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Merge pull request #16 from jhoenicke/master

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PIN handling - constant time.
This commit is contained in:
Pavol Rusnak 2015-02-26 11:38:53 +01:00
commit 402886e00d
3 changed files with 22 additions and 11 deletions
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6
firmware/protect.c
View File

@ -156,16 +156,16 @@ bool protectPin(bool use_cached)
delay(10000000);
}
}
storage_increasePinFails();
bool increase_failed = (fails >= storage_getPinFails());
const char *pin;
pin = requestPin(PinMatrixRequestType_PinMatrixRequestType_Current, "Please enter current PIN:");
if (!pin) {
fsm_sendFailure(FailureType_Failure_PinCancelled, "PIN Cancelled");
return false;
}
storage_increasePinFails();
bool increase_failed = (fails >= storage_getPinFails());
if (storage_isPinCorrect(pin) && !increase_failed) {
session_cachePin(pin);
session_cachePin();
storage_resetPinFails();
return true;
} else {

25
firmware/storage.c
View File

@ -48,7 +48,6 @@ static bool sessionRootNodeCached;
static HDNode sessionRootNode;
static bool sessionPinCached;
static char sessionPin[17];
static bool sessionPassphraseCached;
static char sessionPassphrase[51];
@ -122,7 +121,7 @@ void session_clear(void)
{
sessionRootNodeCached = false; memset(&sessionRootNode, 0, sizeof(sessionRootNode));
sessionPassphraseCached = false; memset(&sessionPassphrase, 0, sizeof(sessionPassphrase));
sessionPinCached = false; memset(&sessionPin, 0, sizeof(sessionPin));
sessionPinCached = false;
}
static uint8_t meta_backup[FLASH_META_LEN];
@ -306,14 +305,27 @@ const uint8_t *storage_getHomescreen(void)
return (storage.has_homescreen && storage.homescreen.size == 1024) ? storage.homescreen.bytes : 0;
}
/* Check whether pin matches storage. The pin must be a null-terminated
* string with at most 9 characters.
*/
bool storage_isPinCorrect(const char *pin)
{
return strcmp(storage.pin, pin) == 0;
/* The execution time of the following code only depends on the
* (public) input. This avoids timing attacks.
*/
char diff = 0;
uint32_t i = 0;
while (pin[i]) {
diff |= storage.pin[i] - pin[i];
i++;
}
diff |= storage.pin[i];
return diff == 0;
}
bool storage_hasPin(void)
{
return storage.has_pin && strlen(storage.pin) > 0;
return storage.has_pin && storage.pin[0] != 0;
}
void storage_setPin(const char *pin)
@ -340,15 +352,14 @@ bool session_isPassphraseCached(void)
return sessionPassphraseCached;
}
void session_cachePin(const char *pin)
void session_cachePin(void)
{
strlcpy(sessionPin, pin, sizeof(sessionPin));
sessionPinCached = true;
}
bool session_isPinCached(void)
{
return sessionPinCached && strcmp(sessionPin, storage.pin) == 0;
return sessionPinCached;
}
void storage_resetPinFails(void)

2
firmware/storage.h
View File

@ -52,7 +52,7 @@ bool session_isPassphraseCached(void);
bool storage_isPinCorrect(const char *pin);
bool storage_hasPin(void);
void storage_setPin(const char *pin);
void session_cachePin(const char *pin);
void session_cachePin(void);
bool session_isPinCached(void);
void storage_resetPinFails(void);
void storage_increasePinFails(void);