1 files changed, 4 insertions, 27 deletions
diff --git a/src/cryptography/hazmat/primitives/asymmetric/utils.py b/src/cryptography/hazmat/primitives/asymmetric/utils.py
index 44bf59d1..4c2337bf 100644
--- a/src/cryptography/hazmat/primitives/asymmetric/utils.py
+++ b/src/cryptography/hazmat/primitives/asymmetric/utils.py
@@ -6,9 +6,7 @@ from __future__ import absolute_import, division, print_function
 
 import warnings
 
-from pyasn1.codec.der import decoder, encoder
-from pyasn1.error import PyAsn1Error
-from pyasn1.type import namedtype, univ
+from asn1crypto.algos import DSASignature
 
 import six
 
@@ -16,13 +14,6 @@ from cryptography import utils
 from cryptography.hazmat.primitives import hashes
 
 
-class _DSSSigValue(univ.Sequence):
-    componentType = namedtype.NamedTypes(
-        namedtype.NamedType('r', univ.Integer()),
-        namedtype.NamedType('s', univ.Integer())
-    )
-
-
 def decode_rfc6979_signature(signature):
     warnings.warn(
         "decode_rfc6979_signature is deprecated and will "
@@ -34,19 +25,8 @@ def decode_rfc6979_signature(signature):
 
 
 def decode_dss_signature(signature):
-    try:
-        data, remaining = decoder.decode(signature, asn1Spec=_DSSSigValue())
-    except PyAsn1Error:
-        raise ValueError("Invalid signature data. Unable to decode ASN.1")
-
-    if remaining:
-        raise ValueError(
-            "The signature contains bytes after the end of the ASN.1 sequence."
-        )
-
-    r = int(data.getComponentByName('r'))
-    s = int(data.getComponentByName('s'))
-    return (r, s)
+    data = DSASignature.load(signature, strict=True).native
+    return data['r'], data['s']
 
 
 def encode_rfc6979_signature(r, s):
@@ -66,10 +46,7 @@ def encode_dss_signature(r, s):
     ):
         raise ValueError("Both r and s must be integers")
 
-    sig = _DSSSigValue()
-    sig.setComponentByName('r', r)
-    sig.setComponentByName('s', s)
-    return encoder.encode(sig)
+    return DSASignature({'r': r, 's': s}).dump()
 
 
 class Prehashed(object):