NameTypeAndValue of type "unique_indentifier" cannot be prepared

[vxgmichel]

Loosely related to issue #228 and PR #241.

Note that the NameTypeAndValue class can hold a unique_identifier which is an OctetBitString:

asn1crypto/asn1crypto/x509.py

Line 652 in af8a325

class NameTypeAndValue(Sequence):

asn1crypto/asn1crypto/x509.py

Line 677 in af8a325

'unique_identifier': OctetBitString,

However, the prepped_value property relies on the value being a unicode string:

asn1crypto/asn1crypto/x509.py

Lines 700 to 712 in af8a325

	@property
	def prepped_value(self):
	"""
	Returns the value after being processed by the internationalized string
	preparation as specified by RFC 5280
	:return:
	A unicode string
	"""
	if self._prepped is None:
	self._prepped = self._ldap_string_prep(self['value'].native)
	return self._prepped

For this reason, attempting to hash a Name with a RDNSequence that includes a unique_identifier fails with the following error:

../../miniconda/envs/parsec/lib/python3.9/site-packages/asn1crypto/x509.py:1055: in hashable
    return self.chosen.hashable
../../miniconda/envs/parsec/lib/python3.9/site-packages/asn1crypto/x509.py:949: in hashable
    return '\x1E'.join(rdn.hashable for rdn in self)
../../miniconda/envs/parsec/lib/python3.9/site-packages/asn1crypto/x509.py:949: in <genexpr>
    return '\x1E'.join(rdn.hashable for rdn in self)
../../miniconda/envs/parsec/lib/python3.9/site-packages/asn1crypto/x509.py:856: in hashable
    values = self._get_values(self)
../../miniconda/envs/parsec/lib/python3.9/site-packages/asn1crypto/x509.py:925: in _get_values
    for ntv in rdn:
../../miniconda/envs/parsec/lib/python3.9/site-packages/asn1crypto/x509.py:931: in <listcomp>
    [output.update([(ntv['type'].native, ntv.prepped_value)]) for ntv in rdn]
../../miniconda/envs/parsec/lib/python3.9/site-packages/asn1crypto/x509.py:711: in prepped_value
    self._prepped = self._ldap_string_prep(self['value'].native)
../../miniconda/envs/parsec/lib/python3.9/site-packages/asn1crypto/x509.py:749: in _ldap_string_prep
    string = re.sub('[\u00ad\u1806\u034f\u180b-\u180d\ufe0f-\uff00\ufffc]+', '', string)
pattern = '[\xad᠆͏᠋-᠍️-\uff00]+', repl = '', string = b'test_ca', count = 0, flags = 0
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
    def sub(pattern, repl, string, count=0, flags=0):
        """Return the string obtained by replacing the leftmost
        non-overlapping occurrences of the pattern in string by the
        replacement repl.  repl can be either a string or a callable;
        if a string, backslash escapes in it are processed.  If it is
        a callable, it's passed the Match object and must return
        a replacement string to be used."""
>       return _compile(pattern, flags).sub(repl, string, count)
E       TypeError: cannot use a string pattern on a bytes-like object
../../miniconda/envs/parsec/lib/python3.9/re.py:210: TypeError