public void VerifyMissionDetails()
{
MissionDetails missionDetails = GetMissionDetails();
VerifySignature(missionDetails);
string decryptedMessage = DecryptKey(missionDetails);
DecryptedMessageResponse = GetResponse(decryptedMessage);
}
private void VerifySignature(MissionDetails missionDetails)
{
byte[] encryptedMessage = missionDetails.EncryptedMessage.FromBase64();
SHA256 sha = SHA256.Create();
byte[] hash = sha.ComputeHash(encryptedMessage);
string xml = File.ReadAllText("ACMEpublickey.xml");
RSA rsa = RSA.Create(2048);
rsa.FromXmlString(xml);
AcmePublicKey = rsa.ExportParameters(false);
bool result = rsa.VerifyHash(hash, missionDetails.Signature.FromBase64(), HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
if (result == false)
{
throw new Exception("Failed Signature");
}
}
private string DecryptKey(MissionDetails missionDetails)
{
byte[] encryptedkey = missionDetails.EncryptedKey.FromBase64();
byte[] decryptedkey;
using (RSA rsa = RSA.Create())
{
rsa.ImportParameters(MyPrivateKey);
decryptedkey = rsa.Decrypt(encryptedkey, RSAEncryptionPadding.Pkcs1);
}
Aes aes = Aes.Create();
aes.Key = decryptedkey;
aes.IV = missionDetails.IV.FromBase64();
ICryptoTransform decryptor = aes.CreateDecryptor();
byte[] decryptedMessageBytes;
using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, decryptor, CryptoStreamMode.Write))
{
byte[] encryptedMissionBytes = missionDetails.EncryptedMessage.FromBase64();
cs.Write(encryptedMissionBytes, 0, encryptedMissionBytes.Length);
}
decryptedMessageBytes = ms.ToArray();
}
string decryptedMessage = decryptedMessageBytes.GetString();
VerifyMissionString(decryptedMessage, missionDetails.MissionHash);
return(decryptedMessage);
}