How to generate oauth signature in dart?

Posted by Editorial Staff | Updated on April 22, 2020

Want to generate oauth signature in dart? Use the following example code to generate oauth signature in dart.

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import 'dart:async';

import 'dart:convert';

import 'dart:math';

import 'package:http/http.dart' as http;

import 'package:convert/convert.dart';

import 'package:crypto/crypto.dart';

// TwitterApi class adapted from DanTup:

// https://blog.dantup.com/2017/01/simplest-dart-code-to-post-a-tweet-using-oauth/

class FatSecretApi {

final String fatSecretApiBaseUrl = "platform.fatsecret.com";

bool isJson = true;

final String consumerKey, consumerKeySecret, accessToken, accessTokenSecret;

Hmac _sigHasher;

FatSecretApi(this.consumerKey, this.consumerKeySecret, this.accessToken,

this.accessTokenSecret) {

var bytes = utf8.encode("$consumerKeySecret&$accessTokenSecret");

_sigHasher = new Hmac(sha1, bytes);

}

FatSecretApi forceXml() {

this.isJson = false;

return this;

}

/// Sends a tweet with the supplied text and returns the response from the Twitter API.

Future<http.Response> request(Map<String, String> data) {

if (isJson) {

data["format"] = "json";

}

return _callGetApi("rest/server.api", data);

}

Future<http.Response> _callGetApi(String url, Map<String, String> data) {

Uri requestUrl = Uri.https(fatSecretApiBaseUrl, url);

print(data["method"]);

_setAuthParams("GET", requestUrl.toString(), data);

requestUrl = Uri.https(requestUrl.authority, requestUrl.path, data);

String oAuthHeader = _generateOAuthHeader(data);

// Build the OAuth HTTP Header from the data.

// Build the form data (exclude OAuth stuff that's already in the header).

// var formData = _filterMap(data, (k) => !k.startsWith("oauth_"));

return _sendGetRequest(requestUrl, oAuthHeader);

}

void _setAuthParams(String requestMethod, String url, Map<String, String> data) {

// Timestamps are in seconds since 1/1/1970.

// var timestamp = new DateTime.now().toUtc().difference(_epochUtc).inSeconds;

var millisecondsSinceEpoch = new DateTime.now().toUtc().millisecondsSinceEpoch;

var timestamp = (millisecondsSinceEpoch / 100).round();

// Add all the OAuth headers we'll need to use when constructing the hash.

data["oauth_consumer_key"] = consumerKey;

data["oauth_signature_method"] = "HMAC-SHA1";

data["oauth_timestamp"] = timestamp.toString();

data["oauth_nonce"] = _randomString(8); // Required, but Twitter doesn't appear to use it

if (accessToken != null && accessToken.isNotEmpty) data["oauth_token"] = accessToken;

data["oauth_version"] = "1.0";

// Generate the OAuth signature and add it to our payload.

data["oauth_signature"] = _generateSignature(requestMethod, Uri.parse(url), data);

}

/// Generate an OAuth signature from OAuth header values.

String _generateSignature(String requestMethod, Uri url, Map<String, String> data) {

var sigString = _toQueryString(data);

var fullSigData = "$requestMethod&${_encode(url.toString())}&${_encode(sigString)}";

return base64.encode(_hash(fullSigData));

}

/// Generate the raw OAuth HTML header from the values (including signature).

String _generateOAuthHeader(Map<String, String> data) {

var oauthHeaderValues = _filterMap(data, (k) => k.startsWith("oauth_"));

return "OAuth " + _toOAuthHeader(oauthHeaderValues);

}

/// Send HTTP Request and return the response.

Future<http.Response> _sendGetRequest(Uri fullUrl, String oAuthHeader) async {

return await http.get(fullUrl, headers: { });

}

Map<String, String> _filterMap(

Map<String, String> map, bool test(String key)) {

return new Map.fromIterable(map.keys.where(test), value: (k) => map[k]);

}

String _toQueryString(Map<String, String> data) {

var items = data.keys.map((k) => "$k=${_encode(data[k])}").toList();

items.sort();

return items.join("&");

}

String _toOAuthHeader(Map<String, String> data) {

var items = data.keys.map((k) => "$k=\"${_encode(data[k])}\"").toList();

items.sort();

return items.join(", ");

}

List<int> _hash(String data) => _sigHasher.convert(data.codeUnits).bytes;

String _encode(String data) => percent.encode(data.codeUnits);

String _randomString(int length) {

var rand = new Random();

var codeUnits = new List.generate(

length,

(index){

return rand.nextInt(26)+97;

}

);

return new String.fromCharCodes(codeUnits);

}

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How to generate oauth signature in dart?

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