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Diffstat (limited to 'python/lilliput/helpers.py')
| -rw-r--r-- | python/lilliput/helpers.py | 92 |
1 files changed, 0 insertions, 92 deletions
diff --git a/python/lilliput/helpers.py b/python/lilliput/helpers.py deleted file mode 100644 index 8677f06..0000000 --- a/python/lilliput/helpers.py +++ /dev/null @@ -1,92 +0,0 @@ -from .constants import BLOCK_BITS, BLOCK_BYTES -from . import tbc - - -def ArrayToBlockbytesMatrix(array): - vector = list(array) - - blocks_nb = len(vector)//BLOCK_BYTES - - block_starts = ( - i*BLOCK_BYTES for i in range(blocks_nb) - ) - - matrix = [ - vector[start:start+BLOCK_BYTES] for start in block_starts - ] - - padding_len = len(vector)%BLOCK_BYTES - - if padding_len > 0: - padding = vector[-padding_len:] - matrix.append(padding) - - return matrix - - -def BlockbytesMatrixToBytes(matrix): - return bytes(byte for block in matrix for byte in block) - - -def XorState(state1, state2): - return [s1^s2 for (s1, s2) in zip(state1, state2)] - - -def Padding10LSB(X): - zeroes = [0] * (BLOCK_BYTES-len(X)-1) - return zeroes + [0b10000000] + X - - -def _tweakAssociatedData(t, i, padded): - t_bytes = t//8 - tweak = [0]*(t_bytes) - - mask = 0xff - for byte in range(t_bytes-1): - tweak[byte] = (i & mask) >> (byte * 8) - mask = mask << 8 - - mask = (0xf << (8 * t_bytes-1)) - tweak[-1] = (i & mask) >> ((t_bytes-1)*8) - if not padded: - tweak[-1] |= 0x20 - else: - tweak[-1] |= 0x60 - - return tweak - - -def BuildAuth(t, A, key): - Auth = [0 for byte in range(0, BLOCK_BYTES)] - l_a = len(A)//BLOCK_BYTES - need_padding = len(A)%BLOCK_BYTES > 0 - - A = ArrayToBlockbytesMatrix(A) - - for i in range(0, l_a): - tweak = _tweakAssociatedData(t, i, padded=False) - enc = tbc.encrypt(tweak, key, A[i]) - Auth = XorState(Auth, enc) - - if not need_padding: - return Auth - - tweak = _tweakAssociatedData(t, l_a, padded=True) - ad_padded = Padding10LSB(A[l_a]) - enc = tbc.encrypt(tweak, key, ad_padded) - Auth = XorState(Auth, enc) - - return Auth - - -class TagValidationError(Exception): - def __init__(self, announced, computed): - msg = '\n'.join(( - 'Invalid tag:', - announced.hex().upper()+' (announced)', - computed.hex().upper()+' (computed)' - )) - - super().__init__(msg) - self._announced = announced - self._computed = computed |
