mirror of
https://github.com/trezor/trezor-firmware.git
synced 2024-12-30 18:10:56 +00:00
259 lines
7.7 KiB
C
259 lines
7.7 KiB
C
/*
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* This file is part of the Trezor project, https://trezor.io/
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*
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* Copyright (c) SatoshiLabs
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <string.h>
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#include "blake2s.h"
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#include "ed25519-donna/ed25519.h"
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#include "common.h"
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#include "flash.h"
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#include "image.h"
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static secbool compute_pubkey(uint8_t sig_m, uint8_t sig_n,
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const uint8_t *const *pub, uint8_t sigmask,
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ed25519_public_key res) {
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if (0 == sig_m || 0 == sig_n) return secfalse;
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if (sig_m > sig_n) return secfalse;
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// discard bits higher than sig_n
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sigmask &= ((1 << sig_n) - 1);
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// remove if number of set bits in sigmask is not equal to sig_m
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if (__builtin_popcount(sigmask) != sig_m) return secfalse;
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ed25519_public_key keys[sig_m];
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int j = 0;
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for (int i = 0; i < sig_n; i++) {
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if ((1 << i) & sigmask) {
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memcpy(keys[j], pub[i], 32);
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j++;
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}
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}
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return sectrue * (0 == ed25519_cosi_combine_publickeys(res, keys, sig_m));
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}
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const image_header *read_image_header(const uint8_t *const data,
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const uint32_t magic,
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const uint32_t maxsize) {
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const image_header *hdr = (const image_header *)data;
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if (hdr->magic != magic) {
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return NULL;
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}
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if (hdr->hdrlen != IMAGE_HEADER_SIZE) {
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return NULL;
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}
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// TODO: expiry mechanism needs to be ironed out before production or those
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// devices won't accept expiring bootloaders (due to boardloader write
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// protection).
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// lowest bit is used for breaking compatibility between old TT bootloaders
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// and non TT images
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// which is evaluated in check_image_model function
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if ((hdr->expiry & 0xFFFFFFFE) != 0) return secfalse;
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if (hdr->codelen > (maxsize - hdr->hdrlen)) return secfalse;
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if ((hdr->hdrlen + hdr->codelen) < 4 * 1024) return secfalse;
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if ((hdr->hdrlen + hdr->codelen) % 512 != 0) return secfalse;
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return hdr;
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}
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secbool check_image_model(const image_header *const hdr) {
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// abusing expiry field to break compatibility of non-TT images with existing
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// bootloaders/boardloaders
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#ifdef TREZOR_MODEL_T
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if (hdr->expiry == 0 && hdr->hw_model == 0 && hdr->hw_revision == 0) {
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// images for model TT older than this check
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return sectrue;
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}
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#else
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if ((hdr->expiry & 0x01) == 0) {
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// for models other than TT, expiry == 0 is unacceptable, as the image will
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// run on bootloaders older that this check
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return secfalse;
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}
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#endif
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#ifndef TREZOR_EMULATOR
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if (hdr->hw_model != HW_MODEL) {
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return secfalse;
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}
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if (hdr->hw_revision != HW_REVISION) {
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return secfalse;
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}
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#endif
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return sectrue;
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}
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void get_image_fingerprint(const image_header *const hdr, uint8_t *const out) {
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BLAKE2S_CTX ctx;
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blake2s_Init(&ctx, BLAKE2S_DIGEST_LENGTH);
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blake2s_Update(&ctx, hdr, IMAGE_HEADER_SIZE - IMAGE_SIG_SIZE);
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for (int i = 0; i < IMAGE_SIG_SIZE; i++) {
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blake2s_Update(&ctx, (const uint8_t *)"\x00", 1);
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}
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blake2s_Final(&ctx, out, BLAKE2S_DIGEST_LENGTH);
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}
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secbool check_image_header_sig(const image_header *const hdr, uint8_t key_m,
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uint8_t key_n, const uint8_t *const *keys) {
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// check header signature
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uint8_t fingerprint[32];
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get_image_fingerprint(hdr, fingerprint);
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ed25519_public_key pub;
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if (sectrue != compute_pubkey(key_m, key_n, keys, hdr->sigmask, pub))
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return secfalse;
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return sectrue *
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(0 == ed25519_sign_open(fingerprint, BLAKE2S_DIGEST_LENGTH, pub,
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*(const ed25519_signature *)hdr->sig));
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}
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secbool __wur read_vendor_header(const uint8_t *const data,
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vendor_header *const vhdr) {
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memcpy(&vhdr->magic, data, 4);
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if (vhdr->magic != 0x565A5254) return secfalse; // TRZV
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memcpy(&vhdr->hdrlen, data + 4, 4);
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if (vhdr->hdrlen > 64 * 1024) return secfalse;
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memcpy(&vhdr->expiry, data + 8, 4);
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if (vhdr->expiry != 0) return secfalse;
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vhdr->origin = data;
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memcpy(&vhdr->version, data + 12, 2);
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memcpy(&vhdr->vsig_m, data + 14, 1);
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memcpy(&vhdr->vsig_n, data + 15, 1);
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memcpy(&vhdr->vtrust, data + 16, 2);
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if (vhdr->vsig_n > MAX_VENDOR_PUBLIC_KEYS) {
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return secfalse;
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}
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for (int i = 0; i < vhdr->vsig_n; i++) {
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vhdr->vpub[i] = data + 32 + i * 32;
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}
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for (int i = vhdr->vsig_n; i < MAX_VENDOR_PUBLIC_KEYS; i++) {
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vhdr->vpub[i] = 0;
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}
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memcpy(&vhdr->vstr_len, data + 32 + vhdr->vsig_n * 32, 1);
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vhdr->vstr = (const char *)(data + 32 + vhdr->vsig_n * 32 + 1);
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vhdr->vimg = data + 32 + vhdr->vsig_n * 32 + 1 + vhdr->vstr_len;
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// align to 4 bytes
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vhdr->vimg += (-(uintptr_t)vhdr->vimg) & 3;
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memcpy(&vhdr->sigmask, data + vhdr->hdrlen - IMAGE_SIG_SIZE, 1);
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memcpy(vhdr->sig, data + vhdr->hdrlen - IMAGE_SIG_SIZE + 1,
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IMAGE_SIG_SIZE - 1);
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return sectrue;
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}
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secbool check_vendor_header_sig(const vendor_header *const vhdr, uint8_t key_m,
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uint8_t key_n, const uint8_t *const *keys) {
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if (vhdr == NULL) {
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return secfalse;
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}
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// check header signature
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uint8_t hash[BLAKE2S_DIGEST_LENGTH];
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BLAKE2S_CTX ctx;
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blake2s_Init(&ctx, BLAKE2S_DIGEST_LENGTH);
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blake2s_Update(&ctx, vhdr->origin, vhdr->hdrlen - IMAGE_SIG_SIZE);
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for (int i = 0; i < IMAGE_SIG_SIZE; i++) {
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blake2s_Update(&ctx, (const uint8_t *)"\x00", 1);
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}
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blake2s_Final(&ctx, hash, BLAKE2S_DIGEST_LENGTH);
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ed25519_public_key pub;
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if (sectrue != compute_pubkey(key_m, key_n, keys, vhdr->sigmask, pub))
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return secfalse;
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return sectrue *
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(0 == ed25519_sign_open(hash, BLAKE2S_DIGEST_LENGTH, pub,
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*(const ed25519_signature *)vhdr->sig));
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}
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void vendor_header_hash(const vendor_header *const vhdr, uint8_t *hash) {
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BLAKE2S_CTX ctx;
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blake2s_Init(&ctx, BLAKE2S_DIGEST_LENGTH);
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blake2s_Update(&ctx, vhdr->vstr, vhdr->vstr_len);
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blake2s_Update(&ctx, "Trezor Vendor Header", 20);
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blake2s_Final(&ctx, hash, BLAKE2S_DIGEST_LENGTH);
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}
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secbool check_single_hash(const uint8_t *const hash, const uint8_t *const data,
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int len) {
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uint8_t h[BLAKE2S_DIGEST_LENGTH];
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blake2s(data, len, h, BLAKE2S_DIGEST_LENGTH);
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return sectrue * (0 == memcmp(h, hash, BLAKE2S_DIGEST_LENGTH));
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}
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//
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secbool check_image_contents(const image_header *const hdr, uint32_t firstskip,
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const flash_area_t *area) {
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if (0 == area) {
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return secfalse;
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}
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const void *data =
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flash_area_get_address(area, firstskip, IMAGE_CHUNK_SIZE - firstskip);
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if (!data) {
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return secfalse;
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}
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int remaining = hdr->codelen;
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if (sectrue !=
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check_single_hash(hdr->hashes, data,
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MIN(remaining, IMAGE_CHUNK_SIZE - firstskip))) {
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return secfalse;
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}
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remaining -= IMAGE_CHUNK_SIZE - firstskip;
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int chunk = 1;
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while (remaining > 0) {
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data = flash_area_get_address(area, chunk * IMAGE_CHUNK_SIZE,
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IMAGE_CHUNK_SIZE);
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if (!data) {
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return secfalse;
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}
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if (sectrue != check_single_hash(hdr->hashes + chunk * 32, data,
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MIN(remaining, IMAGE_CHUNK_SIZE))) {
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return secfalse;
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}
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chunk++;
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remaining -= IMAGE_CHUNK_SIZE;
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}
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return sectrue;
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}
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