private static async Task DecryptContentAsync(Stream source, Stream destination, int recordSize, byte[] contentEncryptionKeyInfoParameterHash, byte[] nonceInfoParameterHash)
{
using (Aes128GcmCipher aes128GcmCipher = new Aes128GcmCipher(contentEncryptionKeyInfoParameterHash, nonceInfoParameterHash))
{
int maxPlainTextLength = recordSize - RECORD_ENCRYPTION_OVERHEAD_SIZE - RECORD_DELIMITER_SIZE;
byte[] plainTextBuffer = _arrayPool.Rent(maxPlainTextLength + RECORD_DELIMITER_SIZE);
byte[] cipherTextBuffer = _arrayPool.Rent(recordSize);
try
{
int recordDelimiterIndex = 0;
ulong recordSequenceNumber = 0;
do
{
int cipherTextLength = await source.ReadAsync(cipherTextBuffer, 0, recordSize).ConfigureAwait(false);
if (cipherTextLength == 0)
{
ThrowInvalidOrderOrMissingRecordException();
}
int plainTextLength = aes128GcmCipher.Decrypt(cipherTextBuffer, cipherTextLength, plainTextBuffer, recordSequenceNumber++);
recordDelimiterIndex = GetRecordDelimiterIndex(plainTextBuffer, plainTextLength, maxPlainTextLength);
if ((plainTextBuffer[recordDelimiterIndex] == LAST_RECORD_DELIMITER) && (source.ReadByte() != -1))
{
ThrowInvalidOrderOrMissingRecordException();
}
await destination.WriteAsync(plainTextBuffer, 0, recordDelimiterIndex).ConfigureAwait(false);
}while (plainTextBuffer[recordDelimiterIndex] != LAST_RECORD_DELIMITER);
}
finally
{
_arrayPool.Return(plainTextBuffer, true);
_arrayPool.Return(cipherTextBuffer, true);
}
}
}
private static async Task EncryptContentAsync(Stream source, Stream destination, int recordSize, byte[] contentEncryptionKeyInfoParameterHash, byte[] nonceInfoParameterHash)
{
using (Aes128GcmCipher aes128GcmCipher = new Aes128GcmCipher(contentEncryptionKeyInfoParameterHash, nonceInfoParameterHash))
{
int maxPlainTextLength = recordSize - RECORD_ENCRYPTION_OVERHEAD_SIZE - RECORD_DELIMITER_SIZE;
byte[] plainTextBuffer = _arrayPool.Rent(maxPlainTextLength + RECORD_DELIMITER_SIZE);
byte[] cipherTextBuffer = _arrayPool.Rent(recordSize);
try
{
int plainTextLength;
int?peekedPlainTextByte = null;
ulong recordSequenceNumber = 0;
do
{
plainTextLength = await GetPlainTextAsync(source, plainTextBuffer, maxPlainTextLength, (byte?)peekedPlainTextByte).ConfigureAwait(false);
if (plainTextBuffer[plainTextLength - 1] != LAST_RECORD_DELIMITER)
{
peekedPlainTextByte = source.ReadByte();
if (peekedPlainTextByte == -1)
{
plainTextBuffer[plainTextLength - 1] = LAST_RECORD_DELIMITER;
}
}
int cipherTextLength = aes128GcmCipher.Encrypt(plainTextBuffer, plainTextLength, cipherTextBuffer, recordSequenceNumber++);
await destination.WriteAsync(cipherTextBuffer, 0, cipherTextLength).ConfigureAwait(false);
}while (plainTextBuffer[plainTextLength - 1] != LAST_RECORD_DELIMITER);
}
finally
{
_arrayPool.Return(plainTextBuffer, true);
_arrayPool.Return(cipherTextBuffer, true);
}
}
}
