Flutter OAuth1.0 Fatsecret API Error: Invalid signature: oauth_signature 'ziNCxJykqOEMRV51C8MFx5LN%2Fi4%3D'
Anima361
i usually don't post questions here, but I've been stuck for days. I couldn't find any answers with online research either. I hope someone here can help me. I want to use the Fatsecret API with Flutter and am using OAuth1.0 for it.
I followed all the steps, created a signature base string, and then calculated the signature value using HMAC-SHA1. Unfortunately, I receive the following error:
```
Success: <?xml version="1.0" encoding="utf-8" ?>
I/flutter (10963): <error xmlns="http://platform.fatsecret.com/api/1.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://platform.fatsecret.com/api/1.0/ http://platform.fatsecret.com/api/1.0/fatsecret.xsd">
I/flutter (10963): <code>8</code>
I/flutter (10963): <message>Invalid signature: oauth_signature 'ziNCxJykqOEMRV51C8MFx5LN%2Fi4%3D'</message>
I/flutter (10963): </error>
```
I can't see where I'm going wrong. Perhaps someone might notice what I'm doing incorrectly.
My Flutter code: I have checked the consumer key and consumer secret multiple times, and they are correctly implemented in the code. For security reasons, I have entered them here simply as the string "secret".
```
import 'dart:convert';
import 'dart:math';
import 'package:crypto/crypto.dart';
import 'package:http/http.dart' as http;
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: HomeScreen(),
);
}
}
class HomeScreen extends StatefulWidget {
@override
_HomeScreenState createState() => _HomeScreenState();
}
class _HomeScreenState extends State<HomeScreen> {
int timestamp = DateTime.now().millisecondsSinceEpoch ~/ 1000;
String consumerKey = "secret"
String consumerSecret = "secret";
String url = 'https://platform.fatsecret.com/rest/server.api';
String oauthNonce = "";
String signature = "";
String getSignature() {
// Step 1: HTTP Method
String httpMethod = "POST";
// Step 2: Request URL
String encodedRequestUrl = Uri.encodeComponent(url);
// Step 3: Normalized Parameters
Map<String, String> params = {
'oauth_consumer_key': consumerKey,
'oauth_signature_method': 'HMAC-SHA1',
'oauth_timestamp': timestamp.toString(),
'oauth_nonce': oauthNonce,
'oauth_version': '1.0',
'food_id': '33691',
'method': 'food.get.v3',
};
// Sort parameters and concatenate in a string
// Sort parameters
List<String> sortedKeys = params.keys.toList()..sort();
// Concatenate parameters in a string
List<String> keyValuePairList =
sortedKeys.map((k) => '$k=${params[k]}').toList();
// Join string with '&'
String normalizedParameters = keyValuePairList.join('&');
// Encode the string
String encodedNormalizedParameters =
Uri.encodeComponent(normalizedParameters);
// Create the signature base string
String signatureBaseString =
'$httpMethod&$encodedRequestUrl&$encodedNormalizedParameters';
// HMAC-SHA1 signature
var key = utf8.encode(consumerSecret);
var bytes = utf8.encode(signatureBaseString);
var hmacSha1 = Hmac(sha1, key);
var digest = hmacSha1.convert(bytes);
String base64Signature = base64Encode(digest.bytes);
String encodedBase64Signature = Uri.encodeComponent(base64Signature);
return encodedBase64Signature;
}
void makeRequest() async {
Random rand = Random();
List<int> codeUnits = List.generate(10, (index) {
return rand.nextInt(26) + 97;
});
oauthNonce = String.fromCharCodes(codeUnits);
signature = getSignature();
final headers = {
'Content-Type': 'application/x-www-form-urlencoded',
'Authorization':
'OAuth oauth_consumer_key="$consumerKey", oauth_nonce="$oauthNonce", oauth_signature="$signature", oauth_signature_method="HMAC-SHA1", oauth_timestamp="$timestamp", oauth_version="1.0"'
};
final body = {
'food_id': '33691',
'method': 'food.get.v3',
'oauth_consumer_key': consumerKey,
'oauth_nonce': oauthNonce,
'oauth_signature': signature,
'oauth_signature_method': 'HMAC-SHA1',
'oauth_timestamp': timestamp.toString(),
'oauth_version': '1.0',
};
final response = await http.post(
Uri.parse(url),
headers: headers,
body: body,
);
if (response.statusCode == 200) {
print('Success: ${response.body}');
} else {
print('Error: ${response.body}');
}
}
@override
void initState() {
super.initState();
makeRequest();
}
@override
Widget build(BuildContext context) {
return Scaffold();
}
}
```
Дмитрий Шевченко
Anima361
I already did it now with OAuth2.0 with a Linux Server.
Дмитрий Шевченко
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