我正在尝试为 Windows 上的 C# .NET 编写自定义 JWT token 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来源(我试图重新发现它们,以便我可以相信原始作者并提出一些额外的问题),所以它有点像大杂烩。
在大多数情况下,它似乎有效,但似乎没有按预期生成有效的(firebase) token 。这可能完全是因为我一开始对它应该如何工作缺乏了解,但是如果我能从这里得到第二双世界级的出色工程师的眼睛来指出我做错了什么并让事情发挥作用,那就太好了。
这是代码:
// 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);
}
}
}
这是 JWT 哈希算法代码:
// 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;
}
}
}
最佳答案
token 被拒绝的原因是它使用错误的算法签名:您使用的是 HMAC-SHA256(对称 key 加密算法),而正确的 token 使用 RSA-SHA256(非对称或公钥/私钥算法)。您可以在示例 token 的标题中看到这一点:"alg": "RS256"
我建议使用 System.IdentityModel.Tokens.Jwt
中的类来简化您的代码:
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 key ,此代码创建一个与示例 token 的 header 和有效负载架构相匹配的 token :
您应该能够放入您的公钥/私钥对并使用上面的代码生成有效的 JWT。
关于c# - 为 Firebase 生成 JWT,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/38230779/