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 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 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 * 73 EVP_chacha20(void) 74 { 75 return (&chacha20_cipher); 76 } 77 78 #endif 79