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#include <qpdf/Pl_AES_PDF.hh>
#include <qpdf/QIntC.hh>
#include <qpdf/QPDFCryptoProvider.hh>
#include <qpdf/QUtil.hh>
#include <cstring>
#include <stdexcept>
#include <string>
bool Pl_AES_PDF::use_static_iv = false;
Pl_AES_PDF::Pl_AES_PDF(
char const* identifier,
Pipeline* next,
bool encrypt,
unsigned char const* key,
size_t key_bytes) :
Pipeline(identifier, next),
crypto(QPDFCryptoProvider::getImpl()),
encrypt(encrypt),
cbc_mode(true),
first(true),
offset(0),
key_bytes(key_bytes),
use_zero_iv(false),
use_specified_iv(false),
disable_padding(false)
{
this->key = std::make_unique<unsigned char[]>(key_bytes);
std::memcpy(this->key.get(), key, key_bytes);
std::memset(this->inbuf, 0, this->buf_size);
std::memset(this->outbuf, 0, this->buf_size);
std::memset(this->cbc_block, 0, this->buf_size);
}
void
Pl_AES_PDF::useZeroIV()
{
this->use_zero_iv = true;
}
void
Pl_AES_PDF::disablePadding()
{
this->disable_padding = true;
}
void
Pl_AES_PDF::setIV(unsigned char const* iv, size_t bytes)
{
if (bytes != this->buf_size) {
throw std::logic_error(
"Pl_AES_PDF: specified initialization vector"
" size in bytes must be " +
std::to_string(bytes));
}
this->use_specified_iv = true;
memcpy(this->specified_iv, iv, bytes);
}
void
Pl_AES_PDF::disableCBC()
{
this->cbc_mode = false;
}
void
Pl_AES_PDF::useStaticIV()
{
use_static_iv = true;
}
void
Pl_AES_PDF::write(unsigned char const* data, size_t len)
{
size_t bytes_left = len;
unsigned char const* p = data;
while (bytes_left > 0) {
if (this->offset == this->buf_size) {
flush(false);
}
size_t available = this->buf_size - this->offset;
size_t bytes = (bytes_left < available ? bytes_left : available);
bytes_left -= bytes;
std::memcpy(this->inbuf + 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);
}
if (!this->disable_padding) {
// 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 = QIntC::to_uchar(this->buf_size - this->offset);
memset(this->inbuf + this->offset, pad, pad);
this->offset = this->buf_size;
flush(false);
}
} else {
if (this->offset != this->buf_size) {
// This is never supposed to happen as the output is always supposed to be padded.
// However, we have encountered files for which the output is not a multiple of the
// block size. In this case, pad with zeroes and hope for the best.
if (this->offset >= this->buf_size) {
throw std::logic_error("buffer overflow in AES encryption"
" pipeline");
}
std::memset(this->inbuf + this->offset, 0, this->buf_size - this->offset);
this->offset = this->buf_size;
}
flush(!this->disable_padding);
}
this->crypto->rijndael_finalize();
getNext()->finish();
}
void
Pl_AES_PDF::initializeVector()
{
if (use_zero_iv) {
for (unsigned int i = 0; i < this->buf_size; ++i) {
this->cbc_block[i] = 0;
}
} else if (use_specified_iv) {
std::memcpy(this->cbc_block, this->specified_iv, this->buf_size);
} else if (use_static_iv) {
for (unsigned int i = 0; i < this->buf_size; ++i) {
this->cbc_block[i] = static_cast<unsigned char>(14U * (1U + i));
}
} else {
QUtil::initializeWithRandomBytes(this->cbc_block, this->buf_size);
}
}
void
Pl_AES_PDF::flush(bool strip_padding)
{
if (this->offset != this->buf_size) {
throw std::logic_error("AES pipeline: flush called when buffer was not full");
}
if (first) {
first = false;
bool return_after_init = false;
if (this->cbc_mode) {
if (encrypt) {
// Set cbc_block to the initialization vector, and if not zero, write it to the
// output stream.
initializeVector();
if (!(this->use_zero_iv || this->use_specified_iv)) {
getNext()->write(this->cbc_block, this->buf_size);
}
} else if (this->use_zero_iv || this->use_specified_iv) {
// Initialize vector with zeroes; zero vector was not written to the beginning of
// the input file.
initializeVector();
} else {
// Take the first block of input as the initialization vector. There's nothing to
// write at this time.
memcpy(this->cbc_block, this->inbuf, this->buf_size);
this->offset = 0;
return_after_init = true;
}
}
this->crypto->rijndael_init(
encrypt, this->key.get(), key_bytes, this->cbc_mode, this->cbc_block);
if (return_after_init) {
return;
}
}
this->crypto->rijndael_process(this->inbuf, this->outbuf);
unsigned int bytes = this->buf_size;
if (strip_padding) {
unsigned char last = this->outbuf[this->buf_size - 1];
if (last <= this->buf_size) {
bool strip = true;
for (unsigned int i = 1; i <= last; ++i) {
if (this->outbuf[this->buf_size - i] != last) {
strip = false;
break;
}
}
if (strip) {
bytes -= last;
}
}
}
this->offset = 0;
getNext()->write(this->outbuf, bytes);
}
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