protected override void OnCreate (Bundle bundle)
{
base.OnCreate (bundle);
// Set our view from the "main" layout resource
SetContentView (Resource.Layout.Main);
buttonCheck = FindViewById<Button> (Resource.Id.buttonCheck);
buttonVerify = FindViewById<Button> (Resource.Id.buttonVerify);
buttonVerify.Enabled = false;
googleApiClient = new GoogleApiClient.Builder (this)
.EnableAutoManage (this, 1, result => {
Toast.MakeText (this, "Failed to connect to Google Play Services", ToastLength.Long).Show ();
})
.AddApi (SafetyNetClass.API)
.Build ();
buttonCheck.Click += async delegate {
var nonce = Nonce.Generate (); // Should be at least 16 bytes in length.
var r = await SafetyNetClass.SafetyNetApi.AttestAsync (googleApiClient, nonce);
if (r.Status.IsSuccess) {
// Store for future verification with google servers
attestationResult = r;
// Get the JSON from the JWS result by decoding
var decodedResult = r.DecodeJwsResult (nonce);
string error = null;
// Try and verify the body of the response
if (VerifyAttestResponse (decodedResult, nonce, out error)) {
Toast.MakeText (this, "Compatibility Passed!", ToastLength.Long).Show ();
buttonVerify.Enabled = true;
} else {
Toast.MakeText (this, "Compatibility Failed: " + error, ToastLength.Long).Show ();
}
} else {
// Error
Toast.MakeText (this, "Failed to Check Compatibility", ToastLength.Long).Show ();
}
};
buttonVerify.Click += async delegate {
// Validate the JWS response with Google to ensure it came from them
var valid = await attestationResult.ValidateWithGoogle (DEVELOPERS_CONSOLE_API_KEY);
if (valid)
Toast.MakeText (this, "Successfully validated response with Google!", ToastLength.Short).Show ();
else
Toast.MakeText (this, "Failed response validation with Google!", ToastLength.Short).Show ();
};
}
public static async Task <bool> ValidateWithGoogle(this ISafetyNetApiAttestationResult result, string validationApiKey)
{
const string url = "https://www.googleapis.com/androidcheck/v1/attestations/verify?key=";
var http = new HttpClient();
var jsonReq = "{ \"signedAttestation\": \"" + result.JwsResult + "\" }";
var content = new StringContent(jsonReq, Encoding.Default, "application/json");
var response = await http.PostAsync(url + validationApiKey, content);
var data = await response.Content.ReadAsStringAsync();
response.EnsureSuccessStatusCode();
var json = JsonObject.Parse(data);
if (json.ContainsKey("isValidSignature"))
{
return(json ["isValidSignature"].ToString().Trim('"').Equals("true"));
}
return(false);
}
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
// Set our view from the "main" layout resource
SetContentView(Resource.Layout.Main);
buttonCheck = FindViewById <Button> (Resource.Id.buttonCheck);
buttonVerify = FindViewById <Button> (Resource.Id.buttonVerify);
buttonVerify.Enabled = false;
googleApiClient = new GoogleApiClient.Builder(this)
.EnableAutoManage(this, 1, result => {
Toast.MakeText(this, "Failed to connect to Google Play Services", ToastLength.Long).Show();
})
.AddApi(SafetyNetClass.API)
.Build();
buttonCheck.Click += async delegate {
var nonce = Nonce.Generate(); // Should be at least 16 bytes in length.
var r = await SafetyNetClass.SafetyNetApi.AttestAsync(googleApiClient, nonce);
if (r.Status.IsSuccess)
{
// Store for future verification with google servers
attestationResult = r;
// Get the JSON from the JWS result by decoding
var decodedResult = r.DecodeJwsResult(nonce);
string error = null;
// Try and verify the body of the response
if (VerifyAttestResponse(decodedResult, nonce, out error))
{
Toast.MakeText(this, "Compatibility Passed!", ToastLength.Long).Show();
buttonVerify.Enabled = true;
}
else
{
Toast.MakeText(this, "Compatibility Failed: " + error, ToastLength.Long).Show();
}
}
else
{
// Error
Toast.MakeText(this, "Failed to Check Compatibility", ToastLength.Long).Show();
}
};
buttonVerify.Click += async delegate {
// Validate the JWS response with Google to ensure it came from them
var valid = await attestationResult.ValidateWithGoogle(DEVELOPERS_CONSOLE_API_KEY);
if (valid)
{
Toast.MakeText(this, "Successfully validated response with Google!", ToastLength.Short).Show();
}
else
{
Toast.MakeText(this, "Failed response validation with Google!", ToastLength.Short).Show();
}
};
}
public static string DecodeJwsResult(this ISafetyNetApiAttestationResult result, byte[] originalNonce)
{
return(JWT.JsonWebToken.Decode(result.JwsResult, originalNonce));
}
