Loading...
1// SPDX-License-Identifier: GPL-2.0
2
3/*
4 * OFB: Output FeedBack mode
5 *
6 * Copyright (C) 2018 ARM Limited or its affiliates.
7 * All rights reserved.
8 */
9
10#include <crypto/algapi.h>
11#include <crypto/internal/cipher.h>
12#include <crypto/internal/skcipher.h>
13#include <linux/err.h>
14#include <linux/init.h>
15#include <linux/kernel.h>
16#include <linux/module.h>
17
18static int crypto_ofb_crypt(struct skcipher_request *req)
19{
20 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
21 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
22 const unsigned int bsize = crypto_cipher_blocksize(cipher);
23 struct skcipher_walk walk;
24 int err;
25
26 err = skcipher_walk_virt(&walk, req, false);
27
28 while (walk.nbytes >= bsize) {
29 const u8 *src = walk.src.virt.addr;
30 u8 *dst = walk.dst.virt.addr;
31 u8 * const iv = walk.iv;
32 unsigned int nbytes = walk.nbytes;
33
34 do {
35 crypto_cipher_encrypt_one(cipher, iv, iv);
36 crypto_xor_cpy(dst, src, iv, bsize);
37 dst += bsize;
38 src += bsize;
39 } while ((nbytes -= bsize) >= bsize);
40
41 err = skcipher_walk_done(&walk, nbytes);
42 }
43
44 if (walk.nbytes) {
45 crypto_cipher_encrypt_one(cipher, walk.iv, walk.iv);
46 crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, walk.iv,
47 walk.nbytes);
48 err = skcipher_walk_done(&walk, 0);
49 }
50 return err;
51}
52
53static int crypto_ofb_create(struct crypto_template *tmpl, struct rtattr **tb)
54{
55 struct skcipher_instance *inst;
56 struct crypto_alg *alg;
57 int err;
58
59 inst = skcipher_alloc_instance_simple(tmpl, tb);
60 if (IS_ERR(inst))
61 return PTR_ERR(inst);
62
63 alg = skcipher_ialg_simple(inst);
64
65 /* OFB mode is a stream cipher. */
66 inst->alg.base.cra_blocksize = 1;
67
68 /*
69 * To simplify the implementation, configure the skcipher walk to only
70 * give a partial block at the very end, never earlier.
71 */
72 inst->alg.chunksize = alg->cra_blocksize;
73
74 inst->alg.encrypt = crypto_ofb_crypt;
75 inst->alg.decrypt = crypto_ofb_crypt;
76
77 err = skcipher_register_instance(tmpl, inst);
78 if (err)
79 inst->free(inst);
80
81 return err;
82}
83
84static struct crypto_template crypto_ofb_tmpl = {
85 .name = "ofb",
86 .create = crypto_ofb_create,
87 .module = THIS_MODULE,
88};
89
90static int __init crypto_ofb_module_init(void)
91{
92 return crypto_register_template(&crypto_ofb_tmpl);
93}
94
95static void __exit crypto_ofb_module_exit(void)
96{
97 crypto_unregister_template(&crypto_ofb_tmpl);
98}
99
100subsys_initcall(crypto_ofb_module_init);
101module_exit(crypto_ofb_module_exit);
102
103MODULE_LICENSE("GPL");
104MODULE_DESCRIPTION("OFB block cipher mode of operation");
105MODULE_ALIAS_CRYPTO("ofb");
106MODULE_IMPORT_NS(CRYPTO_INTERNAL);
1// SPDX-License-Identifier: GPL-2.0
2
3/*
4 * OFB: Output FeedBack mode
5 *
6 * Copyright (C) 2018 ARM Limited or its affiliates.
7 * All rights reserved.
8 */
9
10#include <crypto/algapi.h>
11#include <crypto/internal/skcipher.h>
12#include <linux/err.h>
13#include <linux/init.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16
17static int crypto_ofb_crypt(struct skcipher_request *req)
18{
19 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
20 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
21 const unsigned int bsize = crypto_cipher_blocksize(cipher);
22 struct skcipher_walk walk;
23 int err;
24
25 err = skcipher_walk_virt(&walk, req, false);
26
27 while (walk.nbytes >= bsize) {
28 const u8 *src = walk.src.virt.addr;
29 u8 *dst = walk.dst.virt.addr;
30 u8 * const iv = walk.iv;
31 unsigned int nbytes = walk.nbytes;
32
33 do {
34 crypto_cipher_encrypt_one(cipher, iv, iv);
35 crypto_xor_cpy(dst, src, iv, bsize);
36 dst += bsize;
37 src += bsize;
38 } while ((nbytes -= bsize) >= bsize);
39
40 err = skcipher_walk_done(&walk, nbytes);
41 }
42
43 if (walk.nbytes) {
44 crypto_cipher_encrypt_one(cipher, walk.iv, walk.iv);
45 crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, walk.iv,
46 walk.nbytes);
47 err = skcipher_walk_done(&walk, 0);
48 }
49 return err;
50}
51
52static int crypto_ofb_create(struct crypto_template *tmpl, struct rtattr **tb)
53{
54 struct skcipher_instance *inst;
55 struct crypto_alg *alg;
56 int err;
57
58 inst = skcipher_alloc_instance_simple(tmpl, tb);
59 if (IS_ERR(inst))
60 return PTR_ERR(inst);
61
62 alg = skcipher_ialg_simple(inst);
63
64 /* OFB mode is a stream cipher. */
65 inst->alg.base.cra_blocksize = 1;
66
67 /*
68 * To simplify the implementation, configure the skcipher walk to only
69 * give a partial block at the very end, never earlier.
70 */
71 inst->alg.chunksize = alg->cra_blocksize;
72
73 inst->alg.encrypt = crypto_ofb_crypt;
74 inst->alg.decrypt = crypto_ofb_crypt;
75
76 err = skcipher_register_instance(tmpl, inst);
77 if (err)
78 inst->free(inst);
79
80 return err;
81}
82
83static struct crypto_template crypto_ofb_tmpl = {
84 .name = "ofb",
85 .create = crypto_ofb_create,
86 .module = THIS_MODULE,
87};
88
89static int __init crypto_ofb_module_init(void)
90{
91 return crypto_register_template(&crypto_ofb_tmpl);
92}
93
94static void __exit crypto_ofb_module_exit(void)
95{
96 crypto_unregister_template(&crypto_ofb_tmpl);
97}
98
99subsys_initcall(crypto_ofb_module_init);
100module_exit(crypto_ofb_module_exit);
101
102MODULE_LICENSE("GPL");
103MODULE_DESCRIPTION("OFB block cipher mode of operation");
104MODULE_ALIAS_CRYPTO("ofb");