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 */
28 void
br_aes_small_ctrcbc_init(br_aes_small_ctrcbc_keys * ctx,const void * key,size_t len)29 br_aes_small_ctrcbc_init(br_aes_small_ctrcbc_keys *ctx,
30 const void *key, size_t len)
31 {
32 ctx->vtable = &br_aes_small_ctrcbc_vtable;
33 ctx->num_rounds = br_aes_keysched(ctx->skey, key, len);
34 }
35
36 static void
xorbuf(void * dst,const void * src,size_t len)37 xorbuf(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 */
50 void
br_aes_small_ctrcbc_ctr(const br_aes_small_ctrcbc_keys * ctx,void * ctr,void * data,size_t len)51 br_aes_small_ctrcbc_ctr(const br_aes_small_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_small_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 */
90 void
br_aes_small_ctrcbc_mac(const br_aes_small_ctrcbc_keys * ctx,void * cbcmac,const void * data,size_t len)91 br_aes_small_ctrcbc_mac(const br_aes_small_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_small_encrypt(ctx->num_rounds, ctx->skey, cbcmac);
100 buf += 16;
101 len -= 16;
102 }
103 }
104
105 /* see bearssl_block.h */
106 void
br_aes_small_ctrcbc_encrypt(const br_aes_small_ctrcbc_keys * ctx,void * ctr,void * cbcmac,void * data,size_t len)107 br_aes_small_ctrcbc_encrypt(const br_aes_small_ctrcbc_keys *ctx,
108 void *ctr, void *cbcmac, void *data, size_t len)
109 {
110 br_aes_small_ctrcbc_ctr(ctx, ctr, data, len);
111 br_aes_small_ctrcbc_mac(ctx, cbcmac, data, len);
112 }
113
114 /* see bearssl_block.h */
115 void
br_aes_small_ctrcbc_decrypt(const br_aes_small_ctrcbc_keys * ctx,void * ctr,void * cbcmac,void * data,size_t len)116 br_aes_small_ctrcbc_decrypt(const br_aes_small_ctrcbc_keys *ctx,
117 void *ctr, void *cbcmac, void *data, size_t len)
118 {
119 br_aes_small_ctrcbc_mac(ctx, cbcmac, data, len);
120 br_aes_small_ctrcbc_ctr(ctx, ctr, data, len);
121 }
122
123 /* see bearssl_block.h */
124 const br_block_ctrcbc_class br_aes_small_ctrcbc_vtable = {
125 sizeof(br_aes_small_ctrcbc_keys),
126 16,
127 4,
128 (void (*)(const br_block_ctrcbc_class **, const void *, size_t))
129 &br_aes_small_ctrcbc_init,
130 (void (*)(const br_block_ctrcbc_class *const *,
131 void *, void *, void *, size_t))
132 &br_aes_small_ctrcbc_encrypt,
133 (void (*)(const br_block_ctrcbc_class *const *,
134 void *, void *, void *, size_t))
135 &br_aes_small_ctrcbc_decrypt,
136 (void (*)(const br_block_ctrcbc_class *const *,
137 void *, void *, size_t))
138 &br_aes_small_ctrcbc_ctr,
139 (void (*)(const br_block_ctrcbc_class *const *,
140 void *, const void *, size_t))
141 &br_aes_small_ctrcbc_mac
142 };
143