OAuth 无效的 Bas64

Question

我正在尝试实施 OAuth 流程，在我为客户提供的服务中，我有以下代码行：

services.AddAuthentication(config => {
            // We check the cookie to confirm that we are authenticated
            config.DefaultAuthenticateScheme = "ClientCookie";
            // When we sign in we will deal out a cookie
            config.DefaultSignInScheme = "ClientCookie";
            // use this to check if we are allowed to do something.
            config.DefaultChallengeScheme = "OurServer";
        })
            .AddCookie("ClientCookie")
            .AddOAuth("OurServer", config => {
                config.ClientId = "client_id";
                config.ClientSecret = "client_secret";
                config.CallbackPath = "/oauth/callback";
                config.AuthorizationEndpoint = "https://localhost:44360/oauth/authorize";
                config.TokenEndpoint = "https://localhost:44360/oauth/token";
                config.SaveTokens = true;

                config.Events = new OAuthEvents()
                {
                    OnCreatingTicket = context =>
                    {
                        var accessToken = context.AccessToken;
                        var base64payload = accessToken.Split('.')[1];
                        var modified = base64payload.Replace(" ", "");
                        var bytes = Convert.FromBase64String(base64payload);
                        var jsonPayload = Encoding.UTF8.GetString(bytes);
                        var claims = JsonConvert.DeserializeObject<Dictionary<string, string>>(jsonPayload);

                        foreach (var claim in claims)
                        {
                            context.Identity.AddClaim(new Claim(claim.Key, claim.Value));
                        }

                        return Task.CompletedTask;
                    }
                };
            });

当它尝试从其 base64 表示形式转换字符串时，它会抛出一个：System.FormatException: The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.

这让我感到困惑，因为我正在关注 YouTube 上的教程，据我所知，通过关注它并查看 github 代码是相同的。假定无效的 Base64 字符串是：

eyJzdWIiOiJzb21lX2lkIiwiR3Jhbm55IjoiQ29va2llIiwibmJmIjoxNjEwMTYwMjE5LCJleHAiOjE2MTAyNDY2MTksImlzcyI6Imh0dHA6Ly9sb2NhbGhvc3Q6NDQzNjAvIiwiYXVkIjoiaHR0cDovL2xvY2FsaG9zdDo0NDM2MC8ifQ

这很奇怪，因为检查 https://www.base64decode.org/ 正确 returns 以下内容：

{"sub":"some_id","Granny":"Cookie","nbf":1610160219,"exp":1610246619,"iss":"http://localhost:44360/","aud":"http://localhost:44360/"}

这似乎是有效的，因为它与我在服务器端的控制器中设置的 JWT 令牌的声明和内容相匹配。我到底做错了什么？我检查了其他处理令牌问题的地方，但没有看到任何无效字符，例如 -、+ 等。

编辑：

解决方法是执行以下操作，感谢 LinkedListT 提到它不是 4 的倍数。

private string AddPaddingToBase64(string base64)
        {
            if(base64.Length % 4 == 0) 
                return base64;
            else
            {
                var builder = new StringBuilder(base64);
                builder.Append("=");
                return AddPaddingToBase64(builder.ToString());
            } 

        }

然后我们首先解析字符串的地方让它通过该方法，然后将修改后的 base64 传递给转换器。这也是 3 年多专业开发中递归实际上比迭代更简单直接的第一次。

Answer 1

问题是您的 base64 字符串无效。

The length of a base64 encoded string is always a multiple of 4. If it is not a multiple of 4, then = characters are appended until it is. A query string of the form ?name=value has problems when the value contains = characters (some of them will be dropped, I don't recall the exact behavior). You may be able to get away with appending the right number of = characters before doing the base64 decode.

因此您需要将“==”附加到相关的 base64 字符串。即

Convert.FromBase64String("eyJzdWIiOiJzb21lX2lkIiwiR3Jhbm55IjoiQ29va2llIiwibmJmIjoxNjEwMTYwMjE5LCJleHAiOjE2MTAyNDY2MTksImlzcyI6Imh0dHA6Ly9sb2NhbGhvc3Q6NDQzNjAvIiwiYXVkIjoiaHR0cDovL2xvY2FsaG9zdDo0NDM2MC8ifQ==");

OAuth 无效的 Bas64

OAuth Invalid Bas64

c#

oauth

jwt