Pl_AES_PDF.cc
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#include <qpdf/Pl_AES_PDF.hh>
#include <qpdf/QUtil.hh>
#include <cstring>
#include <assert.h>
#include <stdexcept>
Pl_AES_PDF::Pl_AES_PDF(char const* identifier, Pipeline* next,
bool encrypt, unsigned char* key_data) :
Pipeline(identifier, next),
encrypt(encrypt),
offset(0)
{
std::memset(this->buf, 0, this->buf_size);
// XXX init
}
Pl_AES_PDF::~Pl_AES_PDF()
{
// XXX finalize
}
void
Pl_AES_PDF::write(unsigned char* data, int len)
{
unsigned int bytes_left = len;
unsigned char* p = data;
while (bytes_left > 0)
{
if (this->offset == this->buf_size)
{
flush(false);
}
unsigned int available = this->buf_size - this->offset;
int bytes = (bytes_left < available ? bytes_left : available);
bytes_left -= bytes;
std::memcpy(this->buf + this->offset, p, bytes);
this->offset += bytes;
p += bytes;
}
}
void
Pl_AES_PDF::finish()
{
if (this->encrypt)
{
if (this->offset == this->buf_size)
{
flush(false);
}
// Pad as described in section 3.5.1 of version 1.7 of the PDF
// specification, including providing an entire block of padding
// if the input was a multiple of 16 bytes.
unsigned char pad = this->buf_size - this->offset;
memset(this->buf + this->offset, pad, pad);
this->offset = this->buf_size;
flush(false);
}
else
{
if (this->offset != this->buf_size)
{
throw std::runtime_error(
"aes encrypted stream length was not a multiple of " +
QUtil::int_to_string(this->buf_size) + " bytes (offset = " +
QUtil::int_to_string(this->offset) + ")");
}
flush(true);
}
getNext()->finish();
}
void
Pl_AES_PDF::flush(bool strip_padding)
{
assert(this->offset == this->buf_size);
if (this->encrypt)
{
// XXX encrypt this->buf
}
else
{
// XXX decrypt this->buf
}
unsigned int bytes = this->buf_size;
if (strip_padding)
{
unsigned char last = this->buf[this->buf_size - 1];
if (last <= this->buf_size)
{
bool strip = true;
for (unsigned int i = 1; i <= last; ++i)
{
if (this->buf[this->buf_size - i] != last)
{
strip = false;
break;
}
}
if (strip)
{
bytes -= last;
}
}
}
getNext()->write(this->buf, bytes);
this->offset = 0;
}