Manually decode OAuth bearer token in c#

Question

In my Web Api 2.2 OWIN based application I have a situation where I manually need to decode the bearer token but I don\'t know how to do this. This is my startup.cs

<         


        

Answer 1

You can read JWT and create Principals and Identity object using the System.IdentityModel.Tokens.Jwt package - https://www.nuget.org/packages/System.IdentityModel.Tokens.Jwt/.

Here's a quick example that shows the options available when reading and validating the token,

    private ClaimsIdentity GetIdentityFromToken(string token, X509Certificate2 certificate)
    {  
        var tokenDecoder = new JwtSecurityTokenHandler();         
        var jwtSecurityToken = (JwtSecurityToken)tokenDecoder.ReadToken(token);

        SecurityToken validatedToken;

        var principal = tokenDecoder.ValidateToken(
            jwtSecurityToken.RawData,
            new TokenValidationParameters()
                {
                    ValidateActor = false,
                    ValidateIssuer = false,
                    ValidateAudience = false,
                    ValidateLifetime = false,
                    ValidateIssuerSigningKey = false,
                    RequireExpirationTime = false,
                    RequireSignedTokens = false,
                    IssuerSigningToken = new X509SecurityToken(certificate)
                },
            out validatedToken);

        return principal.Identities.FirstOrDefault();
    }