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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IETF Anoop Kumar Pandey 3 Internet-Draft C-DAC Bangalore 4 Intended status: Informational January 31, 2019 5 Expires: August 4, 2019 7 AutoAdd - Automatic Bootstrapping of IoT Devices 8 draft-autoadd-auto-bootstrapping-iot-devices-00 10 Abstract 12 IoT devices are fast getting embedded into our lives, and when put 13 together they have the potential to generate a precise and detailed 14 history of our lives and store them forever. Their networking and 15 communicational power can be unleashed for malicious and sabotage 16 purposes, by a motivated attacker sitting in the far corner of the 17 world. Attacks on Industrial IoT systems can cause greater 18 disasters. It is therefore essential to inculcate the security 19 aspect, right from design to development to operations. The first 20 operation of an IoT device is to bootstrap itself, and due importance 21 should be placed to ensure that this operation is carried out 22 securely and with due diligence. However, it's easier said than 23 done, and this paper outlines several approaches for secure automated 24 bootstrapping and also proposes a new method, which is compared 25 against the existing mechanisms for several qualitative factors. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at https://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on August 4, 2019. 44 Copyright Notice 46 Copyright (c) 2019 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (https://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Prologue . . . . . . . . . . . . . . . . . . . . . . . . . . 2 62 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 63 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 64 3. Prior and Ongoing Contributions . . . . . . . . . . . . . . . 3 65 3.1. TOFU (Trust on First Use) . . . . . . . . . . . . . . . . 3 66 3.2. Resurrecting Duckling . . . . . . . . . . . . . . . . . . 4 67 3.3. Enrollment over Secure Transport . . . . . . . . . . . . 4 68 3.4. BRSKI . . . . . . . . . . . . . . . . . . . . . . . . . . 4 69 3.5. EAP-NooB . . . . . . . . . . . . . . . . . . . . . . . . 5 70 3.6. AutoAdd (Work in Progress) . . . . . . . . . . . . . . . 5 71 4. Comparison Chart . . . . . . . . . . . . . . . . . . . . . . 6 72 5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 7 73 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 74 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 75 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 76 8.1. Normative References . . . . . . . . . . . . . . . . . . 8 77 8.2. Informative References . . . . . . . . . . . . . . . . . 8 78 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8 80 1. Prologue 82 Amazon launched "Amazon Alexa" in November 2014. Alexa is a virtual 83 assistant which comes with Echo line of smart speakers. It is 84 capable of voice interaction, control of smart home devices, music 85 playback, setting alarms, making calls, checking weather and news and 86 much more. 87 Google Home series smart speakers were launched in November 2016. 88 Google Assistant can be used to control thousands of smart-home 89 products from several brands like LG, GE, Whirlpool, Nest etc... 90 Google Home can be asked to change the temperature, dim the lights, 91 turn on a microwave or kettle, and also start Roomba (robotic vacuum 92 cleaners). It can also turn the TV on/off using Chromecast. 93 The concept of smart home and devices is taking off very fast. It 94 appears to make our lives quite easy and comfortable. But turning 95 your home into a computer means facing computer-like problems. The 96 security and performance issues associated are much scary. 98 It creates a method for transformation of the physical world into 99 computer-based systems, resulting in performance and efficiency 100 enhancement, financial gains, and reduces human involvement. The 101 number of IoT devices increased 31% year-over-year to 8.4 billion in 102 2017 and it is estimated to have 30 billion IoT devices by 2020 103 [iotscale]. Many more devices are/will be connected through serial 104 link. 106 2. Introduction 108 Kevin Ashton coined the term "Internet of Things (IoT)" and defined 109 it as a system where the internet is connected to the physical world 110 via ubiquitous sensors. While, the scale of IoT is going pretty 111 bigger day by day, the task of adding new devices and bootstrapping 112 it at such a large scale, remains at large. Manual bootstrapping 113 requires a human to add an IoT device to a network (network 114 discovery), connect to registrar (system where a device can be 115 registered), setting up the key for future secure communication and 116 finally all configuration of the device for its functioning in the 117 network domain. Automatic bootstrapping methods are still evolving 118 and are under testing and scrutiny for various environments and 119 scenarios. While security experts and engineers are toiling hard to 120 mitigate risks associated with automatic bootstrapping, we propose a 121 system AutoAdd (work in progress), which ensures automatic addition 122 and initial bootstrapping of an IoT device while it is put on the 123 network. There are billions of devices and at least thousands of 124 manufacturers. So how do we identify and trust a device? Similarly 125 there are many networks, how does the device know that I am working 126 only with my owner and not with some imposter network? Remember, 127 there are hostile devices on the network, and there are hostile 128 networks that might attempt to take over the device. Basically, we 129 need to establish the identity/authenticity of the device; Check if 130 device is compromised or not; establish the identity of the network/ 131 domain; and finally check if the domain is the correct one. 133 2.1. Requirements Language 135 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 136 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 137 document are to be interpreted as described in RFC 2119 [RFC2119]. 139 3. Prior and Ongoing Contributions 141 3.1. TOFU (Trust on First Use) 143 TOFU (Trust on First Use) calls for accepting and storing a public 144 key or credential associated with an asserted identity, without 145 authenticating that assertion. Subsequent communication that is 146 authenticated using the cached key or credential is secure against an 147 MiTM attack, if such an attack did not succeed during the vulnerable 148 initial communication. 150 3.2. Resurrecting Duckling 152 In 'Resurrecting Duckling' [stajano1999resurrecting], a device 153 recognises as its owner the first entity that sends it a secret key 154 and will stay loyal to its owner for the rest of the life. It may 155 come to EoL (end of life), or may be reset. The ownership of the 156 device may also be transferred. It is analogous to imprinting in 157 ducks, where duckling emerging from its egg will recognise as its 158 mother the first moving object it sees that makes a sound, regardless 159 of what it looks like. 161 3.3. Enrollment over Secure Transport 163 In Enrollment over Secure Transport (EST) RFC 7030 [RFC7030], the 164 client starts a TLS based HTTPS session with an EST server. Through 165 a part of URI, a specific EST service is requested during the 166 session. The client authenticates the server and the server 167 authenticates the client. The server verifies if the client is 168 authorized to use the requested service. Similarly the client 169 verifies if the server has proper authorization to serve this client. 170 Upon complete authentication and authorization check of both the 171 parties, the server responds to the client request. 173 3.4. BRSKI 175 An ongoing internet draft BRSKI (Bootstrapping Remote Secure Key 176 Infrastructures) [I-D.ietf-anima-bootstrapping-keyinfra] lists steps 177 for auto bootstrapping as follow: 179 o Pledge discovers a communication channel to a Registrar. 181 o Pledge identifies itself. This is done by presenting an X.509 182 IDevID credential to the discovered Registrar (via the Proxy) in a 183 TLS handshake. (The Registrar credentials are only provisionally 184 accepted at this time) 186 o Pledge requests to join the discovered Registrar using a voucher 187 request. 189 o Registrar sends the voucher request to the MASA (manufacturer). 190 URL of MASA can be in the voucher request or embedded in 191 Registrar. 193 o MASA sends the voucher which is passed to pledge. 195 o MASA sends the voucher which is passed to pledge. 197 o Pledge verifies the voucher and imprints to the registrar by send 198 voucher status telemetry. 200 o Registrar verifies the voucher and enrolls the pledge to the 201 domain 203 Here pledge is the device to be added to network/domain; registrar is 204 the registration authority where devices are registered; MASA is 205 manufacturer authorized signing authority; IDevID is an Initial 206 Device Identity X.509 certificate installed by the vendor on new 207 equipment and voucher is a signed statement from the MASA service 208 that indicates to a Pledge the cryptographic identity of the 209 Registrar it should trust. 211 3.5. EAP-NooB 213 EAP-NooB (Extensible Authentication Protocol Nimble out of Band) 214 [I-D.aura-eap-noob] method is intended for bootstrapping all kinds of 215 Internet-of-Things (IoT) devices that have a minimal user interface 216 and no pre-configured authentication credentials. The method makes 217 use of a user-assisted one-directional OOB (out of band) channel 218 between the peer device and authentication server. The secure 219 bootstrapping in this specification makes use of a user-assisted out- 220 of-band (OOB) channel. The security is based on the assumption that 221 attackers are not able to observe or modify the messages conveyed 222 through the OOB channel. EAP-NooB follows the common approach of 223 performing a Diffie-Hellman key exchange over the insecure network 224 and authenticating the established key with the help of the OOB 225 channel in order to prevent impersonation and man-in-the-middle 226 (MitM) attacks. 228 3.6. AutoAdd (Work in Progress) 230 We propose AutoAdd: an automatic bootstrapping method for IoT 231 devices. This is a work in progress and open for comments. 232 When a device is purchased in real world, usually an invoice is 233 issued in the name of the purchaser with stamp of vendor/ 234 manufacturer. We propose that similarly, a digital invoice can be 235 issued which will contain the public key(s) of the and digitally signed by the manufacturer. The 237 digital invoice may be embedded in the device along with the IDevID. 238 A digital invoice may be contain the IDevID of the device and Public 239 key of Registrars (Ri), digital signed by Manufacturer (M) and can be 240 represented as below. 242 Dig_Invoice = DigSignM {IDevID, PubKey: [R1, R2, .., Rn]} 243 When the device starts the registration process, it will present the 244 digital invoice along with IDevID. The Registrar can verify the 245 digital signature of the manufacturer on the digital invoice and sent 246 a signed note of acceptance to the device. 248 Flag = VerifyDigSignManufacturer (Dig_Invoice, PubKeyM) 249 if (flag) Acceptance_Note = DigSignRi {Note} 251 The device can verify the signed note using the public key(s) 252 mentioned in the digital invoice, thereby verifying its true owner. 254 VerifyDigSignRegistrar (Acceptance_Note, PublicKeyFromDigInvoiceRi) 256 This process with eliminate all the communication overhead with MASA 257 and multiple level verification (voucher request, voucher, telemetry 258 etc. at Registrar/ MASA/Device. From security point of view, we can 259 claim that given that the digital invoice is digitally signed by 260 manufacturer, the public key of domain owner embedded in the digital 261 invoice can't be changed, otherwise verification of digital signature 262 of manufacturer at Registrar end will fail. 264 4. Comparison Chart 265 +--------------+-------------------------+--------------------------+ 266 | Approach | Security | Constraints/Consequence | 267 +--------------+-------------------------+--------------------------+ 268 | TOFU | Vulnerable initial | No authentication of | 269 | | communication | initial assertion | 270 +--------------+-------------------------+--------------------------+ 271 | Resurrecting | No owner authentication | Anyone can be the owner | 272 | Duckling | | | 273 +--------------+-------------------------+--------------------------+ 274 | EST | TLS secured HTTP | | 275 | | session between client | | 276 | | and Server | | 277 +--------------+-------------------------+--------------------------+ 278 | BRSKI | Online service | MASA should be always | 279 | | authenticating both | online; No auto run of | 280 | | device and domain | BRSKI on network or | 281 | | | ownership change | 282 +--------------+-------------------------+--------------------------+ 283 | EAP-NooB | Security dependent on | Manual intervention for | 284 | | Ephemeral Elliptic | OOB authentication; Not | 285 | | Curve Diffie-Hellman | Scalable | 286 | | (ECDHE) key exchange | | 287 | | and manual assistance | | 288 +--------------+-------------------------+--------------------------+ 289 | AutoAdd | Easy offline | | 290 | | authentication of both | | 291 | | device and domain | | 292 +--------------+-------------------------+--------------------------+ 294 Table 1: Comparison of various bootstrapping methods 296 5. Conclusion 298 AutoAdd can serve as a secure automatic bootstrapping method for IoT 299 devices. The testing of the same is undergoing. Details will follow 300 soon in upcoming version. We are also working on a internet draft to 301 incorporate device certificates with EAP-NOOB. 303 6. IANA Considerations 305 This memo includes no request to IANA. 307 7. Security Considerations 309 This draft proposes an automatic bootstrapping method for IoT 310 devices. The security of the protocol is inherent from the security 311 of unforgeable digital signature and PKI. A detailed security 312 analysis is pending. 314 8. References 316 8.1. Normative References 318 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 319 Requirement Levels", BCP 14, RFC 2119, 320 DOI 10.17487/RFC2119, March 1997, 321 . 323 [RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed., 324 "Enrollment over Secure Transport", RFC 7030, 325 DOI 10.17487/RFC7030, October 2013, 326 . 328 8.2. Informative References 330 [I-D.aura-eap-noob] 331 Aura, T. and M. Sethi, "Nimble out-of-band authentication 332 for EAP (EAP-NOOB)", draft-aura-eap-noob-04 (work in 333 progress), October 2018. 335 [I-D.ietf-anima-bootstrapping-keyinfra] 336 Pritikin, M., Richardson, M., Behringer, M., Bjarnason, 337 S., and K. Watsen, "Bootstrapping Remote Secure Key 338 Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping- 339 keyinfra-18 (work in progress), January 2019. 341 [iotscale] 342 Nordrum, Amy., "Popular Internet of Things Forecast of 50 343 Billion Devices by 2020 Is Outdated", 2016, 344 . 348 [stajano1999resurrecting] 349 Frank, Stajano., "The resurrecting duckling", 1999, 350 . 353 Author's Address 355 Anoop Kumar Pandey 356 C-DAC Bangalore 357 #68, Electronics City 358 Bangalore 560100 359 India 361 Email: anoop@cdac.in