114 lines
2.1 KiB
C
114 lines
2.1 KiB
C
/*
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* Crypto-quality random number functions
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*
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* Author: Harlan Stenn, 2014
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*
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* This file is Copyright (c) 2014 by Network Time Foundation.
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* BSD terms apply: see the file COPYRIGHT in the distribution root for details.
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*/
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#include "config.h"
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#include <sys/types.h>
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#ifdef HAVE_UNISTD_H
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# include <unistd.h>
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#endif
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#include <stdio.h>
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#include <l_stdlib.h>
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#include <ntp_random.h>
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#ifdef USE_OPENSSL_CRYPTO_RAND
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#include <openssl/err.h>
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#include <openssl/rand.h>
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int crypto_rand_init = 0;
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#else
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# ifndef HAVE_ARC4RANDOM_BUF
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static void
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arc4random_buf(void *buf, size_t nbytes);
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void
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evutil_secure_rng_get_bytes(void *buf, size_t nbytes);
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static void
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arc4random_buf(void *buf, size_t nbytes)
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{
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evutil_secure_rng_get_bytes(buf, nbytes);
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return;
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}
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# endif
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#endif
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/*
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* As of late 2014, here's how we plan to provide cryptographic-quality
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* random numbers:
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*
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* - If we are building with OpenSSL, use RAND_poll() and RAND_bytes().
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* - Otherwise, use arc4random().
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*
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* Use of arc4random() can be forced using configure --disable-openssl-random
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*
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* We can count on arc4random existing, thru the OS or thru libevent.
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* The quality of arc4random depends on the implementor.
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*
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* RAND_poll() doesn't show up until XXX. If it's not present, we
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* need to either provide our own or use arc4random().
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*/
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/*
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* ntp_crypto_srandom:
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*
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* Initialize the random number generator, if needed by the underlying
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* crypto random number generation mechanism.
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*/
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void
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ntp_crypto_srandom(
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void
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)
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{
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#ifdef USE_OPENSSL_CRYPTO_RAND
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if (!crypto_rand_init) {
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RAND_poll();
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crypto_rand_init = 1;
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}
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#else
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/* No initialization needed for arc4random() */
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#endif
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}
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/*
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* ntp_crypto_random_buf:
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*
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* Returns 0 on success, -1 on error.
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*/
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int
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ntp_crypto_random_buf(
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void *buf,
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size_t nbytes
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)
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{
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#ifdef USE_OPENSSL_CRYPTO_RAND
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int rc;
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rc = RAND_bytes(buf, nbytes);
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if (1 != rc) {
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unsigned long err;
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char *err_str;
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err = ERR_get_error();
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err_str = ERR_error_string(err, NULL);
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/* XXX: Log the error */
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(void)&err_str;
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return -1;
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}
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return 0;
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#else
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arc4random_buf(buf, nbytes);
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return 0;
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#endif
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}
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