147 lines
4.1 KiB
C
147 lines
4.1 KiB
C
#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 "image.h"
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static bool compute_pubkey(uint8_t sig_m, uint8_t sig_n, const uint8_t * const *pub, uint8_t sigmask, ed25519_public_key res)
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{
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if (!sig_m || !sig_n) return false;
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if (sig_m > sig_n) return false;
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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 false;
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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 0 == ed25519_cosi_combine_publickeys(res, keys, sig_m);
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}
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bool image_parse_header(const uint8_t *data, uint32_t magic, uint32_t maxsize, image_header *hdr)
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{
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if (!hdr) {
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image_header h;
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hdr = &h;
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}
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memcpy(&hdr->magic, data, 4);
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if (hdr->magic != magic) return false;
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memcpy(&hdr->hdrlen, data + 4, 4);
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if (hdr->hdrlen != HEADER_SIZE) return false;
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memcpy(&hdr->expiry, data + 8, 4);
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if (hdr->expiry != 0) return false;
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memcpy(&hdr->codelen, data + 12, 4);
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if (hdr->hdrlen + hdr->codelen < 4 * 1024) return false;
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if (hdr->hdrlen + hdr->codelen > maxsize) return false;
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if ((hdr->hdrlen + hdr->codelen) % 512 != 0) return false;
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memcpy(&hdr->version, data + 16, 4);
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// uint8_t reserved[427];
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memcpy(&hdr->sigmask, data + 0x01BF, 1);
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memcpy(hdr->sig, data + 0x01C0, 64);
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return true;
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}
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bool image_check_signature(const uint8_t *data, const image_header *hdr, uint8_t key_m, uint8_t key_n, const uint8_t * const *keys)
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{
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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, data, HEADER_SIZE - 65);
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for (int i = 0; i < 65; i++) {
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blake2s_Update(&ctx, (const uint8_t *)"\x00", 1);
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}
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blake2s_Update(&ctx, data + HEADER_SIZE, hdr->codelen);
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blake2s_Final(&ctx, hash, BLAKE2S_DIGEST_LENGTH);
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ed25519_public_key pub;
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if (!compute_pubkey(key_m, key_n, keys, hdr->sigmask, pub)) return false;
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return 0 == ed25519_sign_open(hash, BLAKE2S_DIGEST_LENGTH, pub, *(const ed25519_signature *)hdr->sig);
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}
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bool vendor_parse_header(const uint8_t *data, vendor_header *vhdr)
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{
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if (!vhdr) {
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vendor_header h;
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vhdr = &h;
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}
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memcpy(&vhdr->magic, data, 4);
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if (vhdr->magic != 0x565A5254) return false; // TRZV
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memcpy(&vhdr->hdrlen, data + 4, 4);
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memcpy(&vhdr->expiry, data + 8, 4);
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if (vhdr->expiry != 0) return false;
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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, 1);
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if (vhdr->vsig_n > MAX_VENDOR_PUBLIC_KEYS) {
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return false;
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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 = 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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// uint8_t reserved[427];
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memcpy(&vhdr->sigmask, data + vhdr->hdrlen - 65, 1);
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memcpy(vhdr->sig, data + vhdr->hdrlen - 64, 64);
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return true;
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}
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bool vendor_check_signature(const uint8_t *data, const vendor_header *vhdr, uint8_t key_m, uint8_t key_n, const uint8_t * const *keys)
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{
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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, data, vhdr->hdrlen - 65);
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for (int i = 0; i < 65; 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 (!compute_pubkey(key_m, key_n, keys, vhdr->sigmask, pub)) return false;
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return 0 == ed25519_sign_open(hash, BLAKE2S_DIGEST_LENGTH, pub, *(const ed25519_signature *)vhdr->sig);
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}
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