/*----------------------------------------------------------------------
| AP4_OmaDcfCbcSampleEncrypter::EncryptSampleData
+---------------------------------------------------------------------*/
AP4_Result
AP4_OmaDcfCbcSampleEncrypter::EncryptSampleData(AP4_DataBuffer& data_in,
AP4_DataBuffer& data_out,
AP4_UI64 counter,
bool /*skip_encryption*/)
{
// make sure there is enough space in the output buffer
data_out.Reserve(data_in.GetDataSize()+2*AP4_CIPHER_BLOCK_SIZE+1);
// setup the buffers
AP4_Size out_size = data_in.GetDataSize()+AP4_CIPHER_BLOCK_SIZE;
unsigned char* out = data_out.UseData();
// selective encryption flag
*out++ = 0x80;
// IV on 16 bytes: [SSSSSSSSXXXXXXXX]
// where SSSSSSSS is the 64-bit salt and
// XXXXXXXX is the 64-bit base counter
AP4_CopyMemory(out, m_Salt, 8);
AP4_BytesFromUInt64BE(&out[8], counter);
// encrypt the payload
m_Cipher->SetIV(out);
m_Cipher->ProcessBuffer(data_in.GetData(),
data_in.GetDataSize(),
out+AP4_CIPHER_BLOCK_SIZE,
&out_size,
true);
AP4_CHECK(data_out.SetDataSize(out_size+AP4_CIPHER_BLOCK_SIZE+1));
return AP4_SUCCESS;
}
/*----------------------------------------------------------------------
| AP4_OmaDcfCtrSampleEncrypter::EncryptSampleData
+---------------------------------------------------------------------*/
AP4_Result
AP4_OmaDcfCtrSampleEncrypter::EncryptSampleData(AP4_DataBuffer& data_in,
AP4_DataBuffer& data_out,
AP4_UI64 counter,
bool /*skip_encryption*/)
{
// setup the buffers
const unsigned char* in = data_in.GetData();
AP4_CHECK(data_out.SetDataSize(data_in.GetDataSize()+AP4_CIPHER_BLOCK_SIZE+1));
unsigned char* out = data_out.UseData();
// selective encryption flag
*out++ = 0x80;
// IV on 16 bytes: [SSSSSSSSXXXXXXXX]
// where SSSSSSSS is the 64-bit salt and
// XXXXXXXX is the 64-bit base counter
AP4_CopyMemory(out, m_Salt, 8);
AP4_BytesFromUInt64BE(&out[8], counter);
// encrypt the payload
AP4_Size data_size = data_in.GetDataSize();
m_Cipher->SetIV(out);
m_Cipher->ProcessBuffer(in, data_size, out+AP4_CIPHER_BLOCK_SIZE);
return AP4_SUCCESS;
}
/*----------------------------------------------------------------------
| AP4_BytesFromDoubleBE
+---------------------------------------------------------------------*/
void
AP4_BytesFromDoubleBE(unsigned char* bytes, double value)
{
void* v_value = reinterpret_cast<void*>(&value);
AP4_UI64* i_value = reinterpret_cast<AP4_UI64*>(v_value);
AP4_BytesFromUInt64BE(bytes, *i_value);
}
/*----------------------------------------------------------------------
| AP4_ByteStream::WriteUI64
+---------------------------------------------------------------------*/
AP4_Result
AP4_ByteStream::WriteUI64(AP4_UI64 value)
{
unsigned char buffer[8];
// convert value to bytes
AP4_BytesFromUInt64BE(buffer, value);
// write bytes to the stream
return Write((void*)buffer, 8);
}
/*----------------------------------------------------------------------
| AP4_CtrStreamCipher::ComputeCounter
+---------------------------------------------------------------------*/
void
AP4_CtrStreamCipher::ComputeCounter(AP4_UI64 stream_offset,
AP4_UI08 counter_block[AP4_CIPHER_BLOCK_SIZE])
{
// setup counter offset bytes
AP4_UI64 counter_offset = stream_offset/AP4_CIPHER_BLOCK_SIZE;
AP4_UI08 counter_offset_bytes[8];
AP4_BytesFromUInt64BE(counter_offset_bytes, counter_offset);
// compute the new counter
unsigned int carry = 0;
for (unsigned int i=0; i<m_CounterSize; i++) {
unsigned int o = AP4_CIPHER_BLOCK_SIZE-1-i;
unsigned int x = m_IV[o];
unsigned int y = (i<8)?counter_offset_bytes[7-i]:0;
unsigned int sum = x+y+carry;
counter_block[o] = (AP4_UI08)(sum&0xFF);
carry = ((sum >= 0x100)?1:0);
}
for (unsigned int i=m_CounterSize; i<AP4_CIPHER_BLOCK_SIZE; i++) {
unsigned int o = AP4_CIPHER_BLOCK_SIZE-1-i;
counter_block[o] = m_IV[o];
}
}
