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Diffstat (limited to 'tests/hazmat/test_der.py')
| -rw-r--r-- | tests/hazmat/test_der.py | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/tests/hazmat/test_der.py b/tests/hazmat/test_der.py new file mode 100644 index 00000000..d81c0d3e --- /dev/null +++ b/tests/hazmat/test_der.py @@ -0,0 +1,217 @@ +# This file is dual licensed under the terms of the Apache License, Version +# 2.0, and the BSD License. See the LICENSE file in the root of this repository +# for complete details. + +from __future__ import absolute_import, division, print_function + +import pytest + +from cryptography.hazmat._der import ( + DERReader, INTEGER, NULL, OCTET_STRING, SEQUENCE, encode_der, + encode_der_integer +) + + +def test_der_reader_basic(): + reader = DERReader(b"123456789") + assert reader.read_byte() == ord(b"1") + assert reader.read_bytes(1).tobytes() == b"2" + assert reader.read_bytes(4).tobytes() == b"3456" + + with pytest.raises(ValueError): + reader.read_bytes(4) + + assert reader.read_bytes(3).tobytes() == b"789" + + # The input is now empty. + with pytest.raises(ValueError): + reader.read_bytes(1) + with pytest.raises(ValueError): + reader.read_byte() + + +def test_der(): + # This input is the following structure, using + # https://github.com/google/der-ascii + # + # SEQUENCE { + # SEQUENCE { + # NULL {} + # INTEGER { 42 } + # OCTET_STRING { "hello" } + # } + # } + der = b"\x30\x0e\x30\x0c\x05\x00\x02\x01\x2a\x04\x05\x68\x65\x6c\x6c\x6f" + reader = DERReader(der) + with pytest.raises(ValueError): + reader.check_empty() + + # Parse the outer element. + outer = reader.read_element(SEQUENCE) + reader.check_empty() + assert outer.data.tobytes() == der[2:] + + # Parse the outer element with read_any_element. + reader = DERReader(der) + tag, outer2 = reader.read_any_element() + reader.check_empty() + assert tag == SEQUENCE + assert outer2.data.tobytes() == der[2:] + + # Parse the outer element with read_single_element. + outer3 = DERReader(der).read_single_element(SEQUENCE) + assert outer3.data.tobytes() == der[2:] + + # read_single_element rejects trailing data. + with pytest.raises(ValueError): + DERReader(der + der).read_single_element(SEQUENCE) + + # Continue parsing the structure. + inner = outer.read_element(SEQUENCE) + outer.check_empty() + + # Parsing a missing optional element should work. + assert inner.read_optional_element(INTEGER) is None + + null = inner.read_element(NULL) + null.check_empty() + + # Parsing a present optional element should work. + integer = inner.read_optional_element(INTEGER) + assert integer.as_integer() == 42 + + octet_string = inner.read_element(OCTET_STRING) + assert octet_string.data.tobytes() == b"hello" + + # Parsing a missing optional element should work when the input is empty. + inner.check_empty() + assert inner.read_optional_element(INTEGER) is None + + # Re-encode the same structure. + der2 = encode_der( + SEQUENCE, + encode_der( + SEQUENCE, + encode_der(NULL), + encode_der(INTEGER, encode_der_integer(42)), + encode_der(OCTET_STRING, b"hello"), + ) + ) + assert der2 == der + + +@pytest.mark.parametrize( + "length,header", + [ + # Single-byte lengths. + (0, b"\x04\x00"), + (1, b"\x04\x01"), + (2, b"\x04\x02"), + (127, b"\x04\x7f"), + # Long-form lengths. + (128, b"\x04\x81\x80"), + (129, b"\x04\x81\x81"), + (255, b"\x04\x81\xff"), + (0x100, b"\x04\x82\x01\x00"), + (0x101, b"\x04\x82\x01\x01"), + (0xffff, b"\x04\x82\xff\xff"), + (0x10000, b"\x04\x83\x01\x00\x00"), + ] +) +def test_der_lengths(length, header): + body = length * b"a" + der = header + body + + reader = DERReader(der) + element = reader.read_element(OCTET_STRING) + reader.check_empty() + assert element.data.tobytes() == body + + assert encode_der(OCTET_STRING, body) == der + + +@pytest.mark.parametrize( + "bad_input", + [ + # The input ended before the tag. + b"", + # The input ended before the length. + b"\x30", + # The input ended before the second byte of the length. + b"\x30\x81", + # The input ended before the body. + b"\x30\x01", + # The length used long form when it should be short form. + b"\x30\x81\x01\x00", + # The length was not minimally-encoded. + b"\x30\x82\x00\x80" + (0x80 * b"a"), + # Indefinite-length encoding is not valid DER. + b"\x30\x80\x00\x00" + # Tag number (the bottom 5 bits) 31 indicates long form tags, which we + # do not support. + b"\x1f\x00", + b"\x9f\x00", + b"\xbf\x00", + b"\xff\x00", + ] +) +def test_der_reader_bad_input(bad_input): + reader = DERReader(bad_input) + with pytest.raises(ValueError): + reader.read_any_element() + + +def test_der_reader_wrong_tag(): + reader = DERReader(b"\x04\x00") + with pytest.raises(ValueError): + reader.read_element(SEQUENCE) + + +@pytest.mark.parametrize( + "value,der", + [ + (0, b'\x00'), + (1, b'\x01'), + (2, b'\x02'), + (3, b'\x03'), + (127, b'\x7f'), + (128, b'\x00\x80'), + (0x112233445566778899aabbccddeeff, + b'\x11\x22\x33\x44\x55\x66\x77\x88\x99\xaa\xbb\xcc\xdd\xee\xff'), + ] +) +def test_integer(value, der): + assert encode_der_integer(value) == der + assert DERReader(der).as_integer() == value + + +@pytest.mark.parametrize( + "bad_input", + [ + # Zero is encoded as b"\x00", not the empty string. + b"", + # Too many leading zeros. + b"\x00\x00", + b"\x00\x7f", + # Too many leading ones. + b"\xff\xff", + b"\xff\x80", + # Negative integers are not supported. + b"\x80", + b"\x81", + b"\x80\x00\x00", + b"\xff", + ] +) +def test_invalid_integer(bad_input): + reader = DERReader(bad_input) + with pytest.raises(ValueError): + reader.as_integer() + + +def test_invalid_integer_encode(): + with pytest.raises(ValueError): + encode_der_integer(-1) + + with pytest.raises(ValueError): + encode_der_integer("not an integer") |