xnu-344.tar.gz

[apple/xnu.git] / bsd / crypto / rc4 / rc4.c

diff --git a/bsd/crypto/rc4/rc4.c b/bsd/crypto/rc4/rc4.c
new file mode 100644 (file)
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+++ b/bsd/crypto/rc4/rc4.c
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+
+/*
+ * rc4.c
+ *
+ * Copyright (c) 1996-2000 Whistle Communications, Inc.
+ * All rights reserved.
+ * 
+ * Subject to the following obligations and disclaimer of warranty, use and
+ * redistribution of this software, in source or object code forms, with or
+ * without modifications are expressly permitted by Whistle Communications;
+ * provided, however, that:
+ * 1. Any and all reproductions of the source or object code must include the
+ *    copyright notice above and the following disclaimer of warranties; and
+ * 2. No rights are granted, in any manner or form, to use Whistle
+ *    Communications, Inc. trademarks, including the mark "WHISTLE
+ *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
+ *    such appears in the above copyright notice or in the software.
+ * 
+ * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
+ * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
+ * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
+ * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
+ * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
+ * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
+ * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
+ * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
+ * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
+ * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
+ * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ *
+ * $FreeBSD: src/sys/crypto/rc4/rc4.c,v 1.2.2.1 2000/04/18 04:48:31 archie Exp $
+ */
+
+#include <sys/types.h>
+#include <crypto/rc4/rc4.h>
+
+static __inline void
+swap_bytes(u_char *a, u_char *b)
+{
+       u_char temp;
+
+       temp = *a;
+       *a = *b;
+       *b = temp;
+}
+
+/*
+ * Initialize an RC4 state buffer using the supplied key,
+ * which can have arbitrary length.
+ */
+void
+rc4_init(struct rc4_state *const state, const u_char *key, int keylen)
+{
+       u_char j;
+       int i;
+
+       /* Initialize state with identity permutation */
+       for (i = 0; i < 256; i++)
+               state->perm[i] = (u_char)i; 
+       state->index1 = 0;
+       state->index2 = 0;
+  
+       /* Randomize the permutation using key data */
+       for (j = i = 0; i < 256; i++) {
+               j += state->perm[i] + key[i % keylen]; 
+               swap_bytes(&state->perm[i], &state->perm[j]);
+       }
+}
+
+/*
+ * Encrypt some data using the supplied RC4 state buffer.
+ * The input and output buffers may be the same buffer.
+ * Since RC4 is a stream cypher, this function is used
+ * for both encryption and decryption.
+ */
+void
+rc4_crypt(struct rc4_state *const state,
+       const u_char *inbuf, u_char *outbuf, int buflen)
+{
+       int i;
+       u_char j;
+
+       for (i = 0; i < buflen; i++) {
+
+               /* Update modification indicies */
+               state->index1++;
+               state->index2 += state->perm[state->index1];
+
+               /* Modify permutation */
+               swap_bytes(&state->perm[state->index1],
+                   &state->perm[state->index2]);
+
+               /* Encrypt/decrypt next byte */
+               j = state->perm[state->index1] + state->perm[state->index2];
+               outbuf[i] = inbuf[i] ^ state->perm[j];
+       }
+}
+