diff --git a/pySim/ota.py b/pySim/ota.py
new file mode 100644
index 0000000..bc4b0a7
--- /dev/null
+++ b/pySim/ota.py
@@ -0,0 +1,443 @@
+"""Code related to SIM/UICC OTA according to TS 102 225 + TS 31.115."""
+
+# (C) 2021-2022 by Harald Welte <laforge@osmocom.org>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from pySim.construct import *
+from pySim.utils import b2h
+from pySim.sms import UserDataHeader
+from construct import *
+import zlib
+import abc
+import struct
+from typing import Optional
+
+# ETS TS 102 225 gives the general command structure and the dialects for CAT_TP, TCP/IP and HTTPS
+# 3GPP TS 31.115 gives the dialects for SMS-PP, SMS-CB, USSD and HTTP
+
+# CPI CPL CHI CHL SPI KIc KID TAR CNTR PCNTR RC/CC/DS data
+
+#                                           CAT_TP  TCP/IP          SMS
+# CPI                                       0x01    0x01            =IEIa=70,len=0
+# CHI                                       NULL    NULL            NULL
+# CPI, CPL and CHL included in RC/CC/DS     true    true
+# RPI                                       0x02    0x02            =IEIa=71,len=0
+# RHI                                       NULL    NULL
+# RPI, RPL and RHL included in RC/CC/DS     true    true
+# packet-id                             0-bf,ff     0-bf,ff
+# identification packet                     false   102 225 tbl 6
+
+# KVN 1..f; KI1=KIc, KI2=KID, KI3=DEK
+
+# ETSI TS 102 225 Table 5 + 3GPP TS 31.115 Section 7
+ResponseStatus = Enum(Int8ub, por_ok=0, rc_cc_ds_failed=1, cntr_low=2, cntr_high=3,
+                      cntr_blocked=4, ciphering_error=5, undefined_security_error=6,
+                      insufficient_memory=7, more_time_needed=8, tar_unknown=9,
+                      insufficient_security_level=0x0A,
+                      actual_response_sms_submit=0x0B,
+                      actual_response_ussd=0x0C)
+
+# ETSI TS 102 226 Section 5.1.2
+CompactRemoteResp = Struct('number_of_commands'/Int8ub,
+                           'last_status_word'/HexAdapter(Bytes(2)),
+                           'last_response_data'/HexAdapter(GreedyBytes))
+
+RC_CC_DS = Enum(BitsInteger(2), no_rc_cc_ds=0, rc=1, cc=2, ds=3)
+
+# TS 102 225 Section 5.1.1 + TS 31.115 Section 4.2
+SPI = BitStruct(  # first octet
+    Padding(3),
+    'counter'/Enum(BitsInteger(2), no_counter=0, counter_no_replay_or_seq=1,
+                   counter_must_be_higher=2, counter_must_be_lower=3),
+    'ciphering'/Flag,
+    'rc_cc_ds'/RC_CC_DS,
+    # second octet
+    Padding(2),
+    'por_in_submit'/Flag,
+    'por_shall_be_ciphered'/Flag,
+    'por_rc_cc_ds'/RC_CC_DS,
+    'por'/Enum(BitsInteger(2), no_por=0,
+               por_required=1, por_only_when_error=2)
+)
+
+# TS 102 225 Section 5.1.2
+KIC = BitStruct('key'/BitsInteger(4),
+                'algo'/Enum(BitsInteger(4), implicit=0, single_des=1, triple_des_cbc2=5, triple_des_cbc3=9,
+                            aes_cbc=2)
+                )
+
+# TS 102 225 Section 5.1.3.1
+KID_CC = BitStruct('key'/BitsInteger(4),
+                   'algo'/Enum(BitsInteger(4), implicit=0, single_des=1, triple_des_cbc2=5, triple_des_cbc3=9,
+                               aes_cmac=2)
+                   )
+
+# TS 102 225 Section 5.1.3.2
+KID_RC = BitStruct('key'/BitsInteger(4),
+                   'algo'/Enum(BitsInteger(4), implicit=0, crc16=1, crc32=5, proprietary=3)
+                   )
+
+SmsCommandPacket = Struct('cmd_pkt_len'/Int16ub,
+                          'cmd_hdr_len'/Int8ub,
+                          'spi'/SPI,
+                          'kic'/KIC,
+                          'kid'/Switch(this.spi.rc_cc_ds, {'cc': KID_CC, 'rc': KID_RC }),
+                          'tar'/Bytes(3),
+                          'secured_data'/GreedyBytes)
+
+class OtaKeyset:
+    """The OTA related data (key material, counter) to be used in encrypt/decrypt."""
+    def __init__(self, algo_crypt: str, kic_idx: int, kic: bytes,
+                 algo_auth: str, kid_idx: int, kid: bytes, cntr: int = 0):
+        self.algo_crypt = algo_crypt
+        self.kic = bytes(kic)
+        self.kic_idx = kic_idx
+        self.algo_auth = algo_auth
+        self.kid = bytes(kid)
+        self.kid_idx = kid_idx
+        self.cntr = cntr
+
+    @property
+    def auth(self):
+        """Return an instance of the matching OtaAlgoAuth."""
+        return OtaAlgoAuth.fromKeyset(self)
+
+    @property
+    def crypt(self):
+        """Return an instance of the matching OtaAlgoCrypt."""
+        return OtaAlgoCrypt.fromKeyset(self)
+
+class OtaCheckError(Exception):
+    pass
+
+class OtaDialect(abc.ABC):
+    """Base Class for OTA dialects such as SMS, BIP, ..."""
+
+    def _compute_sig_len(self, spi:SPI):
+        if spi['rc_cc_ds'] == 'no_rc_cc_ds':
+            return 0
+        elif spi['rc_cc_ds'] == 'rc': # CRC-32
+            return 4
+        elif spi['rc_cc_ds'] == 'cc': # Cryptographic Checksum (CC)
+            # TODO: this is not entirely correct, as in AES case it could be 4 or 8
+            return 8
+        else:
+            raise ValueError("Invalid rc_cc_ds: %s" % spi['rc_cc_ds'])
+
+    @abc.abstractmethod
+    def encode_cmd(self, otak: OtaKeyset, tar: bytes, apdu: bytes) -> bytes:
+        pass
+
+    @abc.abstractmethod
+    def decode_resp(self, otak: OtaKeyset, apdu: bytes) -> (object, Optional["CompactRemoteResp"]):
+        """Decode a response into a response packet and, if indicted (by a
+        response status of `"por_ok"`) a decoded response.
+
+        The response packet's common characteristics are not fully determined,
+        and (so far) completely proprietary per dialect."""
+        pass
+
+
+from Crypto.Cipher import DES, DES3, AES
+from Crypto.Hash import CMAC
+
+class OtaAlgo(abc.ABC):
+    iv = b'\x00\x00\x00\x00\x00\x00\x00\x00'
+    blocksize = None
+    enum_name = None
+
+    @staticmethod
+    def _get_padding(in_len: int, multiple: int, padding: int = 0):
+        """Return padding bytes towards multiple of N."""
+        if in_len % multiple == 0:
+            return b''
+        pad_cnt = multiple - (in_len % multiple)
+        return b'\x00' * pad_cnt
+
+    @staticmethod
+    def _pad_to_multiple(indat: bytes, multiple: int, padding: int = 0):
+        """Pad input bytes to multiple of N."""
+        return indat + OtaAlgo._get_padding(len(indat), multiple, padding)
+
+    def pad_to_blocksize(self, indat: bytes, padding: int = 0):
+        """Pad the given input data to multiple of the cipher block size."""
+        return self._pad_to_multiple(indat, self.blocksize, padding)
+
+    def __init__(self, otak: OtaKeyset):
+        self.otak = otak
+
+    def __str__(self):
+        return self.__class__.__name__
+
+class OtaAlgoCrypt(OtaAlgo, abc.ABC):
+    def __init__(self, otak: OtaKeyset):
+        if self.enum_name != otak.algo_crypt:
+            raise ValueError('Cannot use algorithm %s with key for %s' % (self.enum_name, otak.algo_crypt))
+        super().__init__(otak)
+
+    def encrypt(self, data:bytes) -> bytes:
+        """Encrypt given input bytes using the key material given in constructor."""
+        padded_data = self.pad_to_blocksize(data)
+        return self._encrypt(data)
+
+    def decrypt(self, data:bytes) -> bytes:
+        """Decrypt given input bytes using the key material given in constructor."""
+        return self._decrypt(data)
+
+    @abc.abstractmethod
+    def _encrypt(self, data:bytes) -> bytes:
+        """Actual implementation, to be implemented by derived class."""
+        pass
+
+    @abc.abstractmethod
+    def _decrypt(self, data:bytes) -> bytes:
+        """Actual implementation, to be implemented by derived class."""
+        pass
+
+    @classmethod
+    def fromKeyset(cls, otak: OtaKeyset) -> 'OtaAlgoCrypt':
+        """Resolve the class for the encryption algorithm of otak and instantiate it."""
+        for subc in cls.__subclasses__():
+            if subc.enum_name == otak.algo_crypt:
+                return subc(otak)
+        raise ValueError('No implementation for crypt algorithm %s' % otak.algo_auth)
+
+class OtaAlgoAuth(OtaAlgo, abc.ABC):
+    def __init__(self, otak: OtaKeyset):
+        if self.enum_name != otak.algo_auth:
+            raise ValueError('Cannot use algorithm %s with key for %s' % (self.enum_name, otak.algo_crypt))
+        super().__init__(otak)
+
+    def sign(self, data:bytes) -> bytes:
+        """Compute the CC/CR check bytes for the input data using key material
+        given in constructor."""
+        padded_data = self.pad_to_blocksize(data)
+        sig = self._sign(padded_data)
+        return sig
+
+    def check_sig(self, data:bytes, cc_received:bytes):
+        """Compute the CC/CR check bytes for the input data and compare against cc_received."""
+        cc = self.sign(data)
+        if cc_received != cc:
+            raise OtaCheckError('Received CC (%s) != Computed CC (%s)' % (b2h(cc_received), b2h(cc)))
+
+    @abc.abstractmethod
+    def _sign(self, data:bytes) -> bytes:
+        """Actual implementation, to be implemented by derived class."""
+        pass
+
+    @classmethod
+    def fromKeyset(cls, otak: OtaKeyset) -> 'OtaAlgoAuth':
+        """Resolve the class for the authentication algorithm of otak and instantiate it."""
+        for subc in cls.__subclasses__():
+            if subc.enum_name == otak.algo_auth:
+                return subc(otak)
+        raise ValueError('No implementation for auth algorithm %s' % otak.algo_auth)
+
+class OtaAlgoCryptDES(OtaAlgoCrypt):
+    """DES is insecure.  For backwards compatibility with pre-Rel8"""
+    name = 'DES'
+    enum_name = 'single_des'
+    blocksize = 8
+    def _encrypt(self, data:bytes) -> bytes:
+        cipher = DES.new(self.otak.kic, DES.MODE_CBC, self.iv)
+        return cipher.encrypt(data)
+
+    def _decrypt(self, data:bytes) -> bytes:
+        cipher = DES.new(self.otak.kic, DES.MODE_CBC, self.iv)
+        return cipher.decrypt(data)
+
+class OtaAlgoAuthDES(OtaAlgoAuth):
+    """DES is insecure.  For backwards compatibility with pre-Rel8"""
+    name = 'DES'
+    enum_name = 'single_des'
+    blocksize = 8
+    def _sign(self, data:bytes) -> bytes:
+        cipher = DES.new(self.otak.kid, DES.MODE_CBC, self.iv)
+        ciph = cipher.encrypt(data)
+        return ciph[len(ciph) - 8:]
+
+class OtaAlgoCryptDES3(OtaAlgoCrypt):
+    name = '3DES'
+    enum_name = 'triple_des_cbc2'
+    blocksize = 8
+    def _encrypt(self, data:bytes) -> bytes:
+        cipher = DES3.new(self.otak.kic, DES3.MODE_CBC, self.iv)
+        return cipher.encrypt(data)
+
+    def _decrypt(self, data:bytes) -> bytes:
+        cipher = DES3.new(self.otak.kic, DES3.MODE_CBC, self.iv)
+        return cipher.decrypt(data)
+
+class OtaAlgoAuthDES3(OtaAlgoAuth):
+    name = '3DES'
+    enum_name = 'triple_des_cbc2'
+    blocksize = 8
+    def _sign(self, data:bytes) -> bytes:
+        cipher = DES3.new(self.otak.kid, DES3.MODE_CBC, self.iv)
+        ciph = cipher.encrypt(data)
+        return ciph[len(ciph) - 8:]
+
+class OtaAlgoCryptAES(OtaAlgoCrypt):
+    name = 'AES'
+    enum_name = 'aes_cbc'
+    blocksize = 16 # TODO: is this needed?
+    def _encrypt(self, data:bytes) -> bytes:
+        cipher = AES.new(self.otak.kic, AES.MODE_CBC, self.iv)
+        return cipher.encrypt(data)
+
+    def _decrypt(self, data:bytes) -> bytes:
+        cipher = AES.new(self.otak.kic, AES.MODE_CBC, self.iv)
+        return cipher.decrypt(data)
+
+class OtaAlgoAuthAES(OtaAlgoAuth):
+    name = 'AES'
+    enum_name = 'aes_cmac'
+    blocksize = 16 # TODO: is this needed?
+    def _sign(self, data:bytes) -> bytes:
+        cmac = CMAC.new(self.otak.kid, ciphermod=AES, mac_len=8)
+        cmac.update(data)
+        ciph = cmac.digest()
+        return ciph[len(ciph) - 8:]
+
+
+
+class OtaDialectSms(OtaDialect):
+    """OTA dialect for SMS based transport, as described in 3GPP TS 31.115."""
+    SmsResponsePacket = Struct('rpl'/Int16ub,
+                               'rhl'/Int8ub,
+                               'tar'/Bytes(3),
+                               'cntr'/Bytes(5),
+                               'pcntr'/Int8ub,
+                               'response_status'/ResponseStatus,
+                               'cc_rc'/Bytes(this.rhl-10),
+                               'secured_data'/GreedyBytes)
+
+    def encode_cmd(self, otak: OtaKeyset, tar: bytes, spi: dict, apdu: bytes) -> bytes:
+        # length of signature in octets
+        len_sig = self._compute_sig_len(spi)
+        pad_cnt = 0
+        if spi['ciphering']: # ciphering is requested
+            # append padding bytes to end up with blocksize
+            len_cipher = 6 + len_sig + len(apdu)
+            padding = otak.crypt._get_padding(len_cipher, otak.crypt.blocksize)
+            pad_cnt = len(padding)
+            apdu += padding
+
+        kic = {'key': otak.kic_idx, 'algo': otak.algo_crypt}
+        kid = {'key': otak.kid_idx, 'algo': otak.algo_auth}
+
+        # CHL = number of octets from (and including) SPI to the end of RC/CC/DS
+        # 13 == SPI(2) + KIc(1) + KId(1) + TAR(3) + CNTR(5) + PCNTR(1)
+        chl = 13 + len_sig
+
+        # CHL + SPI (+ KIC + KID)
+        c = Struct('chl'/Int8ub, 'spi'/SPI, 'kic'/KIC, 'kid'/KID_CC, 'tar'/Bytes(3))
+        part_head = c.build({'chl': chl, 'spi':spi, 'kic':kic, 'kid':kid, 'tar':tar})
+        #print("part_head: %s" % b2h(part_head))
+
+        # CNTR + PCNTR (CNTR not used)
+        part_cnt = otak.cntr.to_bytes(5, 'big') + pad_cnt.to_bytes(1, 'big')
+        #print("part_cnt: %s" % b2h(part_cnt))
+
+        envelope_data = part_head + part_cnt + apdu
+        #print("envelope_data: %s" % b2h(envelope_data))
+
+        # 2-byte CPL. CPL is part of RC/CC/CPI to end of secured data, including any padding for ciphering
+        # CPL from and including CPI to end of secured data, including any padding for ciphering
+        cpl = len(envelope_data) + len_sig
+        envelope_data = cpl.to_bytes(2, 'big') + envelope_data
+        #print("envelope_data with cpl: %s" % b2h(envelope_data))
+
+        if spi['rc_cc_ds'] == 'cc':
+            cc = otak.auth.sign(envelope_data)
+            envelope_data = part_cnt + cc + apdu
+        elif spi['rc_cc_ds'] == 'rc':
+            # CRC32
+            crc32 = zlib.crc32(envelope_data) & 0xffffffff
+            envelope_data = part_cnt + crc32.to_bytes(4, 'big') + apdu
+        elif spi['rc_cc_ds'] == 'no_rc_cc_ds':
+            envelope_data = part_cnt + apdu
+        else:
+            raise ValueError("Invalid rc_cc_ds: %s" % spi['rc_cc_ds'])
+
+        #print("envelope_data with sig: %s" % b2h(envelope_data))
+
+        # encrypt as needed
+        if spi['ciphering']: # ciphering is requested
+            ciph = otak.crypt.encrypt(envelope_data)
+            envelope_data = part_head + ciph
+            # prefix with another CPL
+            cpl = len(envelope_data)
+            envelope_data = cpl.to_bytes(2, 'big') + envelope_data
+        else:
+            envelope_data = part_head + envelope_data
+
+        #print("envelope_data: %s" % b2h(envelope_data))
+
+        return envelope_data
+
+    def decode_resp(self, otak: OtaKeyset, spi: dict, data: bytes) -> ("OtaDialectSms.SmsResponsePacket", Optional["CompactRemoteResp"]):
+        if isinstance(data, str):
+            data = h2b(data)
+        # plain-text POR:   027100000e0ab000110000000000000001612f
+        # UDHL RPI IEDLa  RPL  RHL TAR    CNTR       PCNTR STS
+        # 02   71  00     000e 0a  b00011 0000000000 00    00  01 612f
+        # POR with CC:      027100001612b000110000000000000055f47118381175fb01612f
+        # POR with CC+CIPH: 027100001c12b000119660ebdb81be189b5e4389e9e7ab2bc0954f963ad869ed7c
+        if data[0] != 0x02:
+            raise ValueError('Unexpected UDL=0x%02x' % data[0])
+        udhd, remainder = UserDataHeader.fromBytes(data)
+        if not udhd.has_ie(0x71):
+            raise ValueError('RPI 0x71 not found in UDH')
+        rph_rhl_tar = remainder[:6] # RPH+RHL+TAR; not ciphered
+        res = self.SmsResponsePacket.parse(remainder)
+
+        if spi['por_shall_be_ciphered']:
+            # decrypt
+            ciphered_part = remainder[6:]
+            deciph = otak.crypt.decrypt(ciphered_part)
+            temp_data = rph_rhl_tar + deciph
+            res = self.SmsResponsePacket.parse(temp_data)
+            # remove specified number of padding bytes, if any
+            if res['pcntr'] != 0:
+                # this conditional is needed as python [:-0] renders an empty return!
+                res['secured_data'] = res['secured_data'][:-res['pcntr']]
+            remainder = temp_data
+
+        # is there a CC/RC present?
+        len_sig = res['rhl'] - 10
+        if spi['por_rc_cc_ds'] == 'no_rc_cc_ds':
+            if len_sig:
+                raise OtaCheckError('No RC/CC/DS requested, but len_sig=%u' % len_sig)
+        elif spi['por_rc_cc_ds'] == 'cc':
+            # verify signature
+            # UDH is part of CC/RC!
+            udh = data[:3]
+            # RPL, RHL, TAR, CNTR, PCNTR and STSare part of CC/RC
+            rpl_rhl_tar_cntr_pcntr_sts = remainder[:13]
+            # remove the CC/RC bytes
+            temp_data = udh + rpl_rhl_tar_cntr_pcntr_sts + remainder[13+len_sig:]
+            otak.auth.check_sig(temp_data, res['cc_rc'])
+        # TODO: CRC
+        else:
+            raise OtaCheckError('Unknown por_rc_cc_ds: %s' % spi['por_rc_cc_ds'])
+
+        # TODO: ExpandedRemoteResponse according to TS 102 226 5.2.2
+        if res.response_status == 'por_ok':
+            dec = CompactRemoteResp.parse(res['secured_data'])
+        else:
+            dec = None
+        return (res, dec)
diff --git a/pySim/sms.py b/pySim/sms.py
new file mode 100644
index 0000000..a281213
--- /dev/null
+++ b/pySim/sms.py
@@ -0,0 +1,53 @@
+"""Code related to SMS Encoding/Decoding"""
+# simplistic SMS T-PDU code, as unfortunately nobody bothered to port the python smspdu
+# module to python3, and I gave up after >= 3 hours of trying and failing to do so
+
+# (C) 2022 by Harald Welte <laforge@osmocom.org>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import typing
+from construct import Int8ub, Bytes
+from construct import Struct, Tell, this, RepeatUntil
+
+from pySim.utils import Hexstr, h2b, b2h
+
+BytesOrHex = typing.Union[Hexstr, bytes]
+
+class UserDataHeader:
+    # a single IE in the user data header
+    ie_c = Struct('offset'/Tell, 'iei'/Int8ub, 'length'/Int8ub, 'data'/Bytes(this.length))
+    # parser for the full UDH: Length octet followed by sequence of IEs
+    _construct = Struct('udhl'/Int8ub,
+                        # FIXME: somehow the below lambda is not working, we always only get the first IE?
+                        'ies'/RepeatUntil(lambda obj,lst,ctx: ctx._io.tell() > 1+this.udhl, ie_c))
+
+    def __init__(self, ies=[]):
+        self.ies = ies
+
+    def __repr__(self) -> str:
+        return 'UDH(%r)' % self.ies
+
+    def has_ie(self, iei:int) -> bool:
+        for ie in self.ies:
+            if ie['iei'] == iei:
+                return True
+        return False
+
+    @classmethod
+    def fromBytes(cls, inb: BytesOrHex) -> typing.Tuple['UserDataHeader', bytes]:
+        if isinstance(inb, str):
+            inb = h2b(inb)
+        res = cls._construct.parse(inb)
+        return cls(res['ies']), inb[1+res['udhl']:]
diff --git a/requirements.txt b/requirements.txt
index 4f037da..4144a1c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -9,3 +9,4 @@
 pyyaml>=5.1
 termcolor
 colorlog
+pycryptodome
diff --git a/setup.py b/setup.py
index b9ad1bf..4c257a0 100644
--- a/setup.py
+++ b/setup.py
@@ -18,7 +18,8 @@
         "bidict",
         "gsm0338",
         "termcolor",
-        "colorlog"
+        "colorlog",
+        "pycryptodome"
     ],
     scripts=[
         'pySim-prog.py',
diff --git a/tests/test_ota.py b/tests/test_ota.py
new file mode 100644
index 0000000..277f178
--- /dev/null
+++ b/tests/test_ota.py
@@ -0,0 +1,85 @@
+#!/usr/bin/env python3
+
+import unittest
+from pySim.utils import h2b, b2h
+from pySim.ota import *
+
+class Test_SMS_3DES(unittest.TestCase):
+    tar = h2b('b00000')
+    """Test the OtaDialectSms for 3DES algorithms."""
+    def __init__(self, foo, **kwargs):
+        super().__init__(foo, **kwargs)
+        # KIC1 + KID1 of 8988211000000467285
+        KIC1 = h2b('D0FDA31990D8D64178601317191669B4')
+        KID1 = h2b('D24EB461799C5E035C77451FD9404463')
+        KIC3 = h2b('C21DD66ACAC13CB3BC8B331B24AFB57B')
+        KID3 = h2b('12110C78E678C25408233076AA033615')
+        self.od = OtaKeyset(algo_crypt='triple_des_cbc2', kic_idx=3, kic=KIC3,
+                            algo_auth='triple_des_cbc2', kid_idx=3, kid=KID3)
+        self.dialect = OtaDialectSms()
+        self.spi_base = {
+                'counter':'no_counter',
+                'ciphering': True,
+                'rc_cc_ds': 'cc',
+                'por_in_submit':False,
+                'por': 'por_required',
+                'por_shall_be_ciphered': True,
+                'por_rc_cc_ds': 'cc',
+            }
+
+    def _check_response(self, r, d):
+        self.assertEqual(d['number_of_commands'], 1)
+        self.assertEqual(d['last_status_word'], '612f')
+        self.assertEqual(d['last_response_data'], u'')
+        self.assertEqual(r['response_status'], 'por_ok')
+
+    def test_resp_3des_ciphered(self):
+        spi = self.spi_base
+        spi['por_shall_be_ciphered'] = True
+        spi['por_rc_cc_ds'] = 'cc'
+        r, d = self.dialect.decode_resp(self.od, spi, '027100001c12b000119660ebdb81be189b5e4389e9e7ab2bc0954f963ad869ed7c')
+        self._check_response(r, d)
+
+    def test_resp_3des_signed(self):
+        spi = self.spi_base
+        spi['por_shall_be_ciphered'] = False
+        spi['por_rc_cc_ds'] = 'cc'
+        r, d = self.dialect.decode_resp(self.od, spi, '027100001612b000110000000000000055f47118381175fb01612f')
+        self._check_response(r, d)
+
+    def test_resp_3des_signed_err(self):
+        """Expect an OtaCheckError exception if the computed CC != received CC"""
+        spi = self.spi_base
+        spi['por_shall_be_ciphered'] = False
+        spi['por_rc_cc_ds'] = 'cc'
+        with self.assertRaises(OtaCheckError) as context:
+            r, d = self.dialect.decode_resp(self.od, spi, '027100001612b000110000000000000055f47118381175fb02612f')
+        self.assertTrue('!= Computed CC' in str(context.exception))
+
+    def test_resp_3des_none(self):
+        spi = self.spi_base
+        spi['por_shall_be_ciphered'] = False
+        spi['por_rc_cc_ds'] = 'no_rc_cc_ds'
+        r, d = self.dialect.decode_resp(self.od, spi, '027100000e0ab000110000000000000001612f')
+        self._check_response(r, d)
+
+    def test_cmd_3des_ciphered(self):
+        spi = self.spi_base
+        spi['ciphering'] = True
+        spi['rc_cc_ds'] = 'no_rc_cc_ds'
+        r = self.dialect.encode_cmd(self.od, self.tar, spi, h2b('00a40000023f00'))
+        self.assertEqual(b2h(r), '00180d04193535b00000e3ec80a849b554421276af3883927c20')
+
+    def test_cmd_3des_signed(self):
+        spi = self.spi_base
+        spi['ciphering'] = False
+        spi['rc_cc_ds'] = 'cc'
+        r = self.dialect.encode_cmd(self.od, self.tar, spi, h2b('00a40000023f00'))
+        self.assertEqual(b2h(r), '1502193535b00000000000000000072ea17bdb72060e00a40000023f00')
+
+    def test_cmd_3des_none(self):
+        spi = self.spi_base
+        spi['ciphering'] = False
+        spi['rc_cc_ds'] = 'no_rc_cc_ds'
+        r = self.dialect.encode_cmd(self.od, self.tar, spi, h2b('00a40000023f00'))
+        self.assertEqual(b2h(r), '0d00193535b0000000000000000000a40000023f00')