypePurpose.KeyManagement) &&
+        keyBackend === KeyBackend.Software
+      ) {
         const algorithm = keyAlgFromString(keyType)
 
         // Create key
@@ -156,7 +166,7 @@ export abstract class AskarBaseWallet implements Wallet {
             ? AskarKey.fromSecretBytes({ secretKey: privateKey, algorithm })
             : seed
             ? AskarKey.fromSeed({ seed, algorithm })
-            : AskarKey.generate(algorithm, convertToAskarKeyBackend(keyBackend))
+            : AskarKey.generate(algorithm)
 
           // FIXME: we need to create a separate const '_key' so TS definitely knows _key is defined in the session callback.
           // This will be fixed once we use the new 'using' syntax
@@ -166,7 +176,7 @@ export abstract class AskarBaseWallet implements Wallet {
 
           // Store key
           await this.withSession((session) =>
-            session.insertKey({ key: _key, name: TypedArrayEncoder.toBase58(keyPublicBytes) })
+            session.insertKey({ key: _key, name: keyId ?? TypedArrayEncoder.toBase58(keyPublicBytes) })
           )
 
           key.handle.free()
@@ -181,6 +191,22 @@ export abstract class AskarBaseWallet implements Wallet {
           // Otherwise re-throw error
           throw error
         }
+      } else if (keyBackend === KeyBackend.SecureElement && keyType === KeyType.P256) {
+        const secureEnvironment = importSecureEnvironment()
+        const kid = keyId ?? utils.uuid()
+
+        // Generate a hardware-backed P-256 keypair
+        secureEnvironment.generateKeypair(kid)
+        const publicKeyBytes = secureEnvironment.getPublicBytesForKeyId(kid)
+        const publicKeyBase58 = TypedArrayEncoder.toBase58(publicKeyBytes)
+
+        await this.storeSecureEnvironmentKeyById({
+          keyType,
+          publicKeyBase58,
+          keyId: kid,
+        })
+
+        return new Key(publicKeyBytes, keyType, kid)
       } else {
         // Check if there is a signing key provider for the specified key type.
         if (this.signingKeyProviderRegistry.hasProviderForKeyType(keyType)) {
@@ -250,6 +276,16 @@ export abstract class AskarBaseWallet implements Wallet {
           // Now we can remove it from the custom record as we have imported it into Askar
           await this.deleteKeyPair(key.publicKeyBase58)
           keyPair = undefined
+        } else {
+          if (!(await this.doesSecureEnvironmentKeyExist(key.keyId))) {
+            throw new WalletError(`Secure Environment key with id '${key.keyId}' not found`)
+          }
+
+          if (Array.isArray(data[0])) {
+            throw new WalletError('Multi signature is not supported for the Secure Environment')
+          }
+
+          return Buffer.from(await importSecureEnvironment().sign(key.keyId, new Uint8Array(data as Buffer)))
         }
       }
 
@@ -482,6 +518,18 @@ export abstract class AskarBaseWallet implements Wallet {
     }
   }
 
+  private async doesSecureEnvironmentKeyExist(keyId: string): Promise<boolean> {
+    try {
+      const entryObject = await this.withSession((session) =>
+        session.fetch({ category: 'SecureEnvironmentKeyRecord', name: keyId })
+      )
+
+      return !!entryObject
+    } catch (error) {
+      throw new WalletError('Error retrieving Secure Environment record', { cause: error })
+    }
+  }
+
   private async deleteKeyPair(publicKeyBase58: string): Promise<void> {
     try {
       await this.withSession((session) => session.remove({ category: 'KeyPairRecord', name: `key-${publicKeyBase58}` }))
@@ -509,4 +557,28 @@ export abstract class AskarBaseWallet implements Wallet {
       throw new WalletError('Error saving KeyPair record', { cause: error })
     }
   }
+
+  private async storeSecureEnvironmentKeyById(options: {
+    keyId: string
+    publicKeyBase58: string
+    keyType: KeyType
+  }): Promise<void> {
+    try {
+      await this.withSession((session) =>
+        session.insert({
+          category: 'SecureEnvironmentKeyRecord',
+          name: options.keyId,
+          value: JSON.stringify(options),
+          tags: {
+            keyType: options.keyType,
+          },
+        })
+      )
+    } catch (error) {
+      if (isAskarError(error, AskarErrorCode.Duplicate)) {
+        throw new WalletKeyExistsError('Key already exists')
+      }
+      throw new WalletError('Error saving SecureEnvironment record', { cause: error })
+    }
+  }
 }
diff --git a/packages/askar/src/wallet/__tests__/AskarWallet.test.ts b/packages/askar/src/wallet/__tests__/AskarWallet.test.ts
@@ -130,7 +130,7 @@ describe('AskarWallet basic operations', () => {
     await expect(askarWallet.createKey({ seed, keyType: KeyType.P384 })).rejects.toThrow(WalletError)
   })
 
-  test('Fail to create a P256 keypair in hardware', async () => {
+  test('Fail to create a P256 keypair in the secure environment', async () => {
     await expect(
       askarWallet.createKey({ keyType: KeyType.P256, keyBackend: KeyBackend.SecureElement })
     ).rejects.toThrow(WalletError)

diff --git a/packages/core/src/crypto/Key.ts b/packages/core/src/crypto/Key.ts
@@ -9,9 +9,17 @@ export class Key {
   public readonly publicKey: Buffer
   public readonly keyType: KeyType
 
-  public constructor(publicKey: Uint8Array, keyType: KeyType) {
+  /**
+   *
+   * the identifier of the key. If not provided in the constructor the base58 encoded public key will be used as the key identifier by default
+   *
+   */
+  public keyId: string
+
+  public constructor(publicKey: Uint8Array, keyType: KeyType, keyId?: string) {
     this.publicKey = Buffer.from(publicKey)
     this.keyType = keyType
+    this.keyId = keyId ?? TypedArrayEncoder.toBase58(this.publicKey)
   }
 
   public static fromPublicKey(publicKey: Uint8Array, keyType: KeyType) {

diff --git a/packages/core/src/wallet/Wallet.ts b/packages/core/src/wallet/Wallet.ts
@@ -72,6 +72,7 @@ export interface WalletCreateKeyOptions {
   seed?: Buffer
   privateKey?: Buffer
   keyBackend?: KeyBackend
+  keyId?: string
 }
 
 export interface WalletSignOptions {