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Validate mariko keyslot contents; dump class keys

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This commit is contained in:
shchmue 2021-08-21 16:02:19 -06:00
parent fe17b12ea7
commit d84ab5796a
3 changed files with 104 additions and 10 deletions
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74
source/keys/keys.c
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@ -682,15 +682,28 @@ static bool _derive_emmc_keys(key_derivation_ctx_t *keys, titlekey_buffer_t *tit
// The security engine supports partial key override for locked keyslots
// This allows for a manageable brute force on a PC
// Then we can recover the Mariko KEK, BEK, unique SBK and SSK
static void _save_mariko_partial_keys(char *text_buffer) {
// Then the Mariko AES class keys, KEK, BEK, unique SBK and SSK can be recovered
static void _save_mariko_partial_keys(u32 start, u32 count, bool append) {
if (start + count > SE_AES_KEYSLOT_COUNT) {
return;
}
u32 pos = 0;
u32 zeros[4] = {0};
u8 *data = malloc(4 * AES_128_KEY_SIZE);
for (u32 ks = 12; ks < 16; ks++) {
// First, encrypt zeros with complete key
char *text_buffer = calloc(1, 0x100 * count);
for (u32 ks = start; ks < start + count; ks++) {
// Check if key is as expected
if (ks < ARRAY_SIZE(mariko_key_vectors)) {
se_aes_crypt_block_ecb(ks, 0, &data[0], mariko_key_vectors[ks]);
if (_key_exists(data)) {
continue;
}
}
// Encrypt zeros with complete key
se_aes_crypt_block_ecb(ks, 1, &data[3 * AES_128_KEY_SIZE], zeros);
pos += s_printf(&text_buffer[pos], "%d\n", ks);
// We only need to overwrite 3 of the dwords of the key
for (u32 i = 0; i < 3; i++) {
@ -699,15 +712,49 @@ static void _save_mariko_partial_keys(char *text_buffer) {
// Encrypt zeros with more of the key zeroed out
se_aes_crypt_block_ecb(ks, 1, &data[(2 - i) * AES_128_KEY_SIZE], zeros);
}
// Skip saving key if two results are the same indicating unsuccessful overwrite or empty slot
if (memcmp(&data[0], &data[SE_KEY_128_SIZE], AES_128_KEY_SIZE) == 0) {
continue;
}
pos += s_printf(&text_buffer[pos], "%d\n", ks);
for (u32 i = 0; i < 4; i++) {
for (u32 j = 0; j < AES_128_KEY_SIZE; j++)
pos += s_printf(&text_buffer[pos], "%02x", data[i * AES_128_KEY_SIZE + j]);
pos += s_printf(&text_buffer[pos], "\n");
pos += s_printf(&text_buffer[pos], " ");
}
pos += s_printf(&text_buffer[pos], "\n");
}
free(data);
sd_save_to_file(text_buffer, strlen(text_buffer), "sd:/switch/partialaes.keys");
if (strlen(text_buffer) == 0) {
EPRINTF("Failed to dump partial keys.");
return;
}
FIL fp;
u32 res = 0;
BYTE mode = FA_WRITE;
if (append) {
mode |= FA_OPEN_APPEND;
} else {
mode |= FA_CREATE_ALWAYS;
}
res = f_open(&fp, "sd:/switch/partialaes.keys", mode);
if (res) {
EPRINTF("Unable to write partial keys to SD.");
return;
}
f_write(&fp, text_buffer, strlen(text_buffer), NULL);
f_close(&fp);
gfx_printf("%kWrote partials to sd:/switch/partialaes.keys\n", colors[(color_idx++) % 6]);
free(text_buffer);
}
static void _save_keys_to_sd(key_derivation_ctx_t *keys, titlekey_buffer_t *titlekey_buffer, const pkg1_id_t *pkg1_id, u32 start_whole_operation_time, u32 derivable_key_count) {
@ -797,8 +844,7 @@ static void _save_keys_to_sd(key_derivation_ctx_t *keys, titlekey_buffer_t *titl
EPRINTF("Unable to save keys to SD.");
if (h_cfg.t210b01) {
memset(text_buffer, 0, text_buffer_size);
_save_mariko_partial_keys(text_buffer);
_save_mariko_partial_keys(12, 4, true);
}
if (_titlekey_count == 0) {
@ -836,8 +882,16 @@ static bool _check_keyslot_access() {
}
static void _derive_keys() {
if (!f_stat("sd:/switch/partialaes.keys", NULL)) {
f_unlink("sd:/switch/partialaes.keys");
}
if (h_cfg.t210b01) {
_save_mariko_partial_keys(0, 12, false);
}
if (!_check_keyslot_access()) {
EPRINTF("Unable to set crypto keyslots!\nTry launching payload differently\n or flash Spacecraft-NX if using a modchip!");
EPRINTF("Unable to set crypto keyslots!\nTry launching payload differently\n or flash Spacecraft-NX if using a modchip.");
return;
}