size_t StreamTransformationFilter::LastBlockSize(StreamTransformation &c, BlockPaddingScheme padding)
{
if (c.MinLastBlockSize() > 0)
return c.MinLastBlockSize();
else if (c.MandatoryBlockSize() > 1 && !c.IsForwardTransformation() && padding != NO_PADDING && padding != ZEROS_PADDING)
return c.MandatoryBlockSize();
else
return 0;
}
StreamTransformationFilter::StreamTransformationFilter(StreamTransformation &c, BufferedTransformation *attachment, BlockPaddingScheme padding, bool allowAuthenticatedSymmetricCipher)
: FilterWithBufferedInput(attachment)
, m_cipher(c), m_padding(DEFAULT_PADDING), m_optimalBufferSize(0)
{
assert(c.MinLastBlockSize() == 0 || c.MinLastBlockSize() > c.MandatoryBlockSize());
if (!allowAuthenticatedSymmetricCipher && dynamic_cast<AuthenticatedSymmetricCipher *>(&c) != 0)
throw InvalidArgument("StreamTransformationFilter: please use AuthenticatedEncryptionFilter and AuthenticatedDecryptionFilter for AuthenticatedSymmetricCipher");
IsolatedInitialize(MakeParameters(Name::BlockPaddingScheme(), padding));
}
StreamTransformationFilter::StreamTransformationFilter(StreamTransformation &c, BufferedTransformation *attachment, BlockPaddingScheme padding)
: FilterWithBufferedInput(0, c.MandatoryBlockSize(), LastBlockSize(c, padding), attachment)
, m_cipher(c)
{
assert(c.MinLastBlockSize() == 0 || c.MinLastBlockSize() > c.MandatoryBlockSize());
bool isBlockCipher = (c.MandatoryBlockSize() > 1 && c.MinLastBlockSize() == 0);
if (padding == DEFAULT_PADDING)
{
if (isBlockCipher)
m_padding = PKCS_PADDING;
else
m_padding = NO_PADDING;
}
else
m_padding = padding;
if (!isBlockCipher && (m_padding == PKCS_PADDING || m_padding == ONE_AND_ZEROS_PADDING))
throw InvalidArgument("StreamTransformationFilter: PKCS_PADDING and ONE_AND_ZEROS_PADDING cannot be used with " + c.AlgorithmName());
}