public byte[] DecryptDataWithSignature(EncryptedPacket EP, RsaWithRsaParameterKey rsaParams, DigitalSignatures DS)
{
// Receiver decrypts AES session key with RSA
byte[] decryptedSessionKey = rsaParams.DecryptData(EP.EncryptedSessionKey);
// Receiver compares
using (HMACSHA256 hmac = new HMACSHA256(decryptedSessionKey))
{
byte[] hmacToCheck = hmac.ComputeHash(EP.EncryptedData);
if (!CompareHashes(EP.Hmac, hmacToCheck))
{
throw new CryptographicException("HMAC for decryption does not match encrypted packet HMAC");
}
if (!DS.VerifySignature(EP.Hmac, EP.Signature))
{
throw new CryptographicException("Digital Signature cannot be verified");
}
}
// Receiver decrypts the data wuth AES using the decrypted session key
byte[] decryptedData = _cryptographyExample.DecryptUsingAES(EP.EncryptedData, decryptedSessionKey, EP.IV);
return(decryptedData);
}
public byte[] DecryptData(EncryptedPacket EP, RsaWithRsaParameterKey rsaParams)
{
// Receiver decrypts AES session key with RSA
byte[] decryptedSessionKey = rsaParams.DecryptData(EP.EncryptedSessionKey);
// Receiver decrypts the data wuth AES using the decrypted session key
byte[] decryptedData = _cryptographyExample.DecryptUsingAES(EP.EncryptedData, decryptedSessionKey, EP.IV);
return(decryptedData);
}