1 /* $OpenBSD: chacha.c,v 1.9 2022/08/20 18:44:58 jsing Exp $ */
2 /*
3 * Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include <stdint.h>
19
20 #include <openssl/chacha.h>
21
22 #include "chacha-merged.c"
23
24 void
ChaCha_set_key(ChaCha_ctx * ctx,const unsigned char * key,uint32_t keybits)25 ChaCha_set_key(ChaCha_ctx *ctx, const unsigned char *key, uint32_t keybits)
26 {
27 chacha_keysetup((chacha_ctx *)ctx, key, keybits);
28 ctx->unused = 0;
29 }
30
31 void
ChaCha_set_iv(ChaCha_ctx * ctx,const unsigned char * iv,const unsigned char * counter)32 ChaCha_set_iv(ChaCha_ctx *ctx, const unsigned char *iv,
33 const unsigned char *counter)
34 {
35 chacha_ivsetup((chacha_ctx *)ctx, iv, counter);
36 ctx->unused = 0;
37 }
38
39 void
ChaCha(ChaCha_ctx * ctx,unsigned char * out,const unsigned char * in,size_t len)40 ChaCha(ChaCha_ctx *ctx, unsigned char *out, const unsigned char *in, size_t len)
41 {
42 unsigned char *k;
43 uint64_t n;
44 int i, l;
45
46 /* Consume remaining keystream, if any exists. */
47 if (ctx->unused > 0) {
48 k = ctx->ks + 64 - ctx->unused;
49 l = (len > ctx->unused) ? ctx->unused : len;
50 for (i = 0; i < l; i++)
51 *(out++) = *(in++) ^ *(k++);
52 ctx->unused -= l;
53 len -= l;
54 }
55
56 while (len > 0) {
57 if ((n = len) > UINT32_MAX)
58 n = UINT32_MAX;
59
60 chacha_encrypt_bytes((chacha_ctx *)ctx, in, out, (uint32_t)n);
61
62 in += n;
63 out += n;
64 len -= n;
65 }
66 }
67
68 void
CRYPTO_chacha_20(unsigned char * out,const unsigned char * in,size_t len,const unsigned char key[32],const unsigned char iv[8],uint64_t counter)69 CRYPTO_chacha_20(unsigned char *out, const unsigned char *in, size_t len,
70 const unsigned char key[32], const unsigned char iv[8], uint64_t counter)
71 {
72 struct chacha_ctx ctx;
73 uint64_t n;
74
75 /*
76 * chacha_ivsetup expects the counter to be in u8. Rather than
77 * converting size_t to u8 and then back again, pass a counter of
78 * NULL and manually assign it afterwards.
79 */
80 chacha_keysetup(&ctx, key, 256);
81 chacha_ivsetup(&ctx, iv, NULL);
82 if (counter != 0) {
83 ctx.input[12] = (uint32_t)counter;
84 ctx.input[13] = (uint32_t)(counter >> 32);
85 }
86
87 while (len > 0) {
88 if ((n = len) > UINT32_MAX)
89 n = UINT32_MAX;
90
91 chacha_encrypt_bytes(&ctx, in, out, (uint32_t)n);
92
93 in += n;
94 out += n;
95 len -= n;
96 }
97 }
98
99 void
CRYPTO_xchacha_20(unsigned char * out,const unsigned char * in,size_t len,const unsigned char key[32],const unsigned char iv[24])100 CRYPTO_xchacha_20(unsigned char *out, const unsigned char *in, size_t len,
101 const unsigned char key[32], const unsigned char iv[24])
102 {
103 uint8_t subkey[32];
104
105 CRYPTO_hchacha_20(subkey, key, iv);
106 CRYPTO_chacha_20(out, in, len, subkey, iv + 16, 0);
107 }
108