104 lines
3.0 KiB
C
104 lines
3.0 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 "crypto.h"
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#define FLASH_BASE 0x08000000
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bool parse_header(const uint8_t *data, uint32_t *codelen, uint8_t *sigidx, uint8_t *sig)
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{
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uint32_t magic;
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memcpy(&magic, data, 4);
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if (magic != 0x4C5A5254) return false; // TRZL
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uint32_t hdrlen;
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memcpy(&hdrlen, data + 4, 4);
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if (hdrlen != 256) return false;
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uint32_t expiry;
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memcpy(&expiry, data + 8, 4);
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if (expiry != 0) return false;
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uint32_t clen;
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memcpy(&clen, data + 12, 4);
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// stage 2 (+header) must fit into sectors 4...11 - see docs/memory.md for more info
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if (clen + hdrlen < 4 * 1024) return false;
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if (clen + hdrlen > 64 * 1024 + 7 * 128 * 1024) return false;
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if ((clen + hdrlen) % 512 != 0) return false;
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if (codelen) {
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*codelen = clen;
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}
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uint32_t version;
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memcpy(&version, data + 16, 4);
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// uint8_t reserved[171];
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if (sigidx) {
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memcpy(sigidx, data + 0x00BF, 1);
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}
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if (sig) {
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memcpy(sig, data + 0x00C0, 64);
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}
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return true;
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}
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#define KEYMASK(A, B, C) ((1 << (A - 1)) | (1 << (B - 1)) | (1 << (C - 1)))
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const uint8_t *get_pubkey(uint8_t index)
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{
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switch (index) {
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case KEYMASK(1, 2, 3):
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return (const uint8_t *)"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
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case KEYMASK(1, 2, 4):
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return (const uint8_t *)"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
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case KEYMASK(1, 2, 5):
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return (const uint8_t *)"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
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case KEYMASK(1, 3, 4):
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return (const uint8_t *)"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
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case KEYMASK(1, 3, 5):
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return (const uint8_t *)"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
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case KEYMASK(1, 4, 5):
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return (const uint8_t *)"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
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case KEYMASK(2, 3, 4):
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return (const uint8_t *)"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
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case KEYMASK(2, 3, 5):
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return (const uint8_t *)"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
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case KEYMASK(2, 4, 5):
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return (const uint8_t *)"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
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case KEYMASK(3, 4, 5):
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return (const uint8_t *)"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
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default:
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return NULL;
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}
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}
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bool check_signature(const uint8_t *start)
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{
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uint32_t codelen;
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uint8_t sigidx;
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uint8_t sig[64];
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if (!parse_header(start, &codelen, &sigidx, sig)) {
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return false;
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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, start, 256 - 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, start + 256, codelen);
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blake2s_Final(&ctx, hash, BLAKE2S_DIGEST_LENGTH);
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const uint8_t *pub = get_pubkey(sigidx);
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return pub && (0 == ed25519_sign_open(hash, BLAKE2S_DIGEST_LENGTH, *(const ed25519_public_key *)pub, *(const ed25519_signature *)sig));
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}
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