feat: mobile app package (#1075)

packages/mobile/src/Lib/Keychain.ts

@@ -0,0 +1,31 @@
+import { RawKeychainValue } from '@standardnotes/snjs'
+import * as RCTKeychain from 'react-native-keychain'
+
+export default class Keychain {
+  static async setKeys(keys: object) {
+    const iOSOptions = {
+      accessible: RCTKeychain.ACCESSIBLE.WHEN_UNLOCKED_THIS_DEVICE_ONLY,
+    }
+    return RCTKeychain.setGenericPassword('sn', JSON.stringify(keys), iOSOptions)
+  }
+
+  static async getKeys(): Promise<RawKeychainValue | undefined | null> {
+    return RCTKeychain.getGenericPassword()
+      .then(function (credentials) {
+        if (!credentials || !credentials.password) {
+          return null
+        } else {
+          const keys = JSON.parse(credentials.password)
+          return keys
+        }
+      })
+      .catch(function (error) {
+        console.error("Keychain couldn't be accessed! Maybe no value set?", error)
+        return undefined
+      })
+  }
+
+  static async clearKeys() {
+    return RCTKeychain.resetGenericPassword()
+  }
+}