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-rw-r--r--crypto/arc4.c103
1 files changed, 103 insertions, 0 deletions
diff --git a/crypto/arc4.c b/crypto/arc4.c
new file mode 100644
index 00000000000..9efbcaae88a
--- /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>");