How to decode JWT Token

Question

I don t understand how this library works  Could you help me please    Here is my simple code    public void TestJwtSecurityTokenHandler                 var stream                eyJhbGciOiJSUzI1NiJ9 eyJpc3MiOiJJU1MiLCJzY29wZSI6Imh0dHBzOi8vbGFyaW0uZG5zY2UuZG91YW5lL2NpZWxzZXJ2aWNlL3dzIiwiYXVkIjoiaHR0cHM6Ly9kb3VhbmUuZmluYW5jZXMuZ291di5mci9vYXV0aDIvdjEiLCJpYXQiOiJcL0RhdGUoMTQ2ODM2MjU5Mzc4NClcLyJ9           var handler   new JwtSecurityTokenHandler             var jsonToken   handler ReadToken stream           This is the error       The string needs to be in compact JSON format  which is of the form  Base64UrlEncodedHeader Base64UrlEndcodedPayload OPTIONAL Base64UrlEncodedSignature     If you copy the stream in jwt io website  it works fine

User · Answer

var key   new SymmetricSecurityKey Encoding UTF8 GetBytes  config  quot Jwt Key quot        var creds   new SigningCredentials key  SecurityAlgorithms HmacSha256     var claims   new             new Claim JwtRegisteredClaimNames Email  model UserName         new Claim JwtRegisteredClaimNames NameId  model Id ToString            var token   new JwtSecurityToken  config  quot Jwt Issuer quot           config  quot Jwt Issuer quot          claims        expires  DateTime Now AddMinutes 30         signingCredentials  creds    Then extract content  var handler   new JwtSecurityTokenHandler     string authHeader   Request Headers  quot Authorization quot     authHeader   authHeader Replace  quot Bearer  quot    quot  quot     var jsonToken   handler ReadToken authHeader    var tokenS   handler ReadToken authHeader  as JwtSecurityToken   var id   tokenS Claims First claim   gt  claim Type     quot nameid quot   Value

User · Answer

I found the solution  I just forgot to Cast the result     var stream    encoded jwt      var handler   new JwtSecurityTokenHandler    var jsonToken   handler ReadToken stream   var tokenS   handler ReadToken stream  as JwtSecurityToken    I can get Claims using   var jti   tokenS Claims First claim   gt  claim Type     jti   Value

User · Answer

new JwtSecurityTokenHandler   ReadToken     will return a SecurityToken  new JwtSecurityTokenHandler   ReadJwtToken     will return a JwtSecurityToken  If you just change the method you are using you can avoid the cast in the above answer

User · Answer

Using  net core jwt packages  the Claims are available    Route  api  controller      ApiController   Authorize Policy    Bearer    public class AbstractController  ControllerBase       protected string UserId                 var principal   HttpContext User          if  principal  Claims    null                        foreach  var claim in principal Claims                               log Debug   CLAIM TYPE   claim Type   CLAIM VALUE   claim Value                                      return principal  Claims  SingleOrDefault p   gt  p Type     username    Value

User · Answer

Extending on cooxkie answer  and dpix answer  when you are reading a jwt token  such as an access token received from AD FS   you can merge the claims in the jwt token  with the claims from  context AuthenticationTicket Identity  that might not have the same set of claims as the jwt token    To Illustrate  in an Authentication Code flow using OpenID Connect after a user is authenticated  you can handle the event SecurityTokenValidated which provides you with an authentication context  then you can use it to read the access token as a jwt token  then you can  merge  tokens that are in the access token with the standard list of claims received as part of the user identity       private Task OnSecurityTokenValidated SecurityTokenValidatedNotification lt OpenIdConnectMessage OpenIdConnectAuthenticationOptions gt  context                  get the current user identity         ClaimsIdentity claimsIdentity    ClaimsIdentity context AuthenticationTicket Identity             read access token from the current context           string access token   context ProtocolMessage AccessToken           JwtSecurityTokenHandler hand   new JwtSecurityTokenHandler              read the token as recommended by Coxkie and dpix         var tokenS   hand ReadJwtToken access token             here  you read the claims from the access token which might have            additional claims needed by your application         foreach  var claim in tokenS Claims                        if   claimsIdentity HasClaim claim Type  claim Value                   claimsIdentity AddClaim claim                      return Task FromResult 0

User · Answer

You need the secret string which was used to generate encrypt token   This code works for me   protected string GetName string token                string secret    this is a string used for encrypt and decrypt token            var key   Encoding ASCII GetBytes secret           var handler   new JwtSecurityTokenHandler            var validations   new TokenValidationParameters                       ValidateIssuerSigningKey   true              IssuerSigningKey   new SymmetricSecurityKey key               ValidateIssuer   false              ValidateAudience   false                    var claims   handler ValidateToken token  validations  out var tokenSecure           return claims Identity Name

[c#] How to decode JWT Token?

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