1 // SPDX-License-Identifier: GPL-2.0-or-later
5 * ARC4 Cipher Algorithm
7 * Jon Oberheide <jon@oberheide.org>
10 #include <crypto/algapi.h>
11 #include <crypto/arc4.h>
12 #include <crypto/internal/skcipher.h>
13 #include <linux/init.h>
14 #include <linux/module.h>
21 static int arc4_set_key(struct crypto_tfm
*tfm
, const u8
*in_key
,
24 struct arc4_ctx
*ctx
= crypto_tfm_ctx(tfm
);
30 for (i
= 0; i
< 256; i
++)
33 for (i
= 0; i
< 256; i
++) {
35 j
= (j
+ in_key
[k
] + a
) & 0xff;
36 ctx
->S
[i
] = ctx
->S
[j
];
45 static int arc4_set_key_skcipher(struct crypto_skcipher
*tfm
, const u8
*in_key
,
48 return arc4_set_key(&tfm
->base
, in_key
, key_len
);
51 static void arc4_crypt(struct arc4_ctx
*ctx
, u8
*out
, const u8
*in
,
54 u32
*const S
= ctx
->S
;
76 *out
++ = *in
++ ^ S
[a
];
88 static void arc4_crypt_one(struct crypto_tfm
*tfm
, u8
*out
, const u8
*in
)
90 arc4_crypt(crypto_tfm_ctx(tfm
), out
, in
, 1);
93 static int ecb_arc4_crypt(struct skcipher_request
*req
)
95 struct crypto_skcipher
*tfm
= crypto_skcipher_reqtfm(req
);
96 struct arc4_ctx
*ctx
= crypto_skcipher_ctx(tfm
);
97 struct skcipher_walk walk
;
100 err
= skcipher_walk_virt(&walk
, req
, false);
102 while (walk
.nbytes
> 0) {
103 arc4_crypt(ctx
, walk
.dst
.virt
.addr
, walk
.src
.virt
.addr
,
105 err
= skcipher_walk_done(&walk
, 0);
111 static struct crypto_alg arc4_cipher
= {
113 .cra_flags
= CRYPTO_ALG_TYPE_CIPHER
,
114 .cra_blocksize
= ARC4_BLOCK_SIZE
,
115 .cra_ctxsize
= sizeof(struct arc4_ctx
),
116 .cra_module
= THIS_MODULE
,
119 .cia_min_keysize
= ARC4_MIN_KEY_SIZE
,
120 .cia_max_keysize
= ARC4_MAX_KEY_SIZE
,
121 .cia_setkey
= arc4_set_key
,
122 .cia_encrypt
= arc4_crypt_one
,
123 .cia_decrypt
= arc4_crypt_one
,
128 static struct skcipher_alg arc4_skcipher
= {
129 .base
.cra_name
= "ecb(arc4)",
130 .base
.cra_priority
= 100,
131 .base
.cra_blocksize
= ARC4_BLOCK_SIZE
,
132 .base
.cra_ctxsize
= sizeof(struct arc4_ctx
),
133 .base
.cra_module
= THIS_MODULE
,
134 .min_keysize
= ARC4_MIN_KEY_SIZE
,
135 .max_keysize
= ARC4_MAX_KEY_SIZE
,
136 .setkey
= arc4_set_key_skcipher
,
137 .encrypt
= ecb_arc4_crypt
,
138 .decrypt
= ecb_arc4_crypt
,
141 static int __init
arc4_init(void)
145 err
= crypto_register_alg(&arc4_cipher
);
149 err
= crypto_register_skcipher(&arc4_skcipher
);
151 crypto_unregister_alg(&arc4_cipher
);
155 static void __exit
arc4_exit(void)
157 crypto_unregister_alg(&arc4_cipher
);
158 crypto_unregister_skcipher(&arc4_skcipher
);
161 subsys_initcall(arc4_init
);
162 module_exit(arc4_exit
);
164 MODULE_LICENSE("GPL");
165 MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
166 MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");
167 MODULE_ALIAS_CRYPTO("arc4");