public static async Task <TValue> Decrypt <TValue>(byte[] privateKey, EncryptedDataBlock dataBlock)
{
if (dataBlock == null)
{
throw new ArgumentNullException(nameof(dataBlock));
}
ValidateDigitalSignature(privateKey, dataBlock);
var decryptedValue = await SymmetricallyDecrypt(Convert.FromBase64String(dataBlock.AesKey),
Convert.FromBase64String(dataBlock.InitialisationVector), dataBlock.EncryptedData)
.ConfigureAwait(false);
return(JsonConvert.DeserializeObject <TValue>(decryptedValue));
}
private static void ValidateDigitalSignature(byte[] privateKey, EncryptedDataBlock dataBlock)
{
try
{
var decryptedDigitalSignature =
Convert.ToBase64String(AsymmetricallyDecrypt(privateKey, dataBlock.DigitalSignature));
var hash = Convert.ToBase64String(GenerateHash(Encoding.UTF8.GetBytes(dataBlock.EncryptedData)));
if (string.Compare(decryptedDigitalSignature, hash, StringComparison.OrdinalIgnoreCase) != 0)
{
throw new InvalidOperationException(
"The computed digital signature for the data block does not match the original digital signature.");
}
}
catch (CryptographicException ex)
{
throw new InvalidOperationException(
"There was a problem decrypting the data block. Potential data corruption or packet tampering has occurred.",
ex);
}
}
