DeviceCheck API - Unique Identifier for the iOS Devices?

Question

When using the device check, it Generates the new token every time like below,

Generated Token :

eyJiaXQwIjpmYWxzZSwidG9rZW4iOiJBZ0FBQUVMcFdkRkZXdkF0aE5CUU80Zyt3V1FFVU5rMCttZTg5dkxmdjVaaW5ncHlPT2tnWFhYeWpQellUeldtV1N1K0JZcWNENDdieWlyTForKzNkSmNjcEY5OWhXcHBUN0c1eEF1VSt5NTZXcFNZc0FRTVVyaTJZSGplTVo3NmJnM3hqa1ozTnZpdFM2Q3NoWFJPNUVl

Using bit values along with token we can find the device is present or not in the apple, even if we uninstall the app. But how it can be useful for uniquely identifying a device.

Success response:

{"status":200,"bit0":false,"bit1":false,"lastUpdated":"2018-10"}

Server request:

{

"device_token" : "wlkCDA2Hy/m5jQ1cs..." "transaction_id" : "4-w3d4-567-2376674f8uj8", "timestamp" : 1487716472000

}

This is the link i used for my code :

https://github.com/marinosoftware/DeviceCheckSample

Answer 1

very intentionally by Apple, DeviceCheck tokens can not be used to identify the specific device.

Answer 2

As you say apple allow us to store two bits. it means we can store four state for that device.

we can't identify specific device!, but we can check whether device is used for four different purpose.

Ex.

Bit0  |  Bit1  |  State name 
  0   |   0    |  app installed
  0   |   1    |  app installed + sign in
  1   |   0    |  app installed + sign in + redeem sign up coupon code 
  1   |   1    |  device is blacklisted