1 files changed, 76 insertions, 0 deletions
diff --git a/src/XOR.c b/src/XOR.c
new file mode 100644
index 0000000..d994749
--- /dev/null
+++ b/src/XOR.c
@@ -0,0 +1,76 @@
+/*
+ *  xor.c : Source for the trivial cipher which XORs the message with the key.
+ *          The key can be up to 32 bytes long.
+ *
+ * Part of the Python Cryptography Toolkit
+ *
+ * Contributed by Barry Warsaw and others.
+ *
+ * =======================================================================
+ * The contents of this file are dedicated to the public domain.  To the
+ * extent that dedication to the public domain is not available, everyone
+ * is granted a worldwide, perpetual, royalty-free, non-exclusive license
+ * to exercise all rights associated with the contents of this file for
+ * any purpose whatsoever.  No rights are reserved.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ * =======================================================================
+ */
+
+#include "pycrypto_common.h"
+
+#define MODULE_NAME _XOR
+#define BLOCK_SIZE 1
+#define KEY_SIZE 0
+
+#define MAX_KEY_SIZE 32
+
+typedef struct 
+{
+	unsigned char key[MAX_KEY_SIZE];
+	int keylen, last_pos;
+} stream_state;
+
+static void
+stream_init(stream_state *self, unsigned char *key, int len)
+{
+	int i;
+
+        if (len > MAX_KEY_SIZE)
+        {
+		PyErr_Format(PyExc_ValueError,
+				"XOR key must be no longer than %d bytes",
+                                MAX_KEY_SIZE);
+		return;
+        }
+	self->keylen = len;
+	self->last_pos = 0;
+
+	for(i=0; i<len; i++)
+	{
+		self->key[i] = key[i];
+	}
+}
+
+/* Encryption and decryption are symmetric */
+#define stream_decrypt stream_encrypt	
+
+static void stream_encrypt(stream_state *self, unsigned char *block, 
+			   int len)
+{
+	int i, j = self->last_pos;
+	for(i=0; i<len; i++, j=(j+1) % self->keylen)
+	{
+		block[i] ^= self->key[j];
+	}
+	self->last_pos = j;
+}
+
+#include "stream_template.c"