1 files changed, 95 insertions, 0 deletions
diff --git a/stream/crypt_arc4.c b/stream/crypt_arc4.c
new file mode 100644
index 00000000..86c9afd8
--- /dev/null
+++ b/stream/crypt_arc4.c
@@ -0,0 +1,95 @@
+/*        This code illustrates a sample implementation
+ *                 of the Arcfour algorithm
+ *         Copyright (c) April 29, 1997 Kalle Kaukonen.
+ *                    All Rights Reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that this copyright
+ * notice and disclaimer are retained.
+ *
+ * THIS SOFTWARE IS PROVIDED BY KALLE KAUKONEN AND CONTRIBUTORS ``AS
+ * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL KALLE
+ * KAUKONEN OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <fitz.h>
+
+void
+fz_arc4init(fz_arc4 *arc4, unsigned char *key, unsigned keylen)
+{
+	unsigned int t, u;
+	unsigned int keyindex;
+	unsigned int stateindex;
+	unsigned char *state;
+	unsigned int counter;
+
+	state = arc4->state;
+
+	arc4->x = 0;
+	arc4->y = 0;
+
+	for (counter = 0; counter < 256; counter++) {
+		state[counter] = counter;
+	}
+
+	keyindex = 0;
+	stateindex = 0;
+
+	for (counter = 0; counter < 256; counter++) {
+		t = state[counter];
+		stateindex = (stateindex + key[keyindex] + t) & 0xff;
+		u = state[stateindex];
+
+		state[stateindex] = t;
+		state[counter] = u;
+
+		if (++keyindex >= keylen) {
+			keyindex = 0;
+		}
+	}
+}
+
+unsigned char
+fz_arc4next(fz_arc4 *arc4)
+{
+	unsigned int x;
+	unsigned int y;
+	unsigned int sx, sy;
+	unsigned char *state;
+
+	state = arc4->state;
+
+	x = (arc4->x + 1) & 0xff;
+	sx = state[x];
+	y = (sx + arc4->y) & 0xff;
+	sy = state[y];
+
+	arc4->x = x;
+	arc4->y = y;
+
+	state[y] = sx;
+	state[x] = sy;
+
+	return state[(sx + sy) & 0xff];
+}
+
+void
+fz_arc4encrypt(fz_arc4 *arc4, unsigned char *dest, unsigned char *src, unsigned len)
+{
+	unsigned int i;
+	for (i = 0; i < len; i++) {
+		unsigned char x;
+		x = fz_arc4next(arc4);
+		dest[i] = src[i] ^ x;
+	}
+}
+