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Versions: (draft-mattsson-core-security-overhead) 00 01 draft-ietf-lwig-security-protocol-comparison

Network Working Group                                        J. Mattsson
Internet-Draft                                              F. Palombini
Intended status: Informational                               Ericsson AB
Expires: September 20, 2018                               March 19, 2018


                 Comparison of CoAP Security Protocols
          draft-mattsson-lwig-security-protocol-comparison-01

Abstract

   This document analyzes and compares per-packet message size overheads
   when using different security protocols to secure CoAP.  The analyzed
   security protocols are DTLS 1.2, DTLS 1.3, TLS 1.2, TLS 1.3, and
   OSCORE.  DTLS and TLS are analyzed with and without 6LoWPAN-GHC
   compression.  DTLS is analyzed with and without Connection ID.

Status of This Memo

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Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Overhead of Security Protocols  . . . . . . . . . . . . . . .   3
     2.1.  DTLS 1.2  . . . . . . . . . . . . . . . . . . . . . . . .   3
       2.1.1.  DTLS 1.2  . . . . . . . . . . . . . . . . . . . . . .   3
       2.1.2.  DTLS 1.2 with 6LoWPAN-GHC . . . . . . . . . . . . . .   4
       2.1.3.  DTLS 1.2 with Connection ID . . . . . . . . . . . . .   4
       2.1.4.  DTLS 1.2 with Connection ID and 6LoWPAN-GHC . . . . .   5
     2.2.  DTLS 1.3  . . . . . . . . . . . . . . . . . . . . . . . .   6
       2.2.1.  DTLS 1.3  . . . . . . . . . . . . . . . . . . . . . .   6
       2.2.2.  DTLS 1.3 with 6LoWPAN-GHC . . . . . . . . . . . . . .   6
       2.2.3.  DTLS 1.3 with Connection ID . . . . . . . . . . . . .   7
       2.2.4.  DTLS 1.3 with Connection ID and 6LoWPAN-GHC . . . . .   7
       2.2.5.  DTLS 1.3 with short header  . . . . . . . . . . . . .   8
       2.2.6.  DTLS 1.3 with short header and 6LoWPAN-GHC  . . . . .   8
     2.3.  TLS 1.2 . . . . . . . . . . . . . . . . . . . . . . . . .   9
       2.3.1.  TLS 1.2 . . . . . . . . . . . . . . . . . . . . . . .   9
       2.3.2.  TLS 1.2 with 6LoWPAN-GHC  . . . . . . . . . . . . . .   9
     2.4.  TLS 1.3 . . . . . . . . . . . . . . . . . . . . . . . . .  10
       2.4.1.  TLS 1.3 . . . . . . . . . . . . . . . . . . . . . . .  10
       2.4.2.  TLS 1.3 with 6LoWPAN-GHC  . . . . . . . . . . . . . .  10
     2.5.  OSCORE  . . . . . . . . . . . . . . . . . . . . . . . . .  11
   3.  Overhead with Different Parameters  . . . . . . . . . . . . .  12
   4.  Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .  14
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   7.  Informative References  . . . . . . . . . . . . . . . . . . .  15
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   This document analyzes and compares per-packet message size overheads
   when using different security protocols to secure CoAP over UPD
   [RFC7252] and TCP [RFC8323].  The analyzed security protocols are
   DTLS 1.2 [RFC6347], DTLS 1.3 [I-D.ietf-tls-dtls13], TLS 1.2
   [RFC5246], TLS 1.3 [I-D.ietf-tls-tls13], and OSCORE
   [I-D.ietf-core-object-security].  The DTLS and TLS record layers are
   analyzed with and without compression.  DTLS is anlyzed with and
   without Connection ID [I-D.ietf-tls-dtls-connection-id] and DTLS 1.3
   is analyzed with and without the use of the short header.  Readers
   are expected to be familiar with some of the terms described in RFC
   7925 [RFC7925], such as ICV.







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2.  Overhead of Security Protocols

   To enable comparison, all the overhead calculations in this section
   use AES-CCM with a tag length of 8 bytes (i.e.  AES_128_CCM_8, AES-
   CCM-16-64, or AES-CCM-64-64), a plaintext of 6 bytes, and the
   sequence number '05'.  This follows the example in [RFC7400],
   Figure 16.

   Note that the compressed overhead calculations for DLTS 1.2, DTLS
   1.3, TLS 1.2 and TLS 1.3 are dependent on the parameters epoch,
   sequence number, and length, and all the overhead calculations are
   dependent on the parameter Connection ID when used.  Note that the
   OSCORE overhead calculations are dependent on the CoAP option
   numbers, as well as the length of the OSCORE parameters Sender ID and
   Sequence Number.  The following are only examples.

2.1.  DTLS 1.2

2.1.1.  DTLS 1.2

   This section analyzes the overhead of DTLS 1.2 [RFC6347].  The nonce
   follow the strict profiling given in [RFC7925].  This example is
   taken directly from [RFC7400], Figure 16.

   DTLS 1.2 Record Layer (35 bytes, 29 bytes overhead):
   17 fe fd 00 01 00 00 00 00 00 05 00 16 00 01 00
   00 00 00 00 05 ae a0 15 56 67 92 4d ff 8a 24 e4
   cb 35 b9

   Content type:
   17
   Version:
   fe fd
   Epoch:
   00 01
   Sequence number:
   00 00 00 00 00 05
   Length:
   00 16
   Nonce:
   00 01 00 00 00 00 00 05
   Ciphertext:
   ae a0 15 56 67 92
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   DTLS 1.2 gives 29 bytes overhead.




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2.1.2.  DTLS 1.2 with 6LoWPAN-GHC

   This section analyzes the overhead of DTLS 1.2 [RFC6347] when
   compressed with [RFC7400].  The compression was done with
   [OlegHahm-ghc].

   Note that the sequence number '01' used in [RFC7400], Figure 15 gives
   an exceptionally small overhead that is not representative.

   Note that this header compression is not available when DTLS is
   exchanged over transports that do not use 6LoWPAN together with
   6LoWPAN-GHC.

   Compressed DTLS 1.2 Record Layer (22 bytes, 16 bytes overhead):
   b0 c3 03 05 00 16 f2 0e ae a0 15 56 67 92 4d ff
   8a 24 e4 cb 35 b9

   Compressed DTLS 1.2 Record Layer Header and Nonce:
   b0 c3 03 05 00 16 f2 0e
   Ciphertext:
   ae a0 15 56 67 92
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   When compressed with 6LoWPAN-GHC, DTLS 1.2 with the above parameters
   (epoch, sequence number, length) gives 16 bytes overhead.

2.1.3.  DTLS 1.2 with Connection ID

   This section analyzes the overhead of DTLS 1.2 [RFC6347] with
   Connection ID [I-D.ietf-tls-dtls-connection-id].  The overhead
   calculations in this section uses Connection ID = '42'.  DTLS with a
   Connection ID = '' (the empty string) is equal to DTLS without
   Connection ID.

















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   DTLS 1.2 Record Layer (36 bytes, 30 bytes overhead):
   17 fe fd 00 01 00 00 00 00 00 05 42 00 16 00 01
   00 00 00 00 00 05 ae a0 15 56 67 92 4d ff 8a 24
   e4 cb 35 b9

   Content type:
   17
   Version:
   fe fd
   Epoch:
   00 01
   Sequence number:
   00 00 00 00 00 05
   Connection ID:
   42
   Length:
   00 16
   Nonce:
   00 01 00 00 00 00 00 05
   Ciphertext:
   ae a0 15 56 67 92
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   DTLS 1.2 with Connection ID gives 30 bytes overhead.

2.1.4.  DTLS 1.2 with Connection ID and 6LoWPAN-GHC

   This section analyzes the overhead of DTLS 1.2 [RFC6347] with
   Connection ID [I-D.ietf-tls-dtls-connection-id] when compressed with
   [RFC7400] [OlegHahm-ghc].

   Note that the sequence number '01' used in [RFC7400], Figure 15 gives
   an exceptionally small overhead that is not representative.

   Note that this header compression is not available when DTLS is
   exchanged over transports that do not use 6LoWPAN together with
   6LoWPAN-GHC.













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   Compressed DTLS 1.2 Record Layer (23 bytes, 17 bytes overhead):
   b0 c3 04 05 42 00 16 f2 0e ae a0 15 56 67 92 4d
   ff 8a 24 e4 cb 35 b9

   Compressed DTLS 1.2 Record Layer Header and Nonce:
   b0 c3 04 05 42 00 16 f2 0e
   Ciphertext:
   ae a0 15 56 67 92
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   When compressed with 6LoWPAN-GHC, DTLS 1.2 with the above parameters
   (epoch, sequence number, Connection ID, length) gives 17 bytes
   overhead.

2.2.  DTLS 1.3

2.2.1.  DTLS 1.3

   This section analyzes the overhead of DTLS 1.3 [I-D.ietf-tls-dtls13].
   The changes compared to DTLS 1.2 are: omission of version number,
   merging of epoch and sequence number fields (of total 8 bytes) into
   one 4-bytes-field.

   DTLS 1.3 Record Layer (22 bytes, 16 bytes overhead):
   17 40 00 00 05 00 0f ae a0 15 56 67 92 ec 4d ff
   8a 24 e4 cb 35 b9

   Content type:
   17
   Epoch and Sequence:
   40 00 00 05
   Length:
   00 0f
   Ciphertext (including encrypted ContentType):
   ae a0 15 56 67 92 ec
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   DTLS 1.3 gives 16 bytes overhead.

2.2.2.  DTLS 1.3 with 6LoWPAN-GHC

   This section analyzes the overhead of DTLS 1.3 [I-D.ietf-tls-dtls13]
   when compressed with [RFC7400] [OlegHahm-ghc].






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   Note that this header compression is not available when DTLS is
   exchanged over transports that do not use 6LoWPAN together with
   6LoWPAN-GHC.

   Compressed DTLS 1.3 Record Layer (23 bytes, 17 bytes overhead):
   02 17 40 80 12 05 00 0f ae a0 15 56 67 92 ec 4d
   ff 8a 24 e4 cb 35 b9

   Compressed DTLS 1.3 Record Layer Header and Nonce:
   02 17 40 80 12 05 00 0f
   Ciphertext (including encrypted ContentType):
   ae a0 15 56 67 92 ec
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   When compressed with 6LoWPAN-GHC, DTLS 1.3 with the above parameters
   (epoch, sequence number, length) gives 17 bytes overhead.

2.2.3.  DTLS 1.3 with Connection ID

   This section analyzes the overhead of DTLS 1.3 [I-D.ietf-tls-dtls13]
   with Connection ID [I-D.ietf-tls-dtls-connection-id].

   DTLS 1.3 Record Layer (23 bytes, 17 bytes overhead):
   17 40 00 00 05 42 00 0f ae a0 15 56 67 92 ec 4d
   ff 8a 24 e4 cb 35 b9

   Content type:
   17
   Epoch and Sequence:
   40 00 00 05
   Connection ID:
   42
   Length:
   00 0f
   Ciphertext (including encrypted ContentType):
   ae a0 15 56 67 92 ec
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   DTLS 1.3 gives 17 bytes overhead.

2.2.4.  DTLS 1.3 with Connection ID and 6LoWPAN-GHC

   This section analyzes the overhead of DTLS 1.3 [I-D.ietf-tls-dtls13]
   with Connection ID [I-D.ietf-tls-dtls-connection-id] when compressed
   with [RFC7400] [OlegHahm-ghc].




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   Note that this header compression is not available when DTLS is
   exchanged over transports that do not use 6LoWPAN together with
   6LoWPAN-GHC.

   Compressed DTLS 1.3 Record Layer (24 bytes, 18 bytes overhead):
   02 17 40 80 13 05 42 00 0f ae a0 15 56 67 92 ec
   4d ff 8a 24 e4 cb 35 b9

   Compressed DTLS 1.3 Record Layer Header and Nonce:
   02 17 40 80 13 05 42 00 0f
   Ciphertext (including encrypted ContentType):
   ae a0 15 56 67 92 ec
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   When compressed with 6LoWPAN-GHC, DTLS 1.3 with the above parameters
   (epoch, sequence number, Connection ID, length) gives 18 bytes
   overhead.

2.2.5.  DTLS 1.3 with short header

   This section analyzes the overhead of DTLS 1.3 with short header
   format [I-D.ietf-tls-dtls13].  The short header format for DTLS 1.3
   reduces the header of 5 bytes, by omitting the length value and
   sending 1 lower bit of epoch value instead of 2, and 12 lower bits of
   sequence number instead of 30.

   DTLS 1.3 Record Layer (17 bytes, 11 bytes overhead):
   30 05 ae a0 15 56 67 92 ec 4d ff 8a 24 e4 cb 35
   b9

   DTLS 1.3 short header:
   30 05
   Ciphertext (including encrypted ContentType):
   ae a0 15 56 67 92 ec
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   DTLS 1.3 with short header gives 11 bytes overhead.

2.2.6.  DTLS 1.3 with short header and 6LoWPAN-GHC

   This section analyzes the overhead of DTLS 1.3 with short header
   [I-D.ietf-tls-dtls13] when compressed with [RFC7400] [OlegHahm-ghc].







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   Compressed DTLS 1.3 Record Layer (18 bytes, 12 bytes overhead)
   11 30 05 ae a0 15 56 67 92 ec 4d ff 8a 24 e4 cb
   35 b9

   Compressed DTLS 1.3 short header (including sequence number)
   11 30 05
   Ciphertext (including encrypted ContentType):
   ae a0 15 56 67 92 ec
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   Compressed DTLS 1.3 with short header gives 12 bytes overhead.

2.3.  TLS 1.2

2.3.1.  TLS 1.2

   This section analyzes the overhead of TLS 1.2 [RFC5246].  The changes
   compared to DTLS 1.2 is that the TLS 1.2 record layer does not have
   epoch and sequence number, and that the version is different.

   TLS 1.2 Record Layer (27 bytes, 21 bytes overhead):
   17 03 03 00 16 00 00 00 00 00 00 00 05 ae a0 15
   56 67 92 4d ff 8a 24 e4 cb 35 b9

   Content type:
   17
   Version:
   03 03
   Length:
   00 16
   Nonce:
   00 00 00 00 00 00 00 05
   Ciphertext:
   ae a0 15 56 67 92
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   TLS 1.2 gives 21 bytes overhead.

2.3.2.  TLS 1.2 with 6LoWPAN-GHC

   This section analyzes the overhead of TLS 1.2 [RFC5246] when
   compressed with [RFC7400] [OlegHahm-ghc].

   Note that this header compression is not available when TLS is
   exchanged over transports that do not use 6LoWPAN together with
   6LoWPAN-GHC.



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   Compressed TLS 1.2 Record Layer (23 bytes, 17 bytes overhead):
   05 17 03 03 00 16 85 0f 05 ae a0 15 56 67 92 4d
   ff 8a 24 e4 cb 35 b9

   Compressed TLS 1.2 Record Layer Header and Nonce:
   05 17 03 03 00 16 85 0f 05
   Ciphertext:
   ae a0 15 56 67 92
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   When compressed with 6LoWPAN-GHC, TLS 1.2 with the above parameters
   (epoch, sequence number, length) gives 17 bytes overhead.

2.4.  TLS 1.3

2.4.1.  TLS 1.3

   This section analyzes the overhead of TLS 1.3 [I-D.ietf-tls-tls13].
   The change compared to TLS 1.2 is that the TLS 1.3 record layer uses
   a different version.

   TLS 1.3 Record Layer (20 bytes, 14 bytes overhead):
   17 03 03 00 16 ae a0 15 56 67 92 ec 4d ff 8a 24
   e4 cb 35 b9

   Content type:
   17
   Legacy Version:
   03 03
   Length:
   00 0f
   Ciphertext (including encrypted ContentType):
   ae a0 15 56 67 92 ec
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   TLS 1.3 gives 14 bytes overhead.

2.4.2.  TLS 1.3 with 6LoWPAN-GHC

   This section analyzes the overhead of TLS 1.3 [I-D.ietf-tls-tls13]
   when compressed with [RFC7400] [OlegHahm-ghc].

   Note that this header compression is not available when TLS is
   exchanged over transports that do not use 6LoWPAN together with
   6LoWPAN-GHC.




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   Compressed TLS 1.3 Record Layer (21 bytes, 15 bytes overhead)
   14 17 03 03 00 0f ae a0 15 56 67 92 ec 4d ff 8a
   24 e4 cb 35 b9

   Compressed TLS 1.3 Record Layer Header and Nonce:
   14 17 03 03 00 0f
   Ciphertext (including encrypted ContentType):
   ae a0 15 56 67 92 ec
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   When compressed with 6LoWPAN-GHC, TLS 1.3 with the above parameters
   (epoch, sequence number, length) gives 15 bytes overhead.

2.5.  OSCORE

   This section analyzes the overhead of OSCORE
   [I-D.ietf-core-object-security].

   Note that Sender ID = '' (empty string) can only be used by one
   client per server.

   The examples below assume that the original messages does not have
   payload (note that this does not affect the overhead).

   The below calculation Option Delta = '9', Sender ID = '' (empty
   string), and Sequence Number = '05', and is only an example.

   OSCORE Request (19 bytes, 13 bytes overhead):
   92 09 05
   ff ec ae a0 15 56 67 92 4d ff 8a 24 e4 cb 35 b9

   CoAP Option Delta and Length
   92
   Option Value (flag byte and sequence number):
   09 05
   Payload Marker
   ff
   Ciphertext (including encrypted code):
   ec ae a0 15 56 67 92
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   The below calculation Option Delta = '9', Sender ID = '42', and
   Sequence Number = '05', and is only an example.






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   OSCORE Request (20 bytes, 14 bytes overhead):
   93 09 05 42
   ff ec ae a0 15 56 67 92 4d ff 8a 24 e4 cb 35 b9

   CoAP Option Delta and Length
   93
   Option Value (flag byte, sequence number, and Sender ID):
   09 05 42
   Payload Marker
   ff
   Ciphertext (including encrypted code):
   ec ae a0 15 56 67 92
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   The below calculation uses Option Delta = '9'.

   OSCORE Response (17 bytes, 11 bytes overhead):
   90
   ff ec ae a0 15 56 67 92 4d ff 8a 24 e4 cb 35 b9

   CoAP Delta and Option Length:
   90
   Option Value
   -
   Payload Marker
   ff
   Ciphertext (including encrypted code):
   ec ae a0 15 56 67 92
   ICV:
   4d ff 8a 24 e4 cb 35 b9

   OSCORE with the above parameters gives 13-14 bytes overhead for
   requests and 11 bytes overhead for responses.

   Unlike DTLS and TLS, OSCORE has much smaller overhead for responses
   than requests.

3.  Overhead with Different Parameters

   The DTLS overhead is dependent on the parameter Connection ID.  The
   following overheads apply for all Connection IDs with the same
   length.

   The compression overhead (GHC) is dependent on the parameters epoch,
   sequence number, Connection ID, and length (where applicable).  The
   following overheads should be representative for sequence numbers and
   Connection IDs with the same length.



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   The OSCORE overhead is dependent on the included CoAP Option numbers
   as well as the length of the OSCORE parameters Sender ID and sequence
   number.  The following overheads apply for all sequence numbers and
   Sender IDs with the same length.

       Sequence Number                '05'       '1005'     '100005'
       -------------------------------------------------------------
       DTLS 1.2                        29          29          29
       DTLS 1.3                        16          16          16
       DTLS 1.3 (short header)         11          11          11
       -------------------------------------------------------------
       DTLS 1.2 (GHC)                  16          16          16
       DTLS 1.3 (GHC)                  17          17          17
       DTLS 1.3 (short header) (GCH)   12          12          12
       -------------------------------------------------------------
       TLS  1.2                        21          21          21
       TLS  1.3                        14          14          14
       -------------------------------------------------------------
       TLS  1.2 (GHC)                  17          18          19
       TLS  1.3 (GHC)                  15          16          17
       -------------------------------------------------------------
       OSCORE Request                  13          14          15
       OSCORE Response                 11          11          11

       Figure 1: Overhead in bytes as a function of sequence number
                        (Connection/Sender ID = '')

       Connection/Sender ID            ''         '42'       '4002'
       -------------------------------------------------------------
       DTLS 1.2                        29          30          31
       DTLS 1.3                        16          17          18
       DTLS 1.3 (short header)         11          12          13
       -------------------------------------------------------------
       DTLS 1.2 (GHC)                  16          17          18
       DTLS 1.3 (GHC)                  17          18          19
       DTLS 1.3 (short header) (GCH)   12          13          14
       -------------------------------------------------------------
       OSCORE Request                  13          14          15
       OSCORE Response                 11          11          11

     Figure 2: Overhead in bytes as a function of Connection/Sender ID
                            (Sequence Number = '05')









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       Protocol                     Overhead      Overhead (GHC)
       -------------------------------------------------------------
       DTLS 1.2                        21               8
       DTLS 1.3                         8               9
       DTLS 1.3 (short header)          3               4
       -------------------------------------------------------------
       TLS  1.2                        13               9
       TLS  1.3                         6               7
       -------------------------------------------------------------
       OSCORE Request                   5
       OSCORE Response                  3

   Figure 3: Overhead (excluding ICV) in bytes       (Connection/Sender
                     ID = '', Sequence Number = '05')

4.  Summary

   DTLS 1.2 has quite a large overhead as it uses an explicit sequence
   number and an explicit nonce.  TLS 1.2 has significantly less (but
   not small) overhead.  TLS 1.3 and DTLS 1.3 have quite small overhead.
   OSCORE and DTLS 1.3 with short header format has very small overhead.

   The Generic Header Compression (6LoWPAN-GHC) can in addition to DTLS
   1.2 handle TLS 1.2, and DTLS 1.2 with Connection ID.  The Generic
   Header Compression (6LoWPAN-GHC) works very well for Connection ID
   and the overhead seems to increase exactly with the length of the
   Connection ID (which is optimal).  The compression of TLS 1.2 is not
   as good as the compression of DTLS 1.2 (as the static dictionary only
   contains the DTLS 1.2 version number).  Similar compression levels as
   for DTLS could be achieved also for TLS 1.2, but this would require
   different static dictionaries.  For TLS 1.3 and DTLS 1.3, GHC
   increases the overhead.  The 6LoWPAN-GHC header compression is not
   available when (D)TLS is exchanged over transports that do not use
   6LoWPAN together with 6LoWPAN-GHC.

   The short header format for DTLS 1.3 reduces the header of 5 bytes,
   by omitting the length value and sending 1 lower bit of epoch value
   instead of 2, and 12 lower bits of sequence number instead of 30.
   This may create problems reconstructing the full sequence number, if
   ~2000 datagrams in sequence are lost.

   OSCORE has much lower overhead than DTLS 1.2 and TLS 1.2.  The
   overhead of OSCORE is smaller than DTLS 1.2 and TLS 1.2 over 6LoWPAN
   with compression, and this small overhead is achieved even on
   deployments without 6LoWPAN or 6LoWPAN without DTLS compression.
   OSCORE is lightweight because it makes use of some excellent features
   in CoAP, CBOR, and COSE.




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5.  Security Considerations

   This document is purely informational.

6.  IANA Considerations

   This document has no actions for IANA.

7.  Informative References

   [I-D.ietf-core-object-security]
              Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
              "Object Security for Constrained RESTful Environments
              (OSCORE)", draft-ietf-core-object-security-11 (work in
              progress), March 2018.

   [I-D.ietf-tls-dtls-connection-id]
              Rescorla, E., Tschofenig, H., Fossati, T., and T. Gondrom,
              "The Datagram Transport Layer Security (DTLS) Connection
              Identifier", draft-ietf-tls-dtls-connection-id-00 (work in
              progress), December 2017.

   [I-D.ietf-tls-dtls13]
              Rescorla, E., Tschofenig, H., and N. Modadugu, "The
              Datagram Transport Layer Security (DTLS) Protocol Version
              1.3", draft-ietf-tls-dtls13-26 (work in progress), March
              2018.

   [I-D.ietf-tls-tls13]
              Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", draft-ietf-tls-tls13-27 (work in progress),
              March 2018.

   [OlegHahm-ghc]
              Hahm, O., "Generic Header Compression", July 2016,
              <https://github.com/OlegHahm/ghc>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <https://www.rfc-editor.org/info/rfc5246>.

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
              January 2012, <https://www.rfc-editor.org/info/rfc6347>.






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   [RFC7252]  Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
              Application Protocol (CoAP)", RFC 7252,
              DOI 10.17487/RFC7252, June 2014,
              <https://www.rfc-editor.org/info/rfc7252>.

   [RFC7400]  Bormann, C., "6LoWPAN-GHC: Generic Header Compression for
              IPv6 over Low-Power Wireless Personal Area Networks
              (6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November
              2014, <https://www.rfc-editor.org/info/rfc7400>.

   [RFC7925]  Tschofenig, H., Ed. and T. Fossati, "Transport Layer
              Security (TLS) / Datagram Transport Layer Security (DTLS)
              Profiles for the Internet of Things", RFC 7925,
              DOI 10.17487/RFC7925, July 2016,
              <https://www.rfc-editor.org/info/rfc7925>.

   [RFC8323]  Bormann, C., Lemay, S., Tschofenig, H., Hartke, K.,
              Silverajan, B., and B. Raymor, Ed., "CoAP (Constrained
              Application Protocol) over TCP, TLS, and WebSockets",
              RFC 8323, DOI 10.17487/RFC8323, February 2018,
              <https://www.rfc-editor.org/info/rfc8323>.

Acknowledgments

   The authors want to thank Ari Keraenen, Carsten Bormann, Goeran
   Selander, and Hannes Tschofenig for comments and suggestions on
   previous versions of the draft.

   All 6LoWPAN-GHC compression was done with [OlegHahm-ghc].

Authors' Addresses

   John Mattsson
   Ericsson AB

   Email: john.mattsson@ericsson.com


   Francesca Palombini
   Ericsson AB

   Email: francesca.palombini@ericsson.com









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