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Replace FIDO2 PIN storage with its hash

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This commit is contained in:
Szczepan Zalega 2019-08-07 16:46:21 +02:00
parent 095b08e3d9
commit 7be0553377
No known key found for this signature in database
GPG Key ID: D9BAE35991DE5B22
1 changed files with 51 additions and 27 deletions
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78
fido2/ctap.c
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@ -29,7 +29,6 @@
uint8_t PIN_TOKEN[PIN_TOKEN_SIZE];
uint8_t KEY_AGREEMENT_PUB[64];
static uint8_t KEY_AGREEMENT_PRIV[32];
static uint8_t PIN_CODE_HASH[32];
static int8_t PIN_BOOT_ATTEMPTS_LEFT = PIN_BOOT_ATTEMPTS;
AuthenticatorState STATE;
@ -1362,7 +1361,13 @@ uint8_t ctap_update_pin_if_verified(uint8_t * pinEnc, int len, uint8_t * platfor
}
crypto_aes256_reset_iv(NULL);
crypto_aes256_decrypt(pinHashEnc, 16);
if (memcmp(pinHashEnc, PIN_CODE_HASH, 16) != 0)
crypto_sha256_init();
crypto_sha256_update(pinHashEnc, 16);
crypto_sha256_update(STATE.PIN_SALT, sizeof(STATE.PIN_SALT));
crypto_sha256_final(pinHashEnc);
if (memcmp(pinHashEnc, STATE.PIN_CODE_HASH, 16) != 0)
{
ctap_reset_key_agreement();
ctap_decrement_pin_attempts();
@ -1397,12 +1402,15 @@ uint8_t ctap_add_pin_if_verified(uint8_t * pinTokenEnc, uint8_t * platform_pubke
crypto_aes256_decrypt(pinHashEnc, 16);
if (memcmp(pinHashEnc, PIN_CODE_HASH, 16) != 0)
crypto_sha256_init();
crypto_sha256_update(pinHashEnc, 16);
crypto_sha256_update(STATE.PIN_SALT, sizeof(STATE.PIN_SALT));
crypto_sha256_final(pinHashEnc);
if (memcmp(pinHashEnc, STATE.PIN_CODE_HASH, 16) != 0)
{
printf2(TAG_ERR,"Pin does not match!\n");
printf2(TAG_ERR,"platform-pin-hash: "); dump_hex1(TAG_ERR, pinHashEnc, 16);
printf2(TAG_ERR,"authentic-pin-hash: "); dump_hex1(TAG_ERR, PIN_CODE_HASH, 16);
printf2(TAG_ERR,"authentic-pin-hash: "); dump_hex1(TAG_ERR, STATE.PIN_CODE_HASH, 16);
printf2(TAG_ERR,"shared-secret: "); dump_hex1(TAG_ERR, shared_secret, 32);
printf2(TAG_ERR,"platform-pubkey: "); dump_hex1(TAG_ERR, platform_pubkey, 64);
printf2(TAG_ERR,"device-pubkey: "); dump_hex1(TAG_ERR, KEY_AGREEMENT_PUB, 64);
@ -1710,6 +1718,15 @@ static void ctap_state_init()
STATE.rk_stored = 0;
ctap_reset_rk();
if (ctap_generate_rng(STATE.PIN_SALT, sizeof(STATE.PIN_SALT)) != 1) {
printf2(TAG_ERR, "Error, rng failed\n");
exit(1);
}
printf1(TAG_STOR, "Generated PIN SALT: ");
dump_hex1(TAG_STOR, STATE.PIN_SALT, sizeof STATE.PIN_SALT);
}
void ctap_init()
@ -1746,10 +1763,6 @@ void ctap_init()
if (ctap_is_pin_set())
{
printf1(TAG_STOR,"pin code: \"%s\"\n", STATE.pin_code);
crypto_sha256_init();
crypto_sha256_update(STATE.pin_code, STATE.pin_code_length);
crypto_sha256_final(PIN_CODE_HASH);
printf1(TAG_STOR, "attempts_left: %d\n", STATE.remaining_tries);
}
else
@ -1784,34 +1797,38 @@ uint8_t ctap_is_pin_set()
return STATE.is_pin_set == 1;
}
uint8_t ctap_pin_matches(uint8_t * pin, int len)
{
return memcmp(pin, STATE.pin_code, len) == 0;
}
/**
* Set new PIN, by updating PIN hash. Save state.
* Globals: PIN_CODE_HASH STATE
* @param pin new PIN (raw)
* @param len pin array length
*/
void ctap_update_pin(uint8_t * pin, int len)
{
if (len > NEW_PIN_ENC_MIN_SIZE || len < 4)
if (len >= NEW_PIN_ENC_MIN_SIZE || len < 4)
{
printf2(TAG_ERR, "Update pin fail length\n");
exit(1);
}
memset(STATE.pin_code, 0, NEW_PIN_ENC_MIN_SIZE);
memmove(STATE.pin_code, pin, len);
STATE.pin_code_length = len;
STATE.pin_code[NEW_PIN_ENC_MIN_SIZE - 1] = 0;
crypto_sha256_init();
crypto_sha256_update(STATE.pin_code, len);
crypto_sha256_final(PIN_CODE_HASH);
crypto_sha256_update(pin, len);
uint8_t intermediateHash[32];
crypto_sha256_final(intermediateHash);
crypto_sha256_init();
crypto_sha256_update(intermediateHash, 16);
memset(intermediateHash, 0, sizeof(intermediateHash));
crypto_sha256_update(STATE.PIN_SALT, sizeof(STATE.PIN_SALT));
crypto_sha256_final(STATE.PIN_CODE_HASH);
STATE.is_pin_set = 1;
authenticator_write_state(&STATE, 1);
authenticator_write_state(&STATE, 0);
printf1(TAG_CTAP, "New pin set: %s\n", STATE.pin_code);
printf1(TAG_CTAP, "New pin set: %s [%d]\n", pin, len);
dump_hex1(TAG_ERR, STATE.PIN_CODE_HASH, sizeof(STATE.PIN_CODE_HASH));
}
uint8_t ctap_decrement_pin_attempts()
@ -1828,9 +1845,7 @@ uint8_t ctap_decrement_pin_attempts()
if (ctap_device_locked())
{
memset(PIN_TOKEN,0,sizeof(PIN_TOKEN));
memset(PIN_CODE_HASH,0,sizeof(PIN_CODE_HASH));
printf1(TAG_CP, "Device locked!\n");
lock_device_permanently();
}
}
else
@ -1986,8 +2001,17 @@ void ctap_reset()
}
ctap_reset_state();
memset(PIN_CODE_HASH,0,sizeof(PIN_CODE_HASH));
ctap_reset_key_agreement();
crypto_load_master_secret(STATE.key_space);
}
void lock_device_permanently() {
memset(PIN_TOKEN, 0, sizeof(PIN_TOKEN));
memset(STATE.PIN_CODE_HASH, 0, sizeof(STATE.PIN_CODE_HASH));
printf1(TAG_CP, "Device locked!\n");
authenticator_write_state(&STATE, 0);
authenticator_write_state(&STATE, 1);
}