Azure B2C : Generating the code_challenge

Question

我的 Azure 应用程序是单页应用程序，当尝试通过邀请实现电子邮件注册时，我收到错误:

AADB2C99059: The supplied request must present a code_challenge

我们的应用程序服务器是否会生成此 code_challenge，还是 Azure B2C 应该为我们执行此操作？另外，我们到底应该如何生成code_challenge？

Answer 1

您需要通过代码生成 code_challenge 并将其传递到请求 URL，并在获取访问 token 时使用 code_verifier。

引用 - https://medium.com/the-new-control-plane/using-proof-key-for-code-exchange-pkce-in-azure-ad-b2c-9203fbc148fd

C# 示例:

using IdentityModel;
using System;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
 
namespace PKCEConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            var random = new Random();
            int cvlength = random.Next(43, 128);
            const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~";
            var codeVerifier = new string (Enumerable.Repeat(chars, cvlength).Select(s => s[random.Next(s.Length)]).ToArray());
 
            string codeChallenge;
            using (var sha256 = SHA256.Create())
            {
                var a = Encoding.UTF8.GetBytes(codeVerifier);
                var challengeBytes = sha256.ComputeHash(Encoding.UTF8.GetBytes(codeVerifier));
                codeChallenge = Base64Url.Encode(challengeBytes);
 
/* Alternatively instead of using Base64Url.Encode method, the code below can accomplish the same result:
 
                var result = Convert.ToBase64String(challengeBytes)
                    .Replace('+', '-') // replace URL unsafe characters with safe ones
                    .Replace('/', '_') // replace URL unsafe characters with safe ones
                    .Replace("=", ""); // no padding
*/
            }
 
            Console.WriteLine("codeVerifier " + codeVerifier + "\n");
            Console.WriteLine("codeChallenge " + codeChallenge + "\n");
 
            Console.ReadLine();
        }
    }
}