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_big_ctrcbc_init(br_aes_big_ctrcbc_keys * ctx,const void * key,size_t len)29 br_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 
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_big_ctrcbc_ctr(const br_aes_big_ctrcbc_keys * ctx,void * ctr,void * data,size_t len)51 br_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 */
90 void
br_aes_big_ctrcbc_mac(const br_aes_big_ctrcbc_keys * ctx,void * cbcmac,const void * data,size_t len)91 br_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 */
106 void
br_aes_big_ctrcbc_encrypt(const br_aes_big_ctrcbc_keys * ctx,void * ctr,void * cbcmac,void * data,size_t len)107 br_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 */
115 void
br_aes_big_ctrcbc_decrypt(const br_aes_big_ctrcbc_keys * ctx,void * ctr,void * cbcmac,void * data,size_t len)116 br_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 */
124 const 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