/// <summary>
/// This constructor should be used to load and incoming token.
/// </summary>
/// <param name="token">The compact serialized token.</param>
/// <param name="secret">The secret to validate the token.</param>
/// <param name="validateSignature">A boolean value that indicates when token should be validated with the secret.</param>
/// <param name="supportNoneAlgo">This property specifies whether the none algorithm should be supported. As this is a security risk, it has to be explicitly set to accept.</param>
public JwtToken(string token, byte[] secret, bool validateSignature = true, bool supportNoneAlgo = false)
{
mIncoming = new JwtRoot(token);
Header = new JOSEHeader(mIncoming.JoseHeader);
if (!string.Equals(Header.Type, "JWT", StringComparison.InvariantCultureIgnoreCase))
{
throw new JwtTokenStructureInvalidException("The JWT declaration is not in the JOSE Header");
}
//Check that the algorithm is supported.
var algo = Header.SupportedAlgorithm;
if (algo == JwtHashAlgorithm.None && !supportNoneAlgo)
{
throw new JwtAlgorithmNoneNotAllowedException();
}
Claims = new JwtClaims(JwtRoot.UTF8ToJSONConvert(mIncoming.Raw[1]));
if (validateSignature && !JwtValidateIncoming(mIncoming, algo, secret))
{
throw new JwtSignatureInvalidException();
}
}
/// <summary>
/// This method signs the token and returns it using JWS Compact Serialization notation.
/// </summary>
/// <param name="key">The key.</param>
/// <returns>Returns a compact serialization key.</returns>
public string ToString(byte[] key)
{
JwtHashAlgorithm algo = Header.SupportedAlgorithm;
string b64joseHeader = JwtHelper.SafeBase64UrlEncode(Encoding.UTF8.GetBytes(Header.ToString()));
string b64jwtClaimsSet = JwtHelper.SafeBase64UrlEncode(Encoding.UTF8.GetBytes(Claims.ToString()));
string signature = JwtRoot.CalculateAuthSignature(algo, key, b64joseHeader, b64jwtClaimsSet);
return($"{b64joseHeader}.{b64jwtClaimsSet}.{signature}");
}
private bool JwtValidateIncoming(JwtRoot incoming, JwtHashAlgorithm algo, byte[] key)
{
if (incoming == null)
{
throw new ArgumentOutOfRangeException("Incoming token not set.");
}
if (key == null)
{
throw new ArgumentNullException("key", $"{nameof(JwtValidateIncoming)} - key cannot be null");
}
string b64joseHeader = JwtHelper.SafeBase64UrlEncode(incoming.Raw[0]);
string b64jwtClaimsSet = JwtHelper.SafeBase64UrlEncode(incoming.Raw[1]);
var signed = JwtRoot.CalculateAuthSignature(algo, key, b64joseHeader, b64jwtClaimsSet);
var original = JwtHelper.SafeBase64UrlEncode(incoming.Raw[2]);
return(original == signed);
}
