Rename RC4 implementation (non-bisectable)

1 files changed, 57 insertions, 0 deletions

diff --git a/libqpdf/RC4_native.cc b/libqpdf/RC4_native.cc
new file mode 100644
index 00000000..8ab242a0
--- /dev/null
+++ b/libqpdf/RC4_native.cc
@@ -0,0 +1,57 @@
+#include <qpdf/RC4.hh>
+#include <qpdf/QIntC.hh>
+
+#include <string.h>
+
+static void swap_byte(unsigned char &a, unsigned char &b)
+{
+    unsigned char t;
+
+    t = a;
+    a = b;
+    b = t;
+}
+
+RC4::RC4(unsigned char const* key_data, int key_len)
+{
+    if (key_len == -1)
+    {
+	key_len = QIntC::to_int(
+            strlen(reinterpret_cast<char const*>(key_data)));
+    }
+
+    for (int i = 0; i < 256; ++i)
+    {
+        key.state[i] = static_cast<unsigned char>(i);
+    }
+    key.x = 0;
+    key.y = 0;
+
+    int i1 = 0;
+    int i2 = 0;
+    for (int i = 0; i < 256; ++i)
+    {
+	i2 = (key_data[i1] + key.state[i] + i2) % 256;
+	swap_byte(key.state[i], key.state[i2]);
+	i1 = (i1 + 1) % key_len;
+    }
+}
+
+void
+RC4::process(unsigned char *in_data, size_t len, unsigned char* out_data)
+{
+    if (out_data == 0)
+    {
+	// Convert in place
+	out_data = in_data;
+    }
+
+    for (size_t i = 0; i < len; ++i)
+    {
+	key.x = static_cast<unsigned char>((key.x + 1) % 256);
+	key.y = static_cast<unsigned char>((key.state[key.x] + key.y) % 256);
+	swap_byte(key.state[key.x], key.state[key.y]);
+	int xor_index = (key.state[key.x] + key.state[key.y]) % 256;
+	out_data[i] = in_data[i] ^ key.state[xor_index];
+    }
+}