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# compatibility with Python 2.6, for that we need unittest2 package,
# which is not available on 3.3 or 3.4
try:
import unittest2 as unittest
except ImportError:
import unittest
from .der import remove_integer, UnexpectedDER, read_length
from six import b
class TestRemoveInteger(unittest.TestCase):
# DER requires the integers to be 0-padded only if they would be
# interpreted as negative, check if those errors are detected
def test_non_minimal_encoding(self):
with self.assertRaises(UnexpectedDER):
remove_integer(b('\x02\x02\x00\x01'))
def test_negative_with_high_bit_set(self):
with self.assertRaises(UnexpectedDER):
remove_integer(b('\x02\x01\x80'))
def test_two_zero_bytes_with_high_bit_set(self):
with self.assertRaises(UnexpectedDER):
remove_integer(b('\x02\x03\x00\x00\xff'))
def test_zero_length_integer(self):
with self.assertRaises(UnexpectedDER):
remove_integer(b('\x02\x00'))
def test_empty_string(self):
with self.assertRaises(UnexpectedDER):
remove_integer(b(''))
def test_encoding_of_zero(self):
val, rem = remove_integer(b('\x02\x01\x00'))
self.assertEqual(val, 0)
self.assertFalse(rem)
def test_encoding_of_127(self):
val, rem = remove_integer(b('\x02\x01\x7f'))
self.assertEqual(val, 127)
self.assertFalse(rem)
def test_encoding_of_128(self):
val, rem = remove_integer(b('\x02\x02\x00\x80'))
self.assertEqual(val, 128)
self.assertFalse(rem)
class TestReadLength(unittest.TestCase):
# DER requires the lengths between 0 and 127 to be encoded using the short
# form and lengths above that encoded with minimal number of bytes
# necessary
def test_zero_length(self):
self.assertEqual((0, 1), read_length(b('\x00')))
def test_two_byte_zero_length(self):
with self.assertRaises(UnexpectedDER):
read_length(b('\x81\x00'))
def test_two_byte_small_length(self):
with self.assertRaises(UnexpectedDER):
read_length(b('\x81\x7f'))
def test_long_form_with_zero_length(self):
with self.assertRaises(UnexpectedDER):
read_length(b('\x80'))
def test_smallest_two_byte_length(self):
self.assertEqual((128, 2), read_length(b('\x81\x80')))
def test_zero_padded_length(self):
with self.assertRaises(UnexpectedDER):
read_length(b('\x82\x00\x80'))
def test_two_three_byte_length(self):
self.assertEqual((256, 3), read_length(b'\x82\x01\x00'))
def test_empty_string(self):
with self.assertRaises(UnexpectedDER):
read_length(b(''))
def test_length_overflow(self):
with self.assertRaises(UnexpectedDER):
read_length(b('\x83\x01\x00'))
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