为 Firebase 生成 JWT

时间：2023-06-03

本文介绍了为 Firebase 生成 JWT的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

限时送ChatGPT账号..

我正在尝试为 Windows 上的 C# .NET 编写自定义 JWT 令牌生成器，以便在 Google Firebase 中使用.我从 StackOverflow 上的几个不同地方提取的源代码(我正在尝试重新发现它们，以便我可以信任原作者并提出一些额外的问题)，所以它有点像大杂烩.

I'm trying to write a custom JWT token generator for C# .NET on Windows for use in Google Firebase. The source I lifted from a few different places here on StackOverflow (I'm trying to re-discover them so I can credit the original authors and ask a couple of additional questions too), so it's a bit of a hodge-podge together.

在大多数情况下，它似乎可以工作，但它似乎没有按预期生成有效的(firebase)令牌.这可能完全是因为我最初对它应该如何工作缺乏了解，但如果我能从这里获得第二双世界级的工程师的眼睛，指出我做错了什么并让事情顺利进行，那会很好.

For the most part it seems to work, but it doesn't seem to generate a valid (firebase) token as expected. This could be entirely due to my lack of understanding of how it should work in the first place, but if I could get a second pair of world-class-awesome-engineers eyes from here to point out what I did wrong and make things work, it would be nice.

代码如下:

// Token generator setup
using Newtonsoft.Json;
using System;
using System.IO;
using System.Web;
using System.Web.Configuration;

namespace myapp.Utils
{
    public class GoogleJsonWebToken
    {
        public static string Encode(string uid)
        {
            var utc0 = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
            var issueTime = DateTime.Now;

            var iat = (int)issueTime.Subtract(utc0).TotalSeconds;
            var exp = (int)issueTime.AddMinutes(60).Subtract(utc0).TotalSeconds;

            var firebaseInfPath = HttpContext.Current.Server.MapPath(WebConfigurationManager.AppSettings["firebaseInf"]);
            var firebaseInfJsonContent = File.ReadAllText(firebaseInfPath);
            var firebaseInf = JsonConvert.DeserializeObject<dynamic>(firebaseInfJsonContent);
            var privateKey = (string)firebaseInf.private_key;

            var payload = new
            {
                iss = firebaseInf.client_email,
                scope = firebaseInf.client_email,
                aud = "https://identitytoolkit.googleapis.com/google.identity.identitytoolkit.v1.IdentityToolkit",
                exp = exp,
                uid = uid,
                iat = iat,
                claims = new { premium_account = true }
            };

            return myapp.Utils.JsonWebToken.Encode(payload, privateKey, JwtHashAlgorithm.RS256);
        }
    }
}

JWT 哈希算法代码如下:

Here's the JWT hash algorithm code:

// JsonWebToken.cs
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Text;

namespace myapp.Utils
{
    public enum JwtHashAlgorithm
    {
        RS256,
        HS384,
        HS512
    }

    public class JsonWebToken
    {
        private static Dictionary<JwtHashAlgorithm, Func<byte[], byte[], byte[]>> HashAlgorithms;

        static JsonWebToken()
        {
            HashAlgorithms = new Dictionary<JwtHashAlgorithm, Func<byte[], byte[], byte[]>>
            {
                { JwtHashAlgorithm.RS256, (key, value) => { using (var sha = new HMACSHA256(key)) { return sha.ComputeHash(value); } } },
                { JwtHashAlgorithm.HS384, (key, value) => { using (var sha = new HMACSHA384(key)) { return sha.ComputeHash(value); } } },
                { JwtHashAlgorithm.HS512, (key, value) => { using (var sha = new HMACSHA512(key)) { return sha.ComputeHash(value); } } }
            };
        }

        public static string Encode(object payload, string key, JwtHashAlgorithm algorithm)
        {
            var keyBytes = Encoding.UTF8.GetBytes(key);
            return Encode(payload, keyBytes, algorithm);
        }

        public static string Encode(object payload, byte[] keyBytes, JwtHashAlgorithm algorithm)
        {
            var segments = new List<string>();
            var header = new { alg = algorithm.ToString(), typ = "JWT" };

            byte[] headerBytes = Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(header, Formatting.None));
            byte[] payloadBytes = Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(payload, Formatting.None));
            //byte[] payloadBytes = Encoding.UTF8.GetBytes(@"{"iss":"761326798069-r5mljlln1rd4lrbhg75efgigp36m78j5@developer.gserviceaccount.com","scope":"https://www.googleapis.com/auth/prediction","aud":"https://accounts.google.com/o/oauth2/token","exp":1328554385,"iat":1328550785}");

            segments.Add(Base64UrlEncode(headerBytes));
            segments.Add(Base64UrlEncode(payloadBytes));

            var stringToSign = string.Join(".", segments.ToArray());

            var bytesToSign = Encoding.UTF8.GetBytes(stringToSign);

            byte[] signature = HashAlgorithms[algorithm](keyBytes, bytesToSign);
            segments.Add(Base64UrlEncode(signature));

            return string.Join(".", segments.ToArray());
        }

        public static string Decode(string token, string key)
        {
            return Decode(token, key, true);
        }

        public static string Decode(string token, string key, bool verify)
        {
            var parts = token.Split('.');
            var header = parts[0];
            var payload = parts[1];
            byte[] crypto = Base64UrlDecode(parts[2]);

            var headerJson = Encoding.UTF8.GetString(Base64UrlDecode(header));
            var headerData = JObject.Parse(headerJson);
            var payloadJson = Encoding.UTF8.GetString(Base64UrlDecode(payload));
            var payloadData = JObject.Parse(payloadJson);

            if (verify)
            {
                var bytesToSign = Encoding.UTF8.GetBytes(string.Concat(header, ".", payload));
                var keyBytes = Encoding.UTF8.GetBytes(key);
                var algorithm = (string)headerData["alg"];

                var signature = HashAlgorithms[GetHashAlgorithm(algorithm)](keyBytes, bytesToSign);
                var decodedCrypto = Convert.ToBase64String(crypto);
                var decodedSignature = Convert.ToBase64String(signature);

                if (decodedCrypto != decodedSignature)
                {
                    throw new ApplicationException(string.Format("Invalid signature. Expected {0} got {1}", decodedCrypto, decodedSignature));
                }
            }

            return payloadData.ToString();
        }

        private static JwtHashAlgorithm GetHashAlgorithm(string algorithm)
        {
            switch (algorithm)
            {
                case "RS256": return JwtHashAlgorithm.RS256;
                case "HS384": return JwtHashAlgorithm.HS384;
                case "HS512": return JwtHashAlgorithm.HS512;
                default: throw new InvalidOperationException("Algorithm not supported.");
            }
        }

        // from JWT spec
        private static string Base64UrlEncode(byte[] input)
        {
            var output = Convert.ToBase64String(input);
            output = output.Split('=')[0]; // Remove any trailing '='s
            output = output.Replace('+', '-'); // 62nd char of encoding
            output = output.Replace('/', '_'); // 63rd char of encoding
            return output;
        }

        // from JWT spec
        private static byte[] Base64UrlDecode(string input)
        {
            var output = input;
            output = output.Replace('-', '+'); // 62nd char of encoding
            output = output.Replace('_', '/'); // 63rd char of encoding
            switch (output.Length % 4) // Pad with trailing '='s
            {
                case 0: break; // No pad chars in this case
                case 2: output += "=="; break; // Two pad chars
                case 3: output += "="; break; // One pad char
                default: throw new System.Exception("Illegal base64url string!");
            }
            var converted = Convert.FromBase64String(output); // Standard base64 decoder
            return converted;
        }
    }
}

推荐答案

令牌被拒绝的原因是因为它使用了错误的算法签名:你使用的是 HMAC-SHA256(一种对称密钥加密算法)，而正确的令牌使用 RSA-SHA256(一种非对称或公钥/私钥算法).您可以在示例令牌的标题中看到这一点:"alg": "RS256"

The reason why the token is being rejected is because it's signed using the wrong algorithm: you're using HMAC-SHA256 (a symmetric key encryption algorithm) while the correct token uses RSA-SHA256 (an asymmetric or public/private key algorithm). You can see this in the header of your example token: "alg": "RS256"

我建议使用 System.IdentityModel.Tokens.Jwt 中的类来大大简化您的代码:

I'd suggest using the classes in System.IdentityModel.Tokens.Jwt to simplify your code a lot:

public class GoogleJsonWebToken
{
    public static string Encode(string uid)
    {
        var firebaseInfPath = HttpContext.Current.Server.MapPath(WebConfigurationManager.AppSettings["firebaseInf"]);
        var firebaseInfJsonContent = File.ReadAllText(firebaseInfPath);
        var firebaseInf = JsonConvert.DeserializeObject<dynamic>(firebaseInfJsonContent);

        // NOTE: Replace this with your actual RSA public/private keypair!
        var provider = new RSACryptoServiceProvider(2048);
        var parameters = provider.ExportParameters(true);

        // Build the credentials used to sign the JWT
        var signingKey = new RsaSecurityKey(parameters);
        var signingCredentials = new SigningCredentials(signingKey, SecurityAlgorithms.RsaSha256);

        // Create a collection of optional claims
        var now = DateTimeOffset.UtcNow;
        var claims = new[]
        {
            new Claim(JwtRegisteredClaimNames.Sub, firebaseInf.client_email),
            new Claim(JwtRegisteredClaimNames.Iat, now.ToUnixTimeSeconds().ToString(), ClaimValueTypes.Integer64),
            new Claim("uid", uid, ClaimValueTypes.String), 
            new Claim("premium_account", "true", ClaimValueTypes.Boolean)
        };

        // Create and sign the JWT, and write it to a string
        var jwt = new JwtSecurityToken(
            issuer: firebaseInf.client_email,
            audience: "https://identitytoolkit.googleapis.com/google.identity.identitytoolkit.v1.IdentityToolkit",
            claims: claims,
            expires: now.AddMinutes(60).DateTime,
            signingCredentials: signingCredentials);
        return new JwtSecurityTokenHandler().WriteToken(jwt);
    }
}

使用虚拟密钥，此代码创建一个与示例令牌的标头和有效负载架构匹配的令牌:

Using a dummy key, this code creates a token that matches the header and payload schema of your example token:

eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJmaXJlYmFzZS1hdXRoLXRva2VuQHNheWVyLWNoYXQuaWFtLmdzZXJ2aWNlYWNjb3VudC5jb20iLCJpYXQiOjE0Njc4MzgwODUsInVpZCI6IjUyMTQiLCJwcmVtaXVtX2FjY291bnQiOnRydWUsImV4cCI6MTQ2Nzg2Njg4NSwiaXNzIjoiZmlyZWJhc2UtYXV0aC10b2tlbkBzYXllci1jaGF0LmlhbS5nc2VydmljZWFjY291bnQuY29tIiwiYXVkIjoiaHR0cHM6Ly9pZGVudGl0eXRvb2xraXQuZ29vZ2xlYXBpcy5jb20vZ29vZ2xlLmlkZW50aXR5LmlkZW50aXR5dG9vbGtpdC52MS5JZGVudGl0eVRvb2xraXQifQ.yMSGRpm4r3mPqiA9KnKVILVb8jT2Vbqcy4gvoLIugXnzLlw45F-GepAaBJK-J0-EN34WLsiLiLCRDJwW15TMasbrB1ZX3H4zd1by2GjZ1VmcUL8LITglICvs8CXkamjPjHeQUc4q - jhveKmTby8WHsH4b-HeiYoVl8JhxrAF13buNbiTq66dfvkl9q6mnyuKS_oyFB6_9WNphzHRa2BdJ51olq4qQsUNZ-nzOe4moHHjxpEzQfQpIe-QMJHdqojp9ukOW5eTMhFkQRPs3Bme4jpxIHPknC9j8YRvx_i0FbEJ8qAY2ujWcq80aC6YBKox55iP-AwfX_mEV7Tz14PBQ

eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJmaXJlYmFzZS1hdXRoLXRva2VuQHNheWVyLWNoYXQuaWFtLmdzZXJ2aWNlYWNjb3VudC5jb20iLCJpYXQiOjE0Njc4MzgwODUsInVpZCI6IjUyMTQiLCJwcmVtaXVtX2FjY291bnQiOnRydWUsImV4cCI6MTQ2Nzg2Njg4NSwiaXNzIjoiZmlyZWJhc2UtYXV0aC10b2tlbkBzYXllci1jaGF0LmlhbS5nc2VydmljZWFjY291bnQuY29tIiwiYXVkIjoiaHR0cHM6Ly9pZGVudGl0eXRvb2xraXQuZ29vZ2xlYXBpcy5jb20vZ29vZ2xlLmlkZW50aXR5LmlkZW50aXR5dG9vbGtpdC52MS5JZGVudGl0eVRvb2xraXQifQ.yMSGRpm4r3mPqiA9KnKVILVb8jT2Vbqcy4gvoLIugXnzLlw45F-GepAaBJK-j0-EN34WLsiLiLCRDJwW15TMasbrB1ZX3H4zd1by2GjZ1VmcUL8LITglICvs8CXkamjPjHeQUc4q--jhveKmTby8WHsH4b-HeiYoVl8JhxrAF13buNbiTq66dfvkl9q6mnyuKS_oyFB6_9WNphzHRa2BdJ51olq4qQsUNZ-nzOe4moHHjxpEzQfQpIe-QMJHdqojp9ukOW5eTMhFkQRPs3Bme4jpxIHPknC9j8YRvx_i0FbEJ8qAY2ujWcq80aC6YBKox55iP-AwfX_mEV7Tz14PBQ

您应该能够放入您的公钥/私钥对并使用上述代码生成有效的 JWT.

You should be able to drop in your public/private key pair and use the above code to generate valid JWTs.

这篇关于为 Firebase 生成 JWT的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持html5模板网！

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为 Firebase 生成 JWT

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