[project @ akuchling-20020516233050-85ce258c1e144af3]

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

1 files changed, 72 insertions, 0 deletions

diff --git a/src/ARC4.c b/src/ARC4.c
new file mode 100644
index 0000000..b160eea
--- /dev/null
+++ b/src/ARC4.c
@@ -0,0 +1,72 @@
+
+/*
+ *  arc4.c : Implementation for the Alleged-RC4 stream cipher
+ *
+ * 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 ARC4
+#define BLOCK_SIZE 1
+#define KEY_SIZE 0
+
+typedef struct 
+{
+  unsigned char state[256];
+  unsigned char x,y;
+} stream_state;
+
+/* Encryption and decryption are symmetric */
+#define stream_decrypt stream_encrypt	
+
+static void stream_encrypt(stream_state *self, unsigned char *block, 
+			   int len)
+{
+  register int i, x=self->x, y=self->y;
+
+  for (i=0; i<len; i++) 
+    {
+      x = (x + 1) % 256;
+      y = (y + self->state[x]) % 256;
+      {
+	register int t;		/* Exchange state[x] and state[y] */
+	t = self->state[x];
+	self->state[x] = self->state[y];
+	self->state[y] = t;
+      }
+      {
+	register int xorIndex;	/* XOR the data with the stream data */
+	xorIndex=(self->state[x]+self->state[y]) % 256;
+	block[i] ^= self->state[xorIndex];
+      }
+    }
+  self->x=x;
+  self->y=y;
+}
+
+
+static void stream_init(stream_state *self, unsigned char *key, int keylen)
+{
+  register int i, index1, index2;
+
+  for(i=0; i<256; i++) self->state[i]=i;
+  self->x=0; self->y=0;
+  index1=0; index2=0;
+  for(i=0; i<256; i++) 
+    {
+      register int t;
+      index2 = ( key[index1] + self->state[i] + index2) % 256;
+      t = self->state[i];
+      self->state[i] = self->state[index2];
+      self->state[index2] = t;
+      index1 = (index1 + 1) % keylen;
+    }
+}
+     
+#include "stream_template.c"
+
+