diff --git a/test/soft_u2f_v2.py b/test/soft_u2f_v2.py
index d011b1f..9a24bb9 100644
--- a/test/soft_u2f_v2.py
+++ b/test/soft_u2f_v2.py
@@ -112,9 +112,7 @@ class SoftU2FDevice(object):
             CERT_PRIV, password=None, backend=default_backend())
         cert = CERT
         data = b'\x00' + app_param + client_param + key_handle + pub_key
-        signer = cert_priv.signer(ec.ECDSA(hashes.SHA256()))
-        signer.update(data)
-        signature = signer.finalize()
+        signature = cert_priv.sign(data, ec.ECDSA(hashes.SHA256()))
 
         raw_response = (b'\x05' + pub_key + six.int2byte(len(key_handle)) +
                         key_handle + cert + signature)
@@ -163,9 +161,7 @@ class SoftU2FDevice(object):
         counter = struct.pack('>I', self.counter)
 
         data = app_param + touch + counter + client_param
-        signer = priv_key.signer(ec.ECDSA(hashes.SHA256()))
-        signer.update(data)
-        signature = signer.finalize()
+        signature = priv_key.sign(data, ec.ECDSA(hashes.SHA256()))
         raw_response = touch + counter + signature
 
         return SignResponse(
diff --git a/u2flib_server/attestation/resolvers.py b/u2flib_server/attestation/resolvers.py
index 034549f..cd59b10 100644
--- a/u2flib_server/attestation/resolvers.py
+++ b/u2flib_server/attestation/resolvers.py
@@ -86,27 +86,29 @@ class MetadataResolver(object):
         cert_bytes = cert.tbs_certificate_bytes
 
         if isinstance(pubkey, rsa.RSAPublicKey):
-            verifier = pubkey.verifier(
-                cert_signature,
-                padding.PKCS1v15(),
-                cert.signature_hash_algorithm
-            )
+            try:
+                pubkey.verify(
+                    cert_signature,
+                    cert_bytes,
+                    padding.PKCS1v15(),
+                    cert.signature_hash_algorithm
+                )
+                return True
+            except InvalidSignature:
+                return False
         elif isinstance(pubkey, ec.EllipticCurvePublicKey):
-            verifier = pubkey.verifier(
-                cert_signature,
-                ec.ECDSA(cert.signature_hash_algorithm)
-            )
+            try:
+                pubkey.verify(
+                    cert_signature,
+                    cert_bytes,
+                    ec.ECDSA(cert.signature_hash_algorithm)
+                )
+                return True
+            except InvalidSignature:
+                return False
         else:
             raise ValueError("Unsupported public key value")
 
-        verifier.update(cert_bytes)
-
-        try:
-            verifier.verify()
-            return True
-        except InvalidSignature:
-            return False
-
     def resolve(self, cert):
         if isinstance(cert, bytes):
             cert = x509.load_der_x509_certificate(cert, default_backend())
diff --git a/u2flib_server/model.py b/u2flib_server/model.py
index 481be51..6ec01bb 100644
--- a/u2flib_server/model.py
+++ b/u2flib_server/model.py
@@ -175,12 +175,9 @@ class RegistrationData(object):
         cert = x509.load_der_x509_certificate(self.certificate,
                                               default_backend())
         pubkey = cert.public_key()
-        verifier = pubkey.verifier(self.signature, ec.ECDSA(hashes.SHA256()))
-
-        verifier.update(b'\0' + app_param + chal_param + self.key_handle +
-                        self.pub_key)
+        msg = (b'\0' + app_param + chal_param + self.key_handle + self.pub_key)
         try:
-            verifier.verify()
+            pubkey.verify(self.signature, msg, ec.ECDSA(hashes.SHA256()))
         except InvalidSignature:
             raise ValueError('Attestation signature is invalid')
 
@@ -207,13 +204,9 @@ class SignatureData(object):
     def verify(self, app_param, chal_param, der_pubkey):
         pubkey = load_der_public_key(PUB_KEY_DER_PREFIX + der_pubkey,
                                      default_backend())
-        verifier = pubkey.verifier(self.signature, ec.ECDSA(hashes.SHA256()))
-        verifier.update(app_param +
-                        six.int2byte(self.user_presence) +
-                        struct.pack('>I', self.counter) +
-                        chal_param)
+        msg = app_param + six.int2byte(self.user_presence) + struct.pack('>I', self.counter) + chal_param
         try:
-            verifier.verify()
+            pubkey.verify(self.signature, msg, ec.ECDSA(hashes.SHA256()))
         except InvalidSignature:
             raise ValueError('U2F signature is invalid')