1 /* $OpenBSD: chacha.c,v 1.6 2014/07/08 14:30:23 bcook 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
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
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
40 ChaCha(ChaCha_ctx *ctx, unsigned char *out, const unsigned char *in, size_t len)
41 {
42 	unsigned char *k;
43 	int i, l;
44 
45 	/* Consume remaining keystream, if any exists. */
46 	if (ctx->unused > 0) {
47 		k = ctx->ks + 64 - ctx->unused;
48 		l = (len > ctx->unused) ? ctx->unused : len;
49 		for (i = 0; i < l; i++)
50 			*(out++) = *(in++) ^ *(k++);
51 		ctx->unused -= l;
52 		len -= l;
53 	}
54 
55 	chacha_encrypt_bytes((chacha_ctx *)ctx, in, out, (uint32_t)len);
56 }
57 
58 void
59 CRYPTO_chacha_20(unsigned char *out, const unsigned char *in, size_t len,
60     const unsigned char key[32], const unsigned char iv[8], uint64_t counter)
61 {
62 	struct chacha_ctx ctx;
63 
64 	/*
65 	 * chacha_ivsetup expects the counter to be in u8. Rather than
66 	 * converting size_t to u8 and then back again, pass a counter of
67 	 * NULL and manually assign it afterwards.
68 	 */
69 	chacha_keysetup(&ctx, key, 256);
70 	chacha_ivsetup(&ctx, iv, NULL);
71 	if (counter != 0) {
72 		ctx.input[12] = (uint32_t)counter;
73 		ctx.input[13] = (uint32_t)(counter >> 32);
74 	}
75 
76 	chacha_encrypt_bytes(&ctx, in, out, (uint32_t)len);
77 }
78