Ignore JWT Bearer token signature (i.e. don't validate token)

Try this. Finally, I got it to work after so much of trying.

public TokenValidationParameters CreateTokenValidationParameters()
{
    var result = new TokenValidationParameters
    {
    ValidateIssuer = false,
    ValidIssuer = ValidIssuer,

    ValidateAudience = false,
    ValidAudience = ValidAudience,

    ValidateIssuerSigningKey = false,
    //IssuerSigningKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(SecretKey)),
    //comment this and add this line to fool the validation logic
    SignatureValidator = delegate(string token, TokenValidationParameters parameters)
    {
        var jwt = new JwtSecurityToken(token);

        return jwt;
    },

    RequireExpirationTime = true,
    ValidateLifetime = true,

    ClockSkew = TimeSpan.Zero,
    };

    result.RequireSignedTokens = false;

    return result;
}

You may setup token validation using JwtBearerOptions.TokenValidationParameters. You could check all available parameters from the class definition.

Contains a set of parameters that are used by a Microsoft.IdentityModel.Tokens.SecurityTokenHandler when validating a Microsoft.IdentityModel.Tokens.SecurityToken.

Set All ValidateXXX and RequireXXX bool properties to false if you want to disable validation at all:

.AddJwtBearer("<authenticationScheme>", configureOptions =>
{
   options.TokenValidationParameters.ValidateActor = false;
   options.TokenValidationParameters.ValidateAudience = false;
   options.TokenValidationParameters.ValidateIssuerSigningKey = false;
   ...
}

---

As an another option you can override the default token signature validation by setting own implementation to JwtBearerOptions.SignatureValidator:

// Gets or sets a delegate that will be used to validate the signature of the token.
//
// Remarks:
//  If set, this delegate will be called to signature of the token, instead of normal
//  processing.
public SignatureValidator SignatureValidator { get; set; }

where SignatureValidator delegate is defined as:

public delegate SecurityToken SignatureValidator(string token, TokenValidationParameters validationParameters);