137 lines
3.9 KiB
C
137 lines
3.9 KiB
C
/* $NetBSD: wg-keygen.c,v 1.1 2020/08/20 21:28:02 riastradh Exp $ */
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/*
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* Copyright (C) Ryota Ozaki <ozaki.ryota@gmail.com>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the project nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__RCSID("$NetBSD: wg-keygen.c,v 1.1 2020/08/20 21:28:02 riastradh Exp $");
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#include <stdio.h>
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#include <stdlib.h>
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#include <err.h>
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#include <resolv.h>
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#include <string.h>
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#define KEY_LEN 32
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#define KEY_BASE64_LEN 44
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__dead static void
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usage(void)
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{
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const char *progname = getprogname();
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fprintf(stderr, "Usage:\n");
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fprintf(stderr, "\t%s : Generate a private key\n", progname);
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fprintf(stderr, "\t%s --pub : Generate a public key from a private key via stdin\n", progname);
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fprintf(stderr, "\t%s --psk : Generate a pre-shared key\n", progname);
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exit(EXIT_FAILURE);
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}
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/* Mimic crypto/external/bsd/openssh/dist/kexc25519.c */
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#define CURVE25519_SIZE 32
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extern int crypto_scalarmult_curve25519(uint8_t [CURVE25519_SIZE],
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const uint8_t [CURVE25519_SIZE], const uint8_t [CURVE25519_SIZE]);
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static void
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gen_pubkey(uint8_t key[CURVE25519_SIZE], uint8_t pubkey[CURVE25519_SIZE])
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{
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static const uint8_t basepoint[CURVE25519_SIZE] = {9};
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crypto_scalarmult_curve25519(pubkey, key, basepoint);
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}
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static void
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normalize_key(uint8_t key[KEY_LEN])
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{
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/* Mimic the official implementation, wg */
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key[0] &= 248;
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key[31] &= 127;
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key[31] |= 64;
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}
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static char *
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base64(uint8_t key[KEY_LEN])
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{
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static char key_b64[KEY_BASE64_LEN + 1];
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int error;
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error = b64_ntop(key, KEY_LEN, key_b64, KEY_BASE64_LEN + 1);
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if (error == -1)
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errx(EXIT_FAILURE, "b64_ntop failed");
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key_b64[KEY_BASE64_LEN] = '\0'; /* just in case */
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return key_b64;
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}
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int
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main(int argc, char *argv[])
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{
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uint8_t key[KEY_LEN];
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if (!(argc == 1 || argc == 2))
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usage();
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if (argc == 1) {
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arc4random_buf(key, KEY_LEN);
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normalize_key(key);
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printf("%s\n", base64(key));
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return 0;
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}
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if (strcmp(argv[1], "--psk") == 0) {
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arc4random_buf(key, KEY_LEN);
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printf("%s\n", base64(key));
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return 0;
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}
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if (strcmp(argv[1], "--pub") == 0) {
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char key_b64[KEY_BASE64_LEN + 1];
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int ret;
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char *retc;
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uint8_t pubkey[KEY_LEN];
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retc = fgets(key_b64, KEY_BASE64_LEN + 1, stdin);
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if (retc == NULL)
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err(EXIT_FAILURE, "fgets");
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key_b64[KEY_BASE64_LEN] = '\0';
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if (strlen(key_b64) != KEY_BASE64_LEN)
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errx(EXIT_FAILURE, "Invalid length of a private key");
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ret = b64_pton(key_b64, key, KEY_LEN);
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if (ret == -1)
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errx(EXIT_FAILURE, "b64_pton failed");
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gen_pubkey(key, pubkey);
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printf("%s\n", base64(pubkey));
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return 0;
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}
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usage();
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}
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