How to generate JWT Token with IdentityModel Extensions for .NET 5

Question

I am using IdentityModel Extensions for .NET version 4 to generate JWT token with symmetric key and SHA256 as below and it works perfectly:

var tokenDescriptor = new SecurityTokenDescriptor
{
    Subject = new ClaimsIdentity(claims),

    TokenIssuerName = Issuer,
    AppliesToAddress = Audience,

    Lifetime = new Lifetime(now, expirationTime),

    SigningCredentials = new SigningCredentials(
        new InMemorySymmetricSecurityKey(symmetricKey),
        "http://www.w3.org/2001/04/xmldsig-more#hmac-sha256",
        "http://www.w3.org/2001/04/xmlenc#sha256"),
};

var securityToken = tokenHandler.CreateToken(tokenDescriptor);
var token = tokenHandler.WriteToken(securitytoken);

But when I tried to upgrade to IdentityModel Extensions for .NET 5 as below code:

var tokenDescriptor = new SecurityTokenDescriptor
{
    Subject = new ClaimsIdentity(claims),

    Issuer = Issuer,
    Audience = Audience,

    Expires = expirationTime,
    SigningCredentials = new SigningCredentials(
        new SymmetricSecurityKey(symmetricKey), "SHA256")
};

var securityToken = tokenHandler.CreateToken(tokenDescriptor);
var token = tokenHandler.WriteToken(stoken);

I got exception:

IDX10634: Unable to create the SignatureProvider.

SignatureAlgorithm: 'SHA256', SecurityKey: 'Microsoft.IdentityModel.Tokens.SymmetricSecurityKey' is not supported.

What's wrong with the new code using version 5.

Answer 1

They've changed their implementation a little bit, so

change

SigningCredentials = new SigningCredentials(
    new SymmetricSecurityKey(symmetricKey), "SHA256")

to

SigningCredentials = new SigningCredentials(
    new SymmetricSecurityKey(symmetricKey), Microsoft.IdentityModel.Tokens.SecurityAlgorithms.HmacSha256Signature)

Answer 2

Here is the solution, it's working

using Microsoft.IdentityModel.Tokens;   
using System;   
using System.IdentityModel.Tokens.Jwt;   
using System.Security.Claims; 

using System.Security.Cryptography;   
using System.Security.Cryptography.X509Certificates;  
using System.Text;

namespace ConsoleApplication2
{ 

private class JWT
{
private bool verbose = false;
public  string GenerateJWT()
{
    DateTime UnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);

    RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
    // Provide proper private key
    string privateSecretKey = "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";

    rsa = DecodeRSAPrivateKey(FromBase64Url(privateSecretKey));
    //convert to csp format
    var bytes = rsa.ExportCspBlob(false);
    var publicKey = Convert.ToBase64String(bytes);
    //

    RsaSecurityKey _signingKey = new RsaSecurityKey(rsa);
    Microsoft.IdentityModel.Tokens.SigningCredentials signingCredentials =
           new Microsoft.IdentityModel.Tokens.SigningCredentials(_signingKey, SecurityAlgorithms.RsaSha256);

    JwtHeader head = new JwtHeader(signingCredentials);
    head.Add("kid", "lzo-firstpublickey");


    string sNewGuid = Guid.NewGuid().ToString("n");

    var claims = new[]
          {
              new Claim(JwtRegisteredClaimNames.Iss, "s6BhdRkqt3"),
              new Claim(JwtRegisteredClaimNames.Sub, "s6BhdRkqt3"),
              new Claim(JwtRegisteredClaimNames.Aud, "https://cis.ncrs/connect/token"),
              new Claim(JwtRegisteredClaimNames.Jti,  sNewGuid),
              new Claim(JwtRegisteredClaimNames.Exp, ((Int64)DateTime.Now.AddMinutes(55).Subtract(UnixEpoch).TotalSeconds).ToString(System.Globalization.CultureInfo.InvariantCulture), ClaimValueTypes.Integer64),
              new Claim(JwtRegisteredClaimNames.Iat, ((Int64)DateTime.Now.Subtract(UnixEpoch).TotalSeconds).ToString(System.Globalization.CultureInfo.InvariantCulture), ClaimValueTypes.Integer64)
          };


    JwtPayload payload = new JwtPayload(claims);
    JwtSecurityToken jwt = new JwtSecurityToken(head, payload);
    jwt.SigningKey = _signingKey;
    var encodedJwt = new JwtSecurityTokenHandler().WriteToken(jwt);
    return encodedJwt;
}

private static byte[] FromBase64Url(string base64Url)
{
    string base64 = string.Empty;
    if (!string.IsNullOrEmpty(base64Url))
    {
        string padded = base64Url.Length % 4 == 0
            ? base64Url : base64Url + "====".Substring(base64Url.Length % 4);
        base64 = padded.Replace("_", "/")
                                .Replace("-", "+");
    }
    return Convert.FromBase64String(base64);
}


private RSACryptoServiceProvider DecodeRSAPrivateKey(byte[] privkey)
{
    byte[] MODULUS, E, D, P, Q, DP, DQ, IQ;

    // ---------  Set up stream to decode the asn.1 encoded RSA private key  ------
    System.IO.MemoryStream mem = new System.IO.MemoryStream(privkey);
    System.IO.BinaryReader binr = new System.IO.BinaryReader(mem);    //wrap Memory Stream with BinaryReader for easy reading
    byte bt = 0;
    ushort twobytes = 0;
    int elems = 0;
    try
    {
        twobytes = binr.ReadUInt16();
        if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)
            binr.ReadByte();        //advance 1 byte
        else if (twobytes == 0x8230)
            binr.ReadInt16();       //advance 2 bytes
        else
            return null;

        twobytes = binr.ReadUInt16();
        if (twobytes != 0x0102) //version number
            return null;
        bt = binr.ReadByte();
        if (bt != 0x00)
            return null;


        //------  all private key components are Integer sequences ----
        elems = GetIntegerSize(binr);
        MODULUS = binr.ReadBytes(elems);

        elems = GetIntegerSize(binr);
        E = binr.ReadBytes(elems);

        elems = GetIntegerSize(binr);
        D = binr.ReadBytes(elems);

        elems = GetIntegerSize(binr);
        P = binr.ReadBytes(elems);

        elems = GetIntegerSize(binr);
        Q = binr.ReadBytes(elems);

        elems = GetIntegerSize(binr);
        DP = binr.ReadBytes(elems);

        elems = GetIntegerSize(binr);
        DQ = binr.ReadBytes(elems);

        elems = GetIntegerSize(binr);
        IQ = binr.ReadBytes(elems);

        Console.WriteLine("showing components ..");
        if (verbose)
        {
            showBytes("\nModulus", MODULUS);
            showBytes("\nExponent", E);
            showBytes("\nD", D);
            showBytes("\nP", P);
            showBytes("\nQ", Q);
            showBytes("\nDP", DP);
            showBytes("\nDQ", DQ);
            showBytes("\nIQ", IQ);
        }

        // ------- create RSACryptoServiceProvider instance and initialize with public key -----
        RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
        RSAParameters RSAparams = new RSAParameters();
        RSAparams.Modulus = MODULUS;
        RSAparams.Exponent = E;
        RSAparams.D = D;
        RSAparams.P = P;
        RSAparams.Q = Q;
        RSAparams.DP = DP;
        RSAparams.DQ = DQ;
        RSAparams.InverseQ = IQ;
        RSA.ImportParameters(RSAparams);
        return RSA;
    }
    catch (Exception)
    {
        return null;
    }
    finally
    {
        binr.Close();
    }
}

private void showBytes(String info, byte[] data)
{
    Console.WriteLine("{0}  [{1} bytes]", info, data.Length);
    for (int i = 1; i <= data.Length; i++)
    {
        Console.Write("{0:X2}  ", data[i - 1]);
        if (i % 16 == 0)
            Console.WriteLine();
    }
    Console.WriteLine("\n\n");
}

private int GetIntegerSize(System.IO.BinaryReader binr)
{
    byte bt = 0;
    byte lowbyte = 0x00;
    byte highbyte = 0x00;
    int count = 0;
    bt = binr.ReadByte();
    if (bt != 0x02)     //expect integer
        return 0;
    bt = binr.ReadByte();

    if (bt == 0x81)
        count = binr.ReadByte();    // data size in next byte
    else
        if (bt == 0x82)
        {
            highbyte = binr.ReadByte(); // data size in next 2 bytes
            lowbyte = binr.ReadByte();
            byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };
            count = BitConverter.ToInt32(modint, 0);
        }
        else
        {
            count = bt;     // we already have the data size
        }



    while (binr.ReadByte() == 0x00)
    {   //remove high order zeros in data
        count -= 1;
    }
    binr.BaseStream.Seek(-1, System.IO.SeekOrigin.Current);     //last     ReadByte wasn't a removed zero, so back up a byte
    return count;
}
}
}