public static JWTProperty JWTDecode(string jwt)
{
JWTProperty jwtProperty = new JWTProperty();
string[] tokens = jwt.Split('.');
if (tokens.Length != 3)
{
throw new ApplicationException("jwt separate error.");
}
string header = tokens[0];
string payload = tokens[1];
jwtProperty._signature = tokens[2];
jwtProperty._toSignatureString = header + "." + payload;
jwtProperty._header = Base64Decode(header);
jwtProperty._payload = Base64Decode(payload);
return jwtProperty;
}
public static JWTProperty JWTDecode(string jwt)
{
JWTProperty jwtProperty = new JWTProperty();
string[] tokens = jwt.Split('.');
if (tokens.Length != 3)
{
throw new ApplicationException("jwt separate error.");
}
string header = tokens[0];
string payload = tokens[1];
jwtProperty._signature = tokens[2];
jwtProperty._toSignatureString = header + "." + payload;
jwtProperty._header = Base64Decode(header);
jwtProperty._payload = Base64Decode(payload);
return(jwtProperty);
}
public static bool Validation(string idToken, string jwksJsonString)
{
// IDトークンはJWTなのでまず分解する。
JWTProperty jwtProperty = JWTDecode(idToken);
var idtokenHeader = JObject.Parse(jwtProperty._header);
var idtokenPayload = JObject.Parse(jwtProperty._payload);
// jwksのJSONをパースする
var json_jwks = JObject.Parse(jwksJsonString);
var keys = json_jwks["keys"];
string modulus = string.Empty;
string exponent = string.Empty;
string alg = string.Empty;
JArray a = JArray.Parse(keys.ToString());
foreach (JObject k in a.Children <JObject>())
{
if (idtokenHeader["kid"].ToString() == k["kid"].ToString())
{
modulus = k["n"].ToString();
exponent = k["e"].ToString();
alg = k["alg"].ToString();
}
}
bool b = false;
RSAParameters publicKeyParams = new RSAParameters();
publicKeyParams.Modulus = DecodeBytes(modulus);
publicKeyParams.Exponent = DecodeBytes(exponent);
RSACryptoServiceProvider publicKey = new RSACryptoServiceProvider();
publicKey.ImportParameters(publicKeyParams);
RSAPKCS1SignatureDeformatter rsaDeformatter = new RSAPKCS1SignatureDeformatter(publicKey);
//署名の検証に使用するハッシュアルゴリズムを指定
string hashAlgorithm = string.Empty;
string signstring = jwtProperty._toSignatureString;
byte[] hashData = null;
switch (alg)
{
case "RS256":
hashAlgorithm = "SHA256";
SHA256 signer_sha256 = SHA256.Create();
hashData = signer_sha256.ComputeHash(Encoding.UTF8.GetBytes(signstring));
break;
case "HS256":
hashAlgorithm = "HMACSHA256";
HMAC signer_hsha256 = HMACSHA256.Create();
hashData = signer_hsha256.ComputeHash(Encoding.UTF8.GetBytes(signstring));
break;
case "RS512":
hashAlgorithm = "SHA512";
SHA512 signer_sha512 = SHA512.Create();
hashData = signer_sha512.ComputeHash(Encoding.UTF8.GetBytes(signstring));
break;
}
rsaDeformatter.SetHashAlgorithm(hashAlgorithm);
//署名を検証し、結果を返す
b = rsaDeformatter.VerifySignature(hashData, DecodeBytes(jwtProperty._signature));
return(b);
}
