public CSAStreamEncryptor(CSAKeyStruct ks, byte[] data_in, int len)
{
_data = data_in;
_ks = ks;
_len = len;
}
// constructor
public CSABlockEncryptor(CSAKeyStruct ks, byte[] data_in, int len)
{
_data = data_in;
_ks = ks;
_len = len;
}
public CSABlockDecryptor(CSAKeyStruct ks, byte[] data_in, int len)
{
_data = data_in;
_ks = ks;
_len = len;
}
public byte[] Decrypt(byte[] cw, byte[] data, int len)
{
// bypassed bitwise operation, not sure if it works
// it seems to set alen to length from start of packet to end of last 8 byte block, leaving residue untouched
// can probably do it in a more .NET way
//uint alen = len & unchecked((uint)~0x7);
int alen = len; //TODO: implement length checking, this is only good for 184 byte packets (or multiples of 8 bytes)
CSAKeyStruct ks = new CSAKeyStruct(cw);
int i;
if (len < 8)
{
return(data);
}
// perform stream decipher
if (_enableStream)
{
// dvbcsa_stream_xor(key->cws, data, data + 8, len - 8);
}
// perform block decipher
if (_enableBlock)
{
CSABlockDecryptor enc = new CSABlockDecryptor(ks, data, len);
enc.CSABlockDecrypt(0);
for (i = 8; i < 183; i += 8) // this needs a look
{
enc.CSAXor64(i);
enc.CSABlockDecrypt(i);
}
}
return(data);
}
public byte[] Encrypt(byte[] cw, byte[] data, int len)
{
// bypassed bitwise operation, not sure if it works
// it seems to set alen to length from start of packet to end of last 8 byte block, leaving residue untouched
// can probably do it in a more .NET way
//uint alen = len & unchecked((uint)~0x7);
int alen = len; //TODO: implement length checking, this is only good for 184 byte packets (or multiples of 8 bytes)
CSAKeyStruct ks = new CSAKeyStruct(cw);
int i;
if (len < 8)
return data;
// perform block cipher
if (_enableBlock)
{
CSABlockEncryptor enc = new CSABlockEncryptor(ks, data, len);
enc.CSABlockEncrypt(alen - 8); //(cw->sch, data + alen - 8, data + alen - 8);
for (i = alen - 16; i >= 0; i -= 8)
{
enc.CSAXor64(i); //(data + i, data + i + 8);
enc.CSABlockEncrypt(i); //(cw->sch, data + i, data + i);
}
}
// perform stream cipher
if (_enableStream)
{
// dvbcsa_stream_xor(key->cws, data, data + 8, len - 8);
}
return data;
}
