public JToken DecryptResourceData(JToken item)
{
const string encryptedContentProperty = "encryptedContent";
const string certificateIdProperty = "encryptionCertificateId";
const string symmetricKeyProperty = "dataKey";
const string encryptedPayloadProperty = "data";
const string signatureProperty = "dataSignature";
var encryptedContent = item[encryptedContentProperty];
string certificateId = encryptedContent[certificateIdProperty]?.Value <string>() ?? throw new InvalidOperationException("Encryption key id does not exist in the notification payload");
string encryptedSymmetricKey = encryptedContent[symmetricKeyProperty]?.Value <string>() ?? throw new InvalidOperationException("Symmetric key does not exist in the notification payload");
string encryptedPayload = encryptedContent[encryptedPayloadProperty]?.Value <string>() ?? throw new InvalidOperationException("Encrypted payload ;sdoes not exist in the notification payload");
string hashMac = encryptedContent[signatureProperty]?.Value <string>() ?? throw new InvalidOperationException("Encrypted signature does not exist in the notification payload");
var payloadBytes = Convert.FromBase64String(encryptedPayload);
var signatureBytes = Convert.FromBase64String(hashMac);
// descrypt the symetric key
var symmetricKey = AsymmetricDecryptor.Decrypt(Convert.FromBase64String(encryptedSymmetricKey), certificateId);
// verify signature using the symmetric key
SymmetricDecryptor.VerifyHMACSignature(payloadBytes, symmetricKey, signatureBytes);
// decrypt payload using symmetric key
string plainText = SymmetricDecryptor.Decrypt(payloadBytes, symmetricKey);
return(JToken.Parse(plainText));
}
public static byte[] AsymmetricDecrypt(
RSACryptoServiceProvider rsa, byte[] data)
{
if (rsa == null)
{
throw new ArgumentNullException("rsa");
}
if (data == null)
{
throw new ArgumentNullException("data");
}
AsymmetricDecryptor decryptor = new AsymmetricDecryptor(rsa, data);
return(decryptor.GetDecryptedBytes());
}
public void TestAsymmetricDecryption()
{
var someBytes = new byte[32];
new Random().NextBytes(someBytes);
const string certId = "E96149FC-3B4F-4E0B-ACED-E715D29961FD";
var key = Convert.FromBase64String(DummyKeyStore.GetPublicKeyLocal(certId));
var cert = new X509Certificate2();
cert.Import(key);
byte[] encryptedBytes;
using (var provider = (RSACryptoServiceProvider)cert.PublicKey.Key)
{
encryptedBytes = provider.Encrypt(someBytes, true);
}
var decryptedBytes = AsymmetricDecryptor.Decrypt(encryptedBytes, certId);
Assert.IsTrue(someBytes.SequenceEqual(decryptedBytes));
}
