1 files changed, 169 insertions, 0 deletions
diff --git a/crypto/arc4.c b/crypto/arc4.c
new file mode 100644
index 000000000..f1a819255
--- /dev/null
+++ b/crypto/arc4.c
@@ -0,0 +1,169 @@
+/*
+ * 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>
+#include <crypto/algapi.h>
+
+#define ARC4_MIN_KEY_SIZE	1
+#define ARC4_MAX_KEY_SIZE	256
+#define ARC4_BLOCK_SIZE		1
+
+struct arc4_ctx {
+	u32 S[256];
+	u32 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++) {
+		u32 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 arc4_ctx *ctx, u8 *out, const u8 *in,
+		       unsigned int len)
+{
+	u32 *const S = ctx->S;
+	u32 x, y, a, b;
+	u32 ty, ta, tb;
+
+	if (len == 0)
+		return;
+
+	x = ctx->x;
+	y = ctx->y;
+
+	a = S[x];
+	y = (y + a) & 0xff;
+	b = S[y];
+
+	do {
+		S[y] = a;
+		a = (a + b) & 0xff;
+		S[x] = b;
+		x = (x + 1) & 0xff;
+		ta = S[x];
+		ty = (y + ta) & 0xff;
+		tb = S[ty];
+		*out++ = *in++ ^ S[a];
+		if (--len == 0)
+			break;
+		y = ty;
+		a = ta;
+		b = tb;
+	} while (true);
+
+	ctx->x = x;
+	ctx->y = y;
+}
+
+static void arc4_crypt_one(struct crypto_tfm *tfm, u8 *out, const u8 *in)
+{
+	arc4_crypt(crypto_tfm_ctx(tfm), out, in, 1);
+}
+
+static int ecb_arc4_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
+			  struct scatterlist *src, unsigned int nbytes)
+{
+	struct arc4_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
+	struct blkcipher_walk walk;
+	int err;
+
+	blkcipher_walk_init(&walk, dst, src, nbytes);
+
+	err = blkcipher_walk_virt(desc, &walk);
+
+	while (walk.nbytes > 0) {
+		u8 *wsrc = walk.src.virt.addr;
+		u8 *wdst = walk.dst.virt.addr;
+
+		arc4_crypt(ctx, wdst, wsrc, walk.nbytes);
+
+		err = blkcipher_walk_done(desc, &walk, 0);
+	}
+
+	return err;
+}
+
+static struct crypto_alg arc4_algs[2] = { {
+	.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_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_one,
+			.cia_decrypt		=	arc4_crypt_one,
+		},
+	},
+}, {
+	.cra_name		=	"ecb(arc4)",
+	.cra_priority		=	100,
+	.cra_flags		=	CRYPTO_ALG_TYPE_BLKCIPHER,
+	.cra_blocksize		=	ARC4_BLOCK_SIZE,
+	.cra_ctxsize		=	sizeof(struct arc4_ctx),
+	.cra_alignmask		=	0,
+	.cra_type		=	&crypto_blkcipher_type,
+	.cra_module		=	THIS_MODULE,
+	.cra_u			=	{
+		.blkcipher = {
+			.min_keysize	=	ARC4_MIN_KEY_SIZE,
+			.max_keysize	=	ARC4_MAX_KEY_SIZE,
+			.setkey		=	arc4_set_key,
+			.encrypt	=	ecb_arc4_crypt,
+			.decrypt	=	ecb_arc4_crypt,
+		},
+	},
+} };
+
+static int __init arc4_init(void)
+{
+	return crypto_register_algs(arc4_algs, ARRAY_SIZE(arc4_algs));
+}
+
+static void __exit arc4_exit(void)
+{
+	crypto_unregister_algs(arc4_algs, ARRAY_SIZE(arc4_algs));
+}
+
+module_init(arc4_init);
+module_exit(arc4_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
+MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");
+MODULE_ALIAS_CRYPTO("arc4");