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https://github.com/trezor/trezor-firmware.git
synced 2024-12-29 01:28:10 +00:00
60 lines
1.4 KiB
Python
60 lines
1.4 KiB
Python
from . import consts
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PIN_LOG_HALFWORDS = int(3 * (consts.WORD_SIZE / 2))
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def expand_counter(c: int) -> int:
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c = ((c << 4) | c) & 0x0F0F
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c = ((c << 2) | c) & 0x3333
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c = ((c << 1) | c) & 0x5555
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c = ((c << 1) | c) ^ 0xAAAA
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return c
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def compress_counter(c: int) -> int:
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c = c & 0x5555
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c = ((c >> 1) | c) & 0x3333
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c = ((c >> 2) | c) & 0x0F0F
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c = ((c >> 4) | c) & 0x00FF
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return c
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class PinLogBlockwise:
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def __init__(self, norcow):
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self.norcow = norcow
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def init(self):
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self._write_log(0)
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def write_attempt(self):
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self._write_log(self.get_failures_count() + 1)
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def write_success(self):
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self._write_log(0)
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def get_failures_count(self) -> int:
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return self._get_logs()
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def _get_logs(self) -> int:
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logs = self.norcow.get(consts.PIN_LOG_KEY)
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if logs is None:
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raise ValueError("No PIN logs")
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ctr = int.from_bytes(logs[:2], "little")
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fails = compress_counter(ctr)
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for i in range(2, PIN_LOG_HALFWORDS, 2):
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if fails != compress_counter(int.from_bytes(logs[i : i + 2], "little")):
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raise ValueError("PIN logs corrupted")
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return fails
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def _write_log(self, fails: int):
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ctr = expand_counter(fails)
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data = ctr.to_bytes(2, "little")
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for _ in range(1, PIN_LOG_HALFWORDS):
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data += ctr.to_bytes(2, "little")
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self.norcow.set(consts.PIN_LOG_KEY, data)
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