要解决ASP.NET拒绝使用jsonwebtoken生成的JWT的问题，您可以使用System.IdentityModel.Tokens.Jwt库来生成JWT。下面是一个代码示例来生成JWT：

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

public class JwtTokenGenerator
{
    public string GenerateJwtToken(string secretKey, string issuer, string audience, string username, int expireMinutes = 60)
    {
        var securityKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(secretKey));
        var credentials = new SigningCredentials(securityKey, SecurityAlgorithms.HmacSha256);

        var claims = new[]
        {
            new Claim(JwtRegisteredClaimNames.Sub, username),
            new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString())
        };

        var token = new JwtSecurityToken(
            issuer: issuer,
            audience: audience,
            claims: claims,
            expires: DateTime.UtcNow.AddMinutes(expireMinutes),
            signingCredentials: credentials
        );

        return new JwtSecurityTokenHandler().WriteToken(token);
    }
}

使用示例：

string secretKey = "YourSecretKey";
string issuer = "YourIssuer";
string audience = "YourAudience";
string username = "JohnDoe";

JwtTokenGenerator tokenGenerator = new JwtTokenGenerator();
string jwtToken = tokenGenerator.GenerateJwtToken(secretKey, issuer, audience, username);

Console.WriteLine(jwtToken);

请替换"YourSecretKey"、"YourIssuer"、"YourAudience"为您自己的值，并根据您的需要调整expireMinutes的值。