246 lines
7.1 KiB
C
246 lines
7.1 KiB
C
/*-
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* Copyright (c) 2000-2015 Mark R V Murray
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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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* in this position and unchanged.
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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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#include <sys/cdefs.h>
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#ifdef _KERNEL
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#include <sys/param.h>
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#include <sys/malloc.h>
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#include <sys/random.h>
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#include <sys/sysctl.h>
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#include <sys/systm.h>
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#else /* !_KERNEL */
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#include <sys/param.h>
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#include <sys/types.h>
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#include <assert.h>
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#include <inttypes.h>
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#include <signal.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <threads.h>
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#define KASSERT(x, y) assert(x)
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#define CTASSERT(x) _Static_assert(x, "CTASSERT " #x)
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#endif /* _KERNEL */
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#define CHACHA_EMBED
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#define KEYSTREAM_ONLY
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#define CHACHA_NONCE0_CTR128
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#include <crypto/chacha20/chacha.c>
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#include <crypto/rijndael/rijndael-api-fst.h>
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#include <crypto/sha2/sha256.h>
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#include <dev/random/hash.h>
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#ifdef _KERNEL
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#include <dev/random/randomdev.h>
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#endif
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/* This code presumes that RANDOM_KEYSIZE is twice as large as RANDOM_BLOCKSIZE */
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CTASSERT(RANDOM_KEYSIZE == 2*RANDOM_BLOCKSIZE);
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/* Validate that full Chacha IV is as large as the 128-bit counter */
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_Static_assert(CHACHA_STATELEN == RANDOM_BLOCKSIZE, "");
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/*
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* Knob to control use of Chacha20-based PRF for Fortuna keystream primitive.
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*
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* Benefits include somewhat faster keystream generation compared with
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* unaccelerated AES-ICM; reseeding is much cheaper than computing AES key
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* schedules.
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*/
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bool random_chachamode __read_frequently = true;
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#ifdef _KERNEL
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SYSCTL_BOOL(_kern_random, OID_AUTO, use_chacha20_cipher, CTLFLAG_RDTUN,
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&random_chachamode, 0,
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"If non-zero, use the ChaCha20 cipher for randomdev PRF (default). "
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"If zero, use AES-ICM cipher for randomdev PRF (12.x default).");
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#endif
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/* Initialise the hash */
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void
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randomdev_hash_init(struct randomdev_hash *context)
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{
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SHA256_Init(&context->sha);
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}
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/* Iterate the hash */
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void
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randomdev_hash_iterate(struct randomdev_hash *context, const void *data, size_t size)
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{
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SHA256_Update(&context->sha, data, size);
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}
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/* Conclude by returning the hash in the supplied <*buf> which must be
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* RANDOM_KEYSIZE bytes long.
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*/
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void
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randomdev_hash_finish(struct randomdev_hash *context, void *buf)
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{
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SHA256_Final(buf, &context->sha);
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}
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/* Initialise the encryption routine by setting up the key schedule
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* from the supplied <*data> which must be RANDOM_KEYSIZE bytes of binary
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* data.
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*/
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void
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randomdev_encrypt_init(union randomdev_key *context, const void *data)
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{
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if (random_chachamode) {
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chacha_keysetup(&context->chacha, data, RANDOM_KEYSIZE * 8);
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} else {
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rijndael_cipherInit(&context->cipher, MODE_ECB, NULL);
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rijndael_makeKey(&context->key, DIR_ENCRYPT, RANDOM_KEYSIZE*8, data);
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}
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}
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/*
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* Create a pseudorandom output stream of 'bytecount' bytes using a CTR-mode
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* cipher or similar. The 128-bit counter is supplied in the in-out parmeter
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* 'ctr.' The output stream goes to 'd_out.'
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*
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* If AES is used, 'bytecount' is guaranteed to be a multiple of
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* RANDOM_BLOCKSIZE.
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*/
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void
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randomdev_keystream(union randomdev_key *context, uint128_t *ctr,
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void *d_out, size_t bytecount)
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{
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size_t i, blockcount, read_chunk;
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if (random_chachamode) {
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uint128_t lectr;
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/*
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* Chacha always encodes and increments the counter little
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* endian. So on BE machines, we must provide a swapped
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* counter to chacha, and swap the output too.
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*/
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le128enc(&lectr, *ctr);
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chacha_ivsetup(&context->chacha, NULL, (const void *)&lectr);
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while (bytecount > 0) {
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/*
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* We are limited by the chacha_encrypt_bytes API to
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* u32 bytes per chunk.
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*/
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read_chunk = MIN(bytecount,
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rounddown((size_t)UINT32_MAX, CHACHA_BLOCKLEN));
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chacha_encrypt_bytes(&context->chacha, NULL, d_out,
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read_chunk);
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d_out = (char *)d_out + read_chunk;
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bytecount -= read_chunk;
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}
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/*
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* Decode Chacha-updated LE counter to native endian and store
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* it back in the caller's in-out parameter.
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*/
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chacha_ctrsave(&context->chacha, (void *)&lectr);
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*ctr = le128dec(&lectr);
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explicit_bzero(&lectr, sizeof(lectr));
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} else {
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KASSERT(bytecount % RANDOM_BLOCKSIZE == 0,
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("%s: AES mode invalid bytecount, not a multiple of native "
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"block size", __func__));
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blockcount = bytecount / RANDOM_BLOCKSIZE;
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for (i = 0; i < blockcount; i++) {
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/*-
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* FS&K - r = r|E(K,C)
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* - C = C + 1
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*/
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rijndael_blockEncrypt(&context->cipher, &context->key,
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(void *)ctr, RANDOM_BLOCKSIZE * 8, d_out);
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d_out = (char *)d_out + RANDOM_BLOCKSIZE;
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uint128_increment(ctr);
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}
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}
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}
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/*
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* Fetch a pointer to the relevant key material and its size.
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*
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* This API is expected to only be used only for reseeding, where the
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* endianness does not matter; the goal is to simply incorporate the key
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* material into the hash iterator that will produce key'.
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*
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* Do not expect the buffer pointed to by this API to match the exact
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* endianness, etc, as the key material that was supplied to
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* randomdev_encrypt_init().
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*/
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void
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randomdev_getkey(union randomdev_key *context, const void **keyp, size_t *szp)
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{
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if (!random_chachamode) {
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*keyp = &context->key.keyMaterial;
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*szp = context->key.keyLen / 8;
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return;
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}
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/* Chacha20 mode */
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*keyp = (const void *)&context->chacha.input[4];
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/* Sanity check keysize */
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if (context->chacha.input[0] == U8TO32_LITTLE(sigma) &&
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context->chacha.input[1] == U8TO32_LITTLE(&sigma[4]) &&
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context->chacha.input[2] == U8TO32_LITTLE(&sigma[8]) &&
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context->chacha.input[3] == U8TO32_LITTLE(&sigma[12])) {
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*szp = 32;
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return;
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}
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#if 0
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/*
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* Included for the sake of completeness; as-implemented, Fortuna
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* doesn't need or use 128-bit Chacha20.
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*/
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if (context->chacha->input[0] == U8TO32_LITTLE(tau) &&
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context->chacha->input[1] == U8TO32_LITTLE(&tau[4]) &&
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context->chacha->input[2] == U8TO32_LITTLE(&tau[8]) &&
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context->chacha->input[3] == U8TO32_LITTLE(&tau[12])) {
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*szp = 16;
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return;
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}
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#endif
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#ifdef _KERNEL
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panic("%s: Invalid chacha20 keysize: %16D\n", __func__,
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(void *)context->chacha.input, " ");
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#else
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raise(SIGKILL);
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#endif
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}
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