v4.19.13 snapshot.
diff --git a/crypto/arc4.c b/crypto/arc4.c
new file mode 100644
index 0000000..f1a8192
--- /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");