replace pyasn1 with asn1crypto (#3361)

* replace pyasn1 with asn1crypto

* allow trailing bytes

* fix x509 test

* update CHANGELOG.rst

* fix assert

* make asn1crypto code more idiomatic

* find tag

* final clean-up

* leave trailing byte logic unchanged

* document dependency change

* spelling

* fix spelling

2 files changed, 8 insertions, 16 deletions

diff --git a/tests/hazmat/primitives/test_asym_utils.py b/tests/hazmat/primitives/test_asym_utils.py
index bd1fa35e..4835f091 100644
--- a/tests/hazmat/primitives/test_asym_utils.py
+++ b/tests/hazmat/primitives/test_asym_utils.py
@@ -73,8 +73,7 @@ def test_decode_dss_invalid_asn1():
         decode_dss_signature(b"0\x07\x02\x01\x01\x02\x02\x01")
 
     with pytest.raises(ValueError):
-        # This is the BER "end-of-contents octets," which older versions of
-        # pyasn1 are wrongly willing to return from top-level DER decoding.
+        # This is the BER "end-of-contents octets".
         decode_dss_signature(b"\x00\x00")
 
 
diff --git a/tests/test_x509.py b/tests/test_x509.py
index 1ecf6b6a..db26f563 100644
--- a/tests/test_x509.py
+++ b/tests/test_x509.py
@@ -11,9 +11,7 @@ import os
 import sys
 import warnings
 
-from pyasn1.codec.der import decoder
-
-from pyasn1_modules import rfc2459
+from asn1crypto.x509 import Certificate
 
 import pytest
 
@@ -1458,17 +1456,12 @@ class TestRSACertificateRequest(object):
 
         cert = builder.sign(issuer_private_key, hashes.SHA256(), backend)
 
-        parsed, _ = decoder.decode(
-            cert.public_bytes(serialization.Encoding.DER),
-            asn1Spec=rfc2459.Certificate()
-        )
-        tbs_cert = parsed.getComponentByName('tbsCertificate')
-        subject = tbs_cert.getComponentByName('subject')
-        issuer = tbs_cert.getComponentByName('issuer')
-        # \x13 is printable string. The first byte of the value of the
-        # node corresponds to the ASN.1 string type.
-        assert subject[0][0][0][1][0] == b"\x13"[0]
-        assert issuer[0][0][0][1][0] == b"\x13"[0]
+        parsed = Certificate.load(
+            cert.public_bytes(serialization.Encoding.DER))
+
+        # Check that each value was encoded as an ASN.1 PRINTABLESTRING.
+        assert parsed.subject.chosen[0][0]['value'].chosen.tag == 19
+        assert parsed.issuer.chosen[0][0]['value'].chosen.tag == 19
 
 
 class TestCertificateBuilder(object):