1 /* $OpenBSD: e_chacha.c,v 1.9 2022/07/30 17:11:38 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 <openssl/opensslconf.h>
19
20 #ifndef OPENSSL_NO_CHACHA
21
22 #include <openssl/chacha.h>
23 #include <openssl/evp.h>
24 #include <openssl/objects.h>
25
26 #include "evp_locl.h"
27
28 static int
chacha_init(EVP_CIPHER_CTX * ctx,const unsigned char * key,const unsigned char * openssl_iv,int enc)29 chacha_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
30 const unsigned char *openssl_iv, int enc)
31 {
32 if (key != NULL)
33 ChaCha_set_key((ChaCha_ctx *)ctx->cipher_data, key,
34 EVP_CIPHER_CTX_key_length(ctx) * 8);
35 if (openssl_iv != NULL) {
36 const unsigned char *iv = openssl_iv + 8;
37 const unsigned char *counter = openssl_iv;
38
39 ChaCha_set_iv((ChaCha_ctx *)ctx->cipher_data, iv, counter);
40 }
41 return 1;
42 }
43
44 static int
chacha_cipher(EVP_CIPHER_CTX * ctx,unsigned char * out,const unsigned char * in,size_t len)45 chacha_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out, const unsigned char *in,
46 size_t len)
47 {
48 ChaCha((ChaCha_ctx *)ctx->cipher_data, out, in, len);
49 return 1;
50 }
51
52 static const EVP_CIPHER chacha20_cipher = {
53 .nid = NID_chacha20,
54 .block_size = 1,
55 .key_len = 32,
56 /*
57 * The 128 bit EVP IV is split for ChaCha into four 32 bit pieces:
58 * counter[0] counter[1] iv[0] iv[1]
59 * OpenSSL exposes these as:
60 * openssl_iv = counter[0] iv[0] iv[1] iv[2]
61 * Due to the cipher internal state's symmetry, these are functionally
62 * equivalent.
63 */
64 .iv_len = 16,
65 .flags = EVP_CIPH_STREAM_CIPHER | EVP_CIPH_ALWAYS_CALL_INIT |
66 EVP_CIPH_CUSTOM_IV,
67 .init = chacha_init,
68 .do_cipher = chacha_cipher,
69 .ctx_size = sizeof(ChaCha_ctx)
70 };
71
72 const EVP_CIPHER *
EVP_chacha20(void)73 EVP_chacha20(void)
74 {
75 return (&chacha20_cipher);
76 }
77
78 #endif
79