e_chacha.c revision 1.8
1/* $OpenBSD: e_chacha.c,v 1.8 2020/01/26 07:47:26 tb 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 28static int chacha_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out, 29 const unsigned char *in, size_t len); 30static int chacha_init(EVP_CIPHER_CTX *ctx, const unsigned char *key, 31 const unsigned char *iv, int enc); 32 33static const EVP_CIPHER chacha20_cipher = { 34 .nid = NID_chacha20, 35 .block_size = 1, 36 .key_len = 32, 37 /* 38 * The 128 bit EVP IV is split for ChaCha into four 32 bit pieces: 39 * counter[0] counter[1] iv[0] iv[1] 40 * OpenSSL exposes these as: 41 * openssl_iv = counter[0] iv[0] iv[1] iv[2] 42 * Due to the cipher internal state's symmetry, these are functionally 43 * equivalent. 44 */ 45 .iv_len = 16, 46 .flags = EVP_CIPH_STREAM_CIPHER | EVP_CIPH_ALWAYS_CALL_INIT | 47 EVP_CIPH_CUSTOM_IV, 48 .init = chacha_init, 49 .do_cipher = chacha_cipher, 50 .ctx_size = sizeof(ChaCha_ctx) 51}; 52 53const EVP_CIPHER * 54EVP_chacha20(void) 55{ 56 return (&chacha20_cipher); 57} 58 59static int 60chacha_init(EVP_CIPHER_CTX *ctx, const unsigned char *key, 61 const unsigned char *openssl_iv, int enc) 62{ 63 if (key != NULL) 64 ChaCha_set_key((ChaCha_ctx *)ctx->cipher_data, key, 65 EVP_CIPHER_CTX_key_length(ctx) * 8); 66 if (openssl_iv != NULL) { 67 const unsigned char *iv = openssl_iv + 8; 68 const unsigned char *counter = openssl_iv; 69 70 ChaCha_set_iv((ChaCha_ctx *)ctx->cipher_data, iv, counter); 71 } 72 return 1; 73} 74 75static int 76chacha_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out, const unsigned char *in, 77 size_t len) 78{ 79 ChaCha((ChaCha_ctx *)ctx->cipher_data, out, in, len); 80 return 1; 81} 82 83#endif 84