checkpoint -- started doing some R4 encryption support

git-svn-id: svn+q:///qpdf/trunk@807 71b93d88-0707-0410-a8cf-f5a4172ac649

1 files changed, 110 insertions, 0 deletions

diff --git a/libqpdf/Pl_AES_PDF.cc b/libqpdf/Pl_AES_PDF.cc
new file mode 100644
index 00000000..f2e58af0
--- /dev/null
+++ b/libqpdf/Pl_AES_PDF.cc
@@ -0,0 +1,110 @@
+#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;
+}