diff --git a/scapy/layers/ntp.py b/scapy/layers/ntp.py
index 53743f9acdd..0f668e9f2fa 100644
--- a/scapy/layers/ntp.py
+++ b/scapy/layers/ntp.py
@@ -213,41 +213,57 @@ def mysummary(self):
         return self.sprintf("NTP v%ir,NTP.version%, %NTP.mode%")
 
 
-class _NTPAuthenticatorPaddingField(StrField):
-    """
-    StrField handling the padding that may be found before the
-    "authenticator" field.
-    """
-
-    def getfield(self, pkt, s):
-        ret = None
-        remain = s
-        length = len(s)
-
-        if length > _NTP_AUTH_MD5_TAIL_SIZE:
-            start = length - _NTP_AUTH_MD5_TAIL_SIZE
-            ret = s[:start]
-            remain = s[start:]
-        return remain, ret
-
-
 class NTPAuthenticator(Packet):
     """
     Packet handling the "authenticator" part of a NTP packet, as
     defined in RFC 5905.
     """
+    authenticator_length = 16  # MD5
+    padding = b""
 
     name = "Authenticator"
     fields_desc = [
-        _NTPAuthenticatorPaddingField("padding", ""),
         IntField("key_id", 0),
-        XStrFixedLenField("dgst", "", length_from=lambda x: 16)
+        XStrFixedLenField("dgst", "", length_from=lambda x: x.authenticator_length)
     ]
 
     def extract_padding(self, s):
         return b"", s
 
 
+class NTPAuthenticatorMD5(NTPAuthenticator):
+    pass
+
+
+class NTPAuthenticatorSHA1(NTPAuthenticator):
+    authenticator_length = 20
+
+
+class NTPAuthenticatorSHA256(NTPAuthenticator):
+    authenticator_length = 32
+
+
+class NTPAuthenticatorSHA512(NTPAuthenticator):
+    authenticator_length = 64
+
+
+def _guess_authenticator_class(payload):
+    """
+    Attempt to guess the NTP Authenticator class using the payload length
+    """
+    plen = len(payload)
+
+    authenticator_dispatch = {16: NTPAuthenticatorMD5,
+                              20: NTPAuthenticatorSHA1,
+                              32: NTPAuthenticatorSHA256,
+                              64: NTPAuthenticatorSHA512}
+    authenticator_length = plen - 4
+    authenticator_class = authenticator_dispatch.get(authenticator_length,
+                                                     None)
+
+    return authenticator_class
+
+
 class NTPExtension(Packet):
     """
     Packet handling a NTPv4 extension.
@@ -450,12 +466,14 @@ class NTPHeader(NTP):
 
     def guess_payload_class(self, payload):
         """
-        Handles NTPv4 extensions and MAC part (when authentication is used.)
+        Handles NTPv4 extensions and MAC part (when authentication is used)
         """
+
         plen = len(payload)
+        authenticator_class = _guess_authenticator_class(payload)
 
-        if plen - 4 in [16, 20, 32, 64]:  # length of MD5, SHA1, SHA256, SHA512
-            return NTPAuthenticator
+        if authenticator_class is not None:
+            return authenticator_class
         elif plen > _NTP_AUTH_MD5_TAIL_SIZE:
             return NTPExtensions
 
@@ -810,7 +828,6 @@ class NTPControl(NTP):
         ShortField("count", None),
         NTPControlDataPacketLenField(
             "data", "", Packet, length_from=lambda p: p.count),
-        PacketField("authenticator", "", NTPAuthenticator),
     ]
 
     def post_build(self, p, pay):
@@ -821,6 +838,18 @@ def post_build(self, p, pay):
             p = p[:11] + struct.pack("!H", length) + p[13:]
         return p + pay
 
+    def extract_padding(self, s):
+        # Check the 64 bit alignement
+        padding_length = len(self.raw_packet_cache) % 8 * 8
+        if padding_length == 0:
+            return b"", s
+
+        padding_length -= len(self.raw_packet_cache)
+        return s[padding_length:], s[:padding_length]
+
+    def guess_payload_class(self, s):
+        return _guess_authenticator_class(s)
+
 
 ##############################################################################
 #     Private (mode 7)
diff --git a/test/scapy/layers/ntp.uts b/test/scapy/layers/ntp.uts
index 7a939bfdadd..fe1e41614ff 100644
--- a/test/scapy/layers/ntp.uts
+++ b/test/scapy/layers/ntp.uts
@@ -99,7 +99,7 @@ assert p.stratum == 2
 
 s = hex_bytes("000c2962f268d094666d23750800450000640db640004011a519c0a80364c0a80305a51e007b0050731a2300072000000000000000000000000000000000000000000000000000000000000000000000000052c7bc1dda64b97d0000000bcdc3825dbf6b7ad02886ff45aa8b2eaf7ac78bc1")
 p = Ether(s)
-assert NTPAuthenticator in p and p[NTPAuthenticator].key_id == 3452142173
+assert NTPAuthenticator in p and p[NTPAuthenticator].key_id == 11
 
 
 ############
@@ -309,7 +309,7 @@ assert bytes_hex(p.authenticator.dgst) == b'bfa6d85ff96d1e326c293caceec2a539'
 
 
 = NTP Control (mode 6) - CTL_OP_SAVECONFIG (1) - request
-s = b'\x16\t\x00\x1d\x00\x00\x00\x00\x00\x00\x00\x0fntp.test.2.conf\x00\x00\x00\x00\x00\x00\x00\x00\x01\xc9\xfb\x8a\xbe<`_\xfa6\xd2\x18\xc3\xb7d\x89#'
+s = b'\x16\t\x00\x1d\x00\x00\x00\x00\x00\x00\x00\x0fntp.test.2.conf\x00\x00\x00\x00\x00\x00\x00\x00\x01\xc9\xfb\x8a\xbe<`_\xfa6\xd2\x18\xc3\xb7d'
 p = NTP(s)
 assert isinstance(p, NTPControl)
 assert p.version == 2
@@ -321,7 +321,7 @@ assert p.op_code == 9
 assert p.count == 15
 assert p.data.load == b'ntp.test.2.conf\x00'
 assert p.authenticator.key_id == 1
-assert bytes_hex(p.authenticator.dgst) == b'c9fb8abe3c605ffa36d218c3b7648923'
+assert bytes_hex(p.authenticator.dgst) == b'c9fb8abe3c605ffa36d218c3b764'
 
 
 = NTP Control (mode 6) - CTL_OP_SAVECONFIG (2) - response
@@ -1144,4 +1144,15 @@ raw_pkt = (b"#\x02\n\xec\x00\x00\x00\x00\x00\x00\xf2\xce\x7f\x00\x00\x01\x00"
            b"\x00\x00\x00\x00\x00\x00\x00\xe6}gt\x00\x00\x00\x00\xe6}gt\x00"
            b"\x00\x00\x00\xe6}gt\x00\x00\x00\x00")
 
+
 assert raw(pkt_1) == raw(pkt_2) == raw_pkt
+
+############
+############
++ Hash Algorithms Tests
+
+= SHA1
+
+r = b'\x00\x0c)\xd3\x93W\x00\x0c)b\xf2h\x08\x00E\xb8\x00d\x9f\xd3@\x00@\x11\x12\xa7\xc0\xa8\x03\x05\xc0\xa8\x03\x01\x00{\x00{\x00P\xdb;\xe3\x00\x06\xe8\x00\x00\x00\x00\x00\x00\x00\x00INIT\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xe2\x81a(H\xca\x0e\xf4\x00\x00\x00\x0c\xd2\x05\x98\x88\xb4\xa2\xad\xc1\x1d-\xbd\x14 \xa45`\xbf\x92\xc6\xf9'
+p = Ether(r)
+assert NTP in p and p.key_id == 12 and p.dgst == b"d2059888b4a2adc11d2dbd1420a43560bf92c6f9"