// SPDX-License-Identifier: GPL-2.0-or-later
  /*
   * Cryptographic API
   *
   * ARC4 Cipher Algorithm
   *
   * Jon Oberheide <jon@oberheide.org>
   */
  
  #include <crypto/algapi.h>
  #include <crypto/arc4.h>
  #include <crypto/internal/skcipher.h>
  #include <linux/init.h>
  #include <linux/module.h>
  
  static int crypto_arc4_setkey(struct crypto_skcipher *tfm, const u8 *in_key,
  			      unsigned int key_len)
  {
  	struct arc4_ctx *ctx = crypto_skcipher_ctx(tfm);
  
  	return arc4_setkey(ctx, in_key, key_len);
  }
  
  static int crypto_arc4_crypt(struct skcipher_request *req)
  {
  	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  	struct arc4_ctx *ctx = crypto_skcipher_ctx(tfm);
  	struct skcipher_walk walk;
  	int err;
  
  	err = skcipher_walk_virt(&walk, req, false);
  
  	while (walk.nbytes > 0) {
  		arc4_crypt(ctx, walk.dst.virt.addr, walk.src.virt.addr,
  			   walk.nbytes);
  		err = skcipher_walk_done(&walk, 0);
  	}
  
  	return err;
  }
  
  static struct skcipher_alg arc4_alg = {
  	/*
  	 * For legacy reasons, this is named "ecb(arc4)", not "arc4".
  	 * Nevertheless it's actually a stream cipher, not a block cipher.
  	 */
  	.base.cra_name		=	"ecb(arc4)",
  	.base.cra_driver_name	=	"ecb(arc4)-generic",
  	.base.cra_priority	=	100,
  	.base.cra_blocksize	=	ARC4_BLOCK_SIZE,
  	.base.cra_ctxsize	=	sizeof(struct arc4_ctx),
  	.base.cra_module	=	THIS_MODULE,
  	.min_keysize		=	ARC4_MIN_KEY_SIZE,
  	.max_keysize		=	ARC4_MAX_KEY_SIZE,
  	.setkey			=	crypto_arc4_setkey,
  	.encrypt		=	crypto_arc4_crypt,
  	.decrypt		=	crypto_arc4_crypt,
  };
  
  static int __init arc4_init(void)
  {
  	return crypto_register_skcipher(&arc4_alg);
  }
  
  static void __exit arc4_exit(void)
  {
  	crypto_unregister_skcipher(&arc4_alg);
  }
  
  subsys_initcall(arc4_init);
  module_exit(arc4_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
  MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");
  MODULE_ALIAS_CRYPTO("ecb(arc4)");