public async Task <byte[]> ValidateAndDecrypt(EncryptThenMacData encryptThenMacData)
{
byte[] data = Convert.FromBase64String(encryptThenMacData.Data);
byte[] hmac = Convert.FromBase64String(encryptThenMacData.Hmac);
if (!await _hmacService.IsValid(hmac, data))
{
throw new Exception("HMAC is not valid.");
}
AesEncryptedData aesEncryptedData = _serializationService.DeserializeFromBytes <AesEncryptedData>(data);
return(await _aesEncryptionService.Decrypt(aesEncryptedData));
}
public async Task <EncryptThenMacData> EncryptThenMac(byte[] data)
{
AesEncryptedData aesEncryptedData = await _aesEncryptionService.Encrypt(data);
byte[] serializedAesEncryptedData = _serializationService.SerializeToBytes(aesEncryptedData);
byte[] hmac = await _hmacService.Generate(serializedAesEncryptedData);
return(new EncryptThenMacData()
{
Data = Convert.ToBase64String(serializedAesEncryptedData),
Hmac = Convert.ToBase64String(hmac)
});
}
public Task <byte[]> Decrypt(AesEncryptedData aesEncryptedData)
{
return(Task.FromResult(
XorCipher(aesEncryptedData.EncryptedData, aesEncryptedData.Iv)
));
}