Internet DRAFT - draft-urien-core-tls-se-io
draft-urien-core-tls-se-io
CORE Working Group P. Urien
Internet Draft Telecom Paris
Intended status: Experimental
February 25 2024
Expires: August 2024
TLS for Secure Element Input Output (TLS-SE-IO)
draft-urien-core-tls-se-io-02.txt
Abstract
The goal of TLS-SE-IO is to provide virtual IO pins for secure
elements running TLS servers, in order to interact with sensors and
actuators. TLS-SE device processes TLS packets in secure element. It
may work like a black box (server mode) that exchanges fully
encrypted packets. It may also export encrypted packet in clear
form, in order to provide virtual output pin. Output messages may
include cookies and/or cryptographic materials. Virtual input pin
forwards input messages, triggered by previous output messages, and
sent to TLS-SE device for further processing.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 2024.
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Copyright Notice
Copyright (c) 2024 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
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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warranty as described in the Simplified BSD License.
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TLS-SE-IO February 2024
Table of Contents
Abstract........................................................... 1
Requirements Language.............................................. 1
Status of this Memo................................................ 1
Copyright Notice................................................... 2
1 Overview......................................................... 4
2 TLS-SE-IO........................................................ 4
3 TLS-SE-IO Protocol............................................... 5
3.1 Output messages............................................. 5
3.2 Input message............................................... 6
4 Example.......................................................... 6
5 Security Considerations.......................................... 8
6 IANA Considerations.............................................. 8
7 References....................................................... 8
7.1 Normative References........................................ 8
7.2 Informative References...................................... 9
8 Authors' Addresses............................................... 9
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1 Overview
Input output (IO) interfaces are used in the internet of things
context (IoT) to manage sensors and actuators.
Output pin has two binary states, one or zero, and can generate a
bit stream, i.e. messages comprising a set of bytes.
Input pin detects two binary states, one or zero, which can realize
a bit stream, i.e. messages comprising a set of bytes.
Usually input messages are triggered by previous output messages.
Secure elements, mainly specified by [ISO7816] standards have
multiple form factors, such as SIM card, or surface mounted device
(SMD). They provide tamper resistant computing resources. According
to Common Criteria (CC) standards, their Evaluation Assurance Level
ranges between EAL4 to EAL6+, EAL7 being the highest level.
Nevertheless secure elements have no IO pins, and are not able to
physically communicate with sensors and actuators. However they may
be connected to processors, with physical IO capacities (i.e.
equipped with IO pins)
This document describes the processing of output and input messages
by secure elements that execute TLS server. Output messages are
exported from the secure element in clear form; they provide an
output byte stream. Input messages are triggered by output messages;
a byte stream is forwarded to secure element for further processing.
2 TLS-SE-IO
The draft [TLS-SE] defines [TLS 1.3] support for secure elements.
Two procedures RECV and SEND realize a logical bridge between TLS
packets and [ISO7816] messages.
+-----------+ recv +------------+ RECV +-----------+
| IP + ---> | TCP/IP | ---> | TLS 1.3 |
| Network +------+ Constraint +------+ Secure |
| | <--- | Node | <--- | Element |
+-----------+ send +------------+ SEND +-----------+
| |
Network Interface ISO7816 interface
A processor physically connected to secure element (the secure
element processor, SEP) can read TLS packets transparently
transported by ISO7816 requests and responses. It also knows if the
secure channel is opened, thanks to a dedicated ISO7816 status word
(sw-open = 0x9001)
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+------------+ TLS-Packet +-----------+
| | ---------> | TLS 1.3 |
| Processor +------------+ Secure |
| (SEP) | <--------_ | Element |
+------------+ TLS-Packet +-----------+
SE Processor Secure Element
TLS-SE provides two classes of service:
- TLS-SE as server, this is the technological basis for [IOSE]
framework. The secure element is a black box providing secure
storage and tamper resistant computing resources.
- TLS-SE as stack. The secure element fully processes TLS session
opening, i.e. TLS flights. It provides TLS packets encryption (TLS-
Encrypt) and decryption (TLS-Decrypt) procedures.
+------------+ +------------+
| +-<----- Output ----<-+-+ |
| | | |Decryption|
| +-- Rx-TLS-Packets ->-+-+ |
| SEP | | TLS-SE |
| +-<- Tx-TLS-Packets <-+-+ |
| | | |Encryption|
| +->------Input ----->-+-+ |
+------------+ +------------+
The main idea of TLS-SE-IO is to provide virtual Input/Output (IO)
resources (i.e. virtual IO pins) to TLS-SE secure element.
- Output requests MUST be received in encrypted TLS record messages.
Clear messages are returned by secure element.
- Input messages are triggered by output requests. They MUST be
encrypted by the secure element thanks to the SEND procedure
described in [TLS-SE]
3 TLS-SE-IO Protocol
The SEP entity can read incoming and outgoing TLS packets.
A TLS record packet has a five bytes header in clear form, which
comprises 3 fields, type (one byte), version (2 bytes), and length
(2 bytes)
3.1 Output messages
An output message is received in encrypted TLS record packet. It is
decrypted within TLS-SE secure element. It MUST contain an attribute
('output-mark') that triggers the output message exportation.
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The TLS-SE secure element produces a TLS packet with the first three
bytes (type and version) set to zero, and a length. The payload
comprises the data and the TLS type in clear form.
Type=0x00 Version=0x0000 Length output-message TLS-Type
An output message MAY be encrypted. It MAY also contains cookie to
be used in input messages.
Output messages are processed by SEP device. They contain any kind
of information, such as object or data serialization, script, or AT
commands for cellular serial modems.
3.2 Input message
Input message is triggered by a previous output message. It MAY be
encrypted. It MAY also contains cookie found in a previous output
message.
Input message is sent to the secure element thanks to the procedure
RECV(F-Encrypt,input-message), as specified in[TLS-SE]. It MAY
trigger a TLS record packet, according to the RECV procedure.
4 Example
PSK=
0102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F20
DHE=
45A4CB06906CD3426E9F8E02FD0EAA39E016729A8F00D08E34B907418723007E
TLS Reset
Tx: 00D8000000
Rx: 9000
RECV(F-First,ClientHello)
Tx: 00D80001F0 1603030103010000FF0303
749F4A35B3E76B4554517F221F8BD54C
C7DD96E9B70A0DBF4652821AD8AF095C
0000021304010000D4002D0003020001
002B0003020304000D001E001C060305
03040302030806080B0805080A080408
09060105010401020100330047004500
170041047ED91D5E7DC92EBF5D26444B
A267299D8D5A89481C121E7691A7D782
77668F366DEC65B6B35D707777F523C0
05B48CC7165EC151E8D9A28F22B8603B
14C11975000A00060004001800170000
000D000B0000086B6579312E636F6D00
29003A0015000F436C69656E745F6964
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656E7469747900000000002120F3793B
B581E86684
9000
RECV(F-Last,ClientHello))
Tx: 00D8000218 6F72919312AEF766B56275
B26573A433A8BD1806A492620F
Rx: 6186
SEND(ServerHello)
Tx: 00C0000086
Rx: 1603030081 0200007D03030BBDF53C07
596AACAF7724DB911E11C92F418ED96C
008451A49E7AE08230B3D10013040000
55002900020000003300450017004104
07A637DCCBF63DE1A6EFB59ADDB796FE
BC9106A96379081BC3547FB42C7982B7
A8FA04A0F7E3F1784A1A0086CBCC03BE
F8FDE7526EED3DB4F85DAF5BD26443E2
002B00020304
9F1C
SEND(ServerEncryptedExtension)
Tx: 00C000001C
Rx: 1703030017CD418DE7D2E6E8F393A5AC
B0E4E2C06BFA0B0631C59A26
9F3A
SEND(ServerFinished)
Tx: 00C000003A
Rx: 17030300350F106E7DB08E7CCB69644D
7E0F9CB39FB2B5A0AC0D36FA462A9E40
0517A548E7F9E07191ECC1F869671E3B
1F1B39D9A38E09EE6DE8
9000
RECV(F-First||F-Last, ClientFinished)
Tx: 00D800033A 1703030035C407E727ACBC
7CE96EB6A81391FF8F8546976430B8F8
65A1C8A41F279B7B4A72934A0225021B
A4001793EBFFC2167FAE250A5B69A8
Rx: 9001
TLS Secure Channel is open
Encrypted opaque message
RECV(F-First||F-Last, TLS-Record-Message)
Tx: 00D800031F170303001AE4EBF10433EB
78B4454D7ACE9EBBCB74455F232EC1A6
A6D046B5
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Rx: 611C
Encrypted opaque response
SEND(TLS-Record-Message)
Tx: 00C000001C
Rx: 1703030017215C9D0932B76BBCD439C4
5D5FEDC4C4A4253A3EC736E7
9000
Encrypted output message
RECV(F-First||F-Last, TLS-Record-Message)
Tx: 00D800031D 1703030018AEBBB88F858C
C8325E85C75FF1C95FEFA2F5D3BBD1D3
C86B
Rx: 610D
Output message in clear form (value=#tempCrLf, Type=0x17)
Character '#' is the output mark
Tx: 00C000000D
Rx: 0000000008 2374656D700D0A 17
9000
An input message is triggered by the output message
Input message in clear form
RECV(F-Encrypt||F-First||F-Last, InputMessage=18.81CrLf, Type=0x17)
Tx: 00D8020308 31382E38310D0A 17
Encrypted TLS record packet
Rx: 611D
Tx: 00C000001D
Rx: 1703030018C14E29429EA6F071D13FB8
8653C7ABE7315423E9D1A2B58B
9000
5 Security Considerations
This entire document is about security.
6 IANA Considerations
This draft does not require any action from IANA.
7 References
7.1 Normative References
[TLS 1.3] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, August 2018.
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[ISO7816] ISO 7816, "Cards Identification - Integrated Circuit Cards
with Contacts", The International Organization for Standardization
(ISO).
7.2 Informative References
[TLS-SE] IETF Draft, "Secure Element for TLS Version 1.3", draft-
urien-tls-se-07.txt, 2024
[IOSE] IETF Draft, "Internet of Secure Elements", draft-urien-
coinrg-iose-07.txt, 2023
8 Authors' Addresses
Pascal Urien
Telecom Paris
19 place Marguerite Perey
91120 Palaiseau Phone: NA
France Email: Pascal.Urien@telecom-paris.fr
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