1 files changed, 104 insertions, 0 deletions
diff --git a/crypto/arc4.c b/crypto/arc4.c
new file mode 100644
index 0000000..8be47e1
--- /dev/null
+++ b/crypto/arc4.c
@@ -0,0 +1,104 @@
+/* 
+ * 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(struct crypto_tfm *tfm, const u8 *in_key,
+			unsigned int key_len)
+{
+	struct arc4_ctx *ctx = crypto_tfm_ctx(tfm);
+	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(struct crypto_tfm *tfm, u8 *out, const u8 *in)
+{
+	struct arc4_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	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>");