[project @ akuchling-20020516233050-85ce258c1e144af3]

[project @ 2002-05-16 16:30:50 by akuchling]
Move C implementation files into src/

1 files changed, 52 insertions, 0 deletions

diff --git a/src/XOR.c b/src/XOR.c
new file mode 100644
index 0000000..57af911
--- /dev/null
+++ b/src/XOR.c
@@ -0,0 +1,52 @@
+/*
+ *  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
+ *
+ * Distribute and use freely; there are no restrictions on further 
+ * dissemination and usage except those imposed by the laws of your 
+ * country of residence.
+ *
+ */
+
+#define MODULE_NAME XOR
+#define BLOCK_SIZE 1
+#define KEY_SIZE 0
+
+typedef struct 
+{
+ unsigned char key[32];
+ int keylen, last_pos;
+} stream_state;
+
+static void
+stream_init(stream_state *self, unsigned char *key, int len)
+{
+  int i;
+  
+  if (32 <= len) len=32;
+  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"