1 files changed, 103 insertions, 0 deletions

diff --git a/crypto/arc4.c b/crypto/arc4.c
new file mode 100644
index 000000000000..9efbcaae88a1
--- /dev/null
+++ b/crypto/arc4.c
@@ -0,0 +1,103 @@
+/* 
+ * Cryptographic API
+ *
+ * ARC4 Cipher Algorithm
+ *
+ * Jon Oberheide <jon@oberheide.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/crypto.h>
+
+#define ARC4_MIN_KEY_SIZE       1
+#define ARC4_MAX_KEY_SIZE       256
+#define ARC4_BLOCK_SIZE         1
+
+struct arc4_ctx {
+        u8 S[256];
+        u8 x, y;
+};
+
+static int arc4_set_key(void *ctx_arg, const u8 *in_key, unsigned int key_len, u32 *flags)
+{
+        struct arc4_ctx *ctx = ctx_arg;
+        int i, j = 0, k = 0;
+
+        ctx->x = 1;
+        ctx->y = 0;
+
+        for(i = 0; i < 256; i++)
+                ctx->S[i] = i;
+
+        for(i = 0; i < 256; i++)
+        {
+                u8 a = ctx->S[i];
+                j = (j + in_key[k] + a) & 0xff;
+                ctx->S[i] = ctx->S[j];
+                ctx->S[j] = a;
+                if(++k >= key_len)
+                        k = 0;
+        }
+
+        return 0;
+}
+
+static void arc4_crypt(void *ctx_arg, u8 *out, const u8 *in)
+{
+        struct arc4_ctx *ctx = ctx_arg;
+
+        u8 *const S = ctx->S;
+        u8 x = ctx->x;
+        u8 y = ctx->y;
+        u8 a, b;
+
+        a = S[x];
+        y = (y + a) & 0xff;
+        b = S[y];
+        S[x] = b;
+        S[y] = a;
+        x = (x + 1) & 0xff;
+        *out++ = *in ^ S[(a + b) & 0xff];
+
+        ctx->x = x;
+        ctx->y = y;
+}
+
+static struct crypto_alg arc4_alg = {
+        .cra_name               =       "arc4",
+        .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
+        .cra_blocksize          =       ARC4_BLOCK_SIZE,
+        .cra_ctxsize            =       sizeof(struct arc4_ctx),
+        .cra_module             =       THIS_MODULE,
+        .cra_list               =       LIST_HEAD_INIT(arc4_alg.cra_list),
+        .cra_u                  =       { .cipher = {
+        .cia_min_keysize        =       ARC4_MIN_KEY_SIZE,
+        .cia_max_keysize        =       ARC4_MAX_KEY_SIZE,
+        .cia_setkey             =       arc4_set_key,
+        .cia_encrypt            =       arc4_crypt,
+        .cia_decrypt            =       arc4_crypt } }
+};
+
+static int __init arc4_init(void)
+{
+        return crypto_register_alg(&arc4_alg);
+}
+
+
+static void __exit arc4_exit(void)
+{
+        crypto_unregister_alg(&arc4_alg);
+}
+
+module_init(arc4_init);
+module_exit(arc4_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
+MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");