1/*
2 * Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25#include "inner.h"
26
27/* see bearssl_block.h */
28void
29br_aes_big_ctrcbc_init(br_aes_big_ctrcbc_keys *ctx,
30	const void *key, size_t len)
31{
32	ctx->vtable = &br_aes_big_ctrcbc_vtable;
33	ctx->num_rounds = br_aes_keysched(ctx->skey, key, len);
34}
35
36static void
37xorbuf(void *dst, const void *src, size_t len)
38{
39	unsigned char *d;
40	const unsigned char *s;
41
42	d = dst;
43	s = src;
44	while (len -- > 0) {
45		*d ++ ^= *s ++;
46	}
47}
48
49/* see bearssl_block.h */
50void
51br_aes_big_ctrcbc_ctr(const br_aes_big_ctrcbc_keys *ctx,
52	void *ctr, void *data, size_t len)
53{
54	unsigned char *buf, *bctr;
55	uint32_t cc0, cc1, cc2, cc3;
56
57	buf = data;
58	bctr = ctr;
59	cc3 = br_dec32be(bctr +  0);
60	cc2 = br_dec32be(bctr +  4);
61	cc1 = br_dec32be(bctr +  8);
62	cc0 = br_dec32be(bctr + 12);
63	while (len > 0) {
64		unsigned char tmp[16];
65		uint32_t carry;
66
67		br_enc32be(tmp +  0, cc3);
68		br_enc32be(tmp +  4, cc2);
69		br_enc32be(tmp +  8, cc1);
70		br_enc32be(tmp + 12, cc0);
71		br_aes_big_encrypt(ctx->num_rounds, ctx->skey, tmp);
72		xorbuf(buf, tmp, 16);
73		buf += 16;
74		len -= 16;
75		cc0 ++;
76		carry = (~(cc0 | -cc0)) >> 31;
77		cc1 += carry;
78		carry &= (~(cc1 | -cc1)) >> 31;
79		cc2 += carry;
80		carry &= (~(cc2 | -cc2)) >> 31;
81		cc3 += carry;
82	}
83	br_enc32be(bctr +  0, cc3);
84	br_enc32be(bctr +  4, cc2);
85	br_enc32be(bctr +  8, cc1);
86	br_enc32be(bctr + 12, cc0);
87}
88
89/* see bearssl_block.h */
90void
91br_aes_big_ctrcbc_mac(const br_aes_big_ctrcbc_keys *ctx,
92	void *cbcmac, const void *data, size_t len)
93{
94	const unsigned char *buf;
95
96	buf = data;
97	while (len > 0) {
98		xorbuf(cbcmac, buf, 16);
99		br_aes_big_encrypt(ctx->num_rounds, ctx->skey, cbcmac);
100		buf += 16;
101		len -= 16;
102	}
103}
104
105/* see bearssl_block.h */
106void
107br_aes_big_ctrcbc_encrypt(const br_aes_big_ctrcbc_keys *ctx,
108	void *ctr, void *cbcmac, void *data, size_t len)
109{
110	br_aes_big_ctrcbc_ctr(ctx, ctr, data, len);
111	br_aes_big_ctrcbc_mac(ctx, cbcmac, data, len);
112}
113
114/* see bearssl_block.h */
115void
116br_aes_big_ctrcbc_decrypt(const br_aes_big_ctrcbc_keys *ctx,
117	void *ctr, void *cbcmac, void *data, size_t len)
118{
119	br_aes_big_ctrcbc_mac(ctx, cbcmac, data, len);
120	br_aes_big_ctrcbc_ctr(ctx, ctr, data, len);
121}
122
123/* see bearssl_block.h */
124const br_block_ctrcbc_class br_aes_big_ctrcbc_vtable = {
125	sizeof(br_aes_big_ctrcbc_keys),
126	16,
127	4,
128	(void (*)(const br_block_ctrcbc_class **, const void *, size_t))
129		&br_aes_big_ctrcbc_init,
130	(void (*)(const br_block_ctrcbc_class *const *,
131		void *, void *, void *, size_t))
132		&br_aes_big_ctrcbc_encrypt,
133	(void (*)(const br_block_ctrcbc_class *const *,
134		void *, void *, void *, size_t))
135		&br_aes_big_ctrcbc_decrypt,
136	(void (*)(const br_block_ctrcbc_class *const *,
137		void *, void *, size_t))
138		&br_aes_big_ctrcbc_ctr,
139	(void (*)(const br_block_ctrcbc_class *const *,
140		void *, const void *, size_t))
141		&br_aes_big_ctrcbc_mac
142};
143