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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 8208 (Obsoleted by RFC 8608) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group R. Bush 3 Internet-Draft IIJ Lab / Dragon Research Lab 4 Intended status: Standards Track S. Turner 5 Expires: June 21, 2019 sn3rd 6 K. Patel 7 Arrcus, Inc. 8 December 18, 2018 10 Router Keying for BGPsec 11 draft-ietf-sidrops-rtr-keying-02 13 Abstract 15 BGPsec-speaking routers are provisioned with private keys in order to 16 sign BGPsec announcements. The corresponding public keys are 17 published in the global Resource Public Key Infrastructure, enabling 18 verification of BGPsec messages. This document describes two methods 19 of generating the public-private key-pairs: router-driven and 20 operator-driven. 22 Requirements Language 24 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 25 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 26 "OPTIONAL" in this document are to be interpreted as described in BCP 27 14 [RFC2119] [RFC8174] when, and only when, they appear in all 28 capitals, as shown here. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on January 16, 2017. 47 Copyright Notice 49 Copyright (c) 2018 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 65 2. Management / Router Communication . . . . . . . . . . . . . . 3 66 3. Exchange Certificates . . . . . . . . . . . . . . . . . . . . 4 67 4. Set-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 68 5. Generate PKCS#10 . . . . . . . . . . . . . . . . . . . . . . . 4 69 5.1. Router-Generated Keys . . . . . . . . . . . . . . . . . . 5 70 5.2. Operator-Generated Keys . . . . . . . . . . . . . . . . . 5 71 5.2.1. Using PKCS#8 to Transfer Private Key . . . . . . . . . 5 72 6. Send PKCS#10 and Receive PKCS#7 . . . . . . . . . . . . . . . 6 73 7. Install Certificate . . . . . . . . . . . . . . . . . . . . . 6 74 8. Advanced Deployment Scenarios . . . . . . . . . . . . . . . . 7 75 9. Key Management . . . . . . . . . . . . . . . . . . . . . . . . 8 76 9.1. Key Validity . . . . . . . . . . . . . . . . . . . . . . . 8 77 9.2. Key Roll-Over . . . . . . . . . . . . . . . . . . . . . . 9 78 9.3. Key Revocation . . . . . . . . . . . . . . . . . . . . . . 9 79 9.4. Router Replacement . . . . . . . . . . . . . . . . . . . . 10 80 10. Security Considerations . . . . . . . . . . . . . . . . . . . 10 81 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 82 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 83 12.1. Normative References . . . . . . . . . . . . . . . . . . 12 84 12.1. Informative References . . . . . . . . . . . . . . . . . 13 85 Appendix A. Management/Router Channel Security . . . . . . . . . 14 86 Appendix B. The n00b Guide to BGPsec Key Management . . . . . . . 15 87 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 89 1. Introduction 91 BGPsec-speaking routers are provisioned with private keys, which 92 allow them to digitally sign BGPsec announcements. To verify the 93 signature, the public key, in the form of a certificate [RFC8209], is 94 published in the Resource Public Key Infrastructure (RPKI). This 95 document describes provisioning of BGPsec-speaking routers with the 96 appropriate public-private key-pairs. There are two methods, router- 97 driven and operator-driven. 99 These two methods differ in where the keys are generated: on the 100 router in the router-driven method, and elsewhere in the 101 operator-driven method. Routers are required to support at least one 102 of the methods in order to work in various deployment environments. 103 Some routers may not allow the private key to be off-loaded while 104 others may. While off-loading private keys would ease swapping of 105 routing engines, exposure of private keys is a well known security 106 risk. 108 In the operator-driven method, the operator generates the 109 private/public key-pair and sends it to the router. 111 In the router-driven method, the router generates its own 112 public/private key-pair. 114 The router-driven model mirrors the model used by traditional PKI 115 subscribers; the private key never leaves trusted storage (e.g., 116 Hardware Security Module). This is by design and supports classic 117 PKI Certification Policies for (often human) subscribers which 118 require the private key only ever be controlled by the subscriber to 119 ensure that no one can impersonate the subscriber. For non-humans, 120 this model does not always work. For example, when an operator wants 121 to support hot-swappable routers, the same private key needs to be 122 installed in the soon-to-be online router that was used by the the 123 soon-to-be offline router. This motivated the operator-driven model. 125 Sections 2 through 7 describe the various steps involved for an 126 operator to use the two methods to provision new and existing 127 routers. The methods described involve the operator configuring the 128 two end points (i.e., the management station and the router) and 129 acting as the intermediary. Section 8 describes another method that 130 requires more capable routers. 132 Useful References: [RFC8205] describes gritty details, [RFC8209] 133 specifies the format for the PKCS#10 certification request, and 134 [RFC8208] specifies the algorithms used to generate the PKCS#10's 135 signature. 137 2. Management / Router Communication 139 Operators are free to use either the router-driven or operator-driven 140 method as supported by the platform. Regardless of the method 141 chosen, operators first establish a protected channel between the 142 management system and the router. How this protected channel is 143 established is router-specific and is beyond scope of this document. 144 Though other configuration mechanisms might be used, e.g. NetConf 145 (see [RFC6470]); for simplicity, in this document, the protected 146 channel between the management platform and the router is assumed to 147 be an SSH-protected CLI. See Appendix A for security considerations 148 for this protected channel. 150 3. Exchange Certificates 152 A number of options exist for the operator management station to 153 exchange PKI-related information with routers and with the RPKI 154 including: 156 - Use application/pkcs10 media type [RFC5967] to extract certificate 157 requests and application/pkcs7-mime [I-D.lamps-rfc5751-bis] to return 158 the issued certificate, 160 - Use FTP or HTTP per [RFC2585], and 162 - Use Enrollment over Secure Transport (EST) protocol per [RFC7030]. 164 4. Set-Up 166 To start, the operator uses the protected channel to install the 167 appropriate RPKI Trust Anchor's Certificate (TA Cert) in the router. 168 This will later enable the router to validate the router certificate 169 returned in the PKCS#7 certs-only message [I-D.lamps-rfc5751-bis]. 171 The operator also configures the Autonomous System (AS) number to be 172 used in the generated router certificate. This may be the sole AS 173 configured on the router, or an operator choice if the router is 174 configured with multiple ASs. A router with multiple ASs can be 175 configured with multiple router certificates by following the process 176 of this document for each desired certificate. 178 The operator configures or extracts from the router the BGP 179 Identifier [RFC4271] to be used in the generated router certificate. 180 In the case where the operator has chosen not to use unique 181 per-router certificates, a BGP Identifier of 0 MAY be used. 183 5. Generate PKCS#10 185 The private key, and hence the PKCS#10 certification request, which 186 is sometimes referred to as a Certificate Signing Request (CSR), may 187 be generated by the router or by the operator. 189 The PKCS#10 request SHOULD be saved to enable verifying that the 190 returned public key in the certificate corresponds to the private 191 used to generate the signature on the CSR. 193 NOTE: The PKCS#10 certification request does not include the AS 194 number or the BGP Identifier for the router certificate. Therefore, 195 the operator transmits the AS it has chosen on the router and the BGP 196 Identifier as well when it sends the CSR to the CA. 198 5.1. Router-Generated Keys 200 In the router-generated method, once the protected channel is 201 established and the initial Set-Up (Section 4) performed, the 202 operator issues a command or commands for the router to generate the 203 public/private key pair, to generate the PKCS#10 certification 204 request, and to sign the PKCS#10 certification request with the 205 private key. Once generated, the PKCS#10 certification request is 206 returned to the operator over the protected channel. 208 The operator includes the chosen AS number and the BGP Identifier 209 when it sends the CSR to the CA. 211 NOTE: If a router were to communicate directly with a CA to have the 212 CA certify the PKCS#10 certification request, there would be no way 213 for the CA to authenticate the router. As the operator knows the 214 authenticity of the router, the operator mediates the communication 215 with the CA. 217 5.2. Operator-Generated Keys 219 In the operator-generated method, the operator generates the 220 public/private key pair on a management station and installs the 221 private key into the router over the protected channel. Beware that 222 experience has shown that copy and paste from a management station to 223 a router can be unreliable for long texts. 225 The operator then creates and signs the PKCS#10 certification request 226 with the private key; the operator includes the chosen AS number and 227 the BGP Identifier when it sends the CSR to the CA. 229 Even if the operator cannot extract the private key from the router, 230 this signature still provides a linkage between a private key and a 231 router. That is, the operator can verify the proof of possession 232 (POP), as required by [RFC6484]. 234 5.2.1. Using PKCS#8 to Transfer Private Key 236 A private key can be encapsulated in a PKCS#8 Asymmetric Key Package 237 [RFC5958] and should be further encapsulated in Cryptographic Message 238 Syntax (CMS) SignedData [RFC5652] and signed with the operators's End 239 Entity (EE) private key. 241 The router SHOULD verify the signature of the encapsulated PKCS#8 to 242 ensure the returned private key did in fact come from the operator, 243 but this requires that the operator also provision via the CLI or 244 include in the SignedData the RPKI CA certificate and relevant 245 operator's EE certificate(s). The router should inform the operator 246 whether or not the signature validates to a trust anchor; this 247 notification mechanism is out of scope. 249 6. Send PKCS#10 and Receive PKCS#7 251 The operator uses RPKI management tools to communicate with the 252 global RPKI system to have the appropriate CA validate the PKCS#10 253 certification request, sign the key in the PKCS#10 (i.e., certify it) 254 and generate a PKCS#7 certs-only message, as well as publishing the 255 certificate in the Global RPKI. External network connectivity may be 256 needed if the certificate is to be published in the Global RPKI. 258 After the CA certifies the key, it does two things: 260 1. Publishes the certificate in the Global RPKI. The CA must have 261 connectivity to the relevant publication point, which in turn 262 must have external network connectivity as it is part of the 263 Global RPKI. 265 2. Returns the certificate to the operator's management station, 266 packaged in a PKCS#7 certs-only message, using the corresponding 267 method by which it received the certificate request. It SHOULD 268 include the certificate chain below the TA Certificate so that 269 the router can validate the router certificate. 271 In the operator-generated method, the operator SHOULD extract the 272 certificate from the PKCS#7 certs-only message, and verify that the 273 private key it holds corresponds to the returned public key. If the 274 operator saved the PKCS#10 it can check this correspondence by 275 comparing the public key in the CSR to the public key in the returned 276 certificate. If the operator has not saved the PKCS#10, it can check 277 this correspondence by generating a signature on any data and then 278 verifying the signature using the returned certificate. 280 In the operator-generated method, the operator has already installed 281 the private key in the router (see Section 5.2). 283 7. Install Certificate 285 The operator provisions the PKCS#7 certs-only message into the router 286 over the protected channel. 288 The router SHOULD extract the certificate from the PKCS#7 certs-only 289 message and verify that the public key corresponds to the stored 290 private key. If the router stored the PKCS#10, it can check this 291 correspondence by comparing the public key in the CSR to the public 292 key in the returned certificate. If the router did not store the 293 PKCS#10, it can check this correspondence by generating a signature 294 on any data and then verifying the signature using the returned 295 certificate. The router SHOULD inform the operator whether it 296 successfully received the certificate and whether or not the keys 297 correspond; the mechanism is out of scope. 299 The router SHOULD also verify that the returned certificate validates 300 back to the installed TA Certificate, i.e., the entire chain from the 301 installed TA Certificate through subordinate CAs to the BGPsec 302 certificate validate. To perform this verification, the CA 303 certificate chain needs to be returned along with the router's 304 certificate in the PKCS#7 certs-only message. The router SHOULD 305 inform the operator whether or not the signature validates to a trust 306 anchor; this notification mechanism is out of scope. 308 NOTE: The signature on the PKCS#8 and Certificate need not be made by 309 the same entity. Signing the PKCS#8, permits more advanced 310 configurations where the entity that generates the keys is not the 311 direct CA. 313 8. Advanced Deployment Scenarios 315 More PKI-capable routers can take advantage of this increased 316 functionality and lighten the operator's burden. Typically, these 317 routers include either pre-installed manufacturer-generated 318 certificates (e.g., IEEE 802.1 AR [802.1AR]) or pre-installed 319 manufacturer-generated Pre-Shared Keys (PSK) as well as 320 PKI-enrollment functionality and transport protocol, e.g., CMC's 321 "Secure Transport" [RFC7030] or the original CMC transport protocol's 322 [RFC5273]. When the operator first establishes a protected channel 323 between the management system and the router, this pre-installed key 324 material is used to authenticate the router. 326 The operator burden shifts here to include: 328 1. Securely communicating the router's authentication material to 329 the CA prior to operator initiating the router's CSR. CAs use 330 authentication material to determine whether the router is 331 eligible to receive a certificate. Authentication material at a 332 minimum includes the router's AS number and BGP Identifier as 333 well as the router's key material, but can also include 334 additional information. Authentication material can be 335 communicated to the CA (i.e., CSRs signed by this key material 336 are issued certificates with this AS and BGP Identifier) or to 337 the router (i.e., the operator uses the vendor-supplied 338 management interface to include the AS number and BGP Identifier 339 in the router-generated CSR). 341 2. Enabling the router to communicate with the CA. While the 342 router-to-CA communications are operator-initiated, the 343 operator's management interface need not be involved in the 344 communications path. Enabling the router-to-CA connectivity MAY 345 require connections to external networks (i.e., through 346 firewalls, NATs, etc.). 348 Once configured, the operator can begin the process of enrolling the 349 router. Because the router is communicating directly with the CA, 350 there is no need for the operator to retrieve the PKCS#10 351 certification request from the router as in Section 5 or return the 352 PKCS#7 certs-only message to the router as in Section 6. Note that 353 the checks performed by the router in Section 7, namely extracting 354 the certificate from the PKCS#7 certs-only message, verifying the 355 public key corresponds to the private key, and that the returned 356 certificate validated back to an installed trust anchor, SHOULD be 357 performed. Likewise, the router SHOULD notify the operator if any of 358 these fail, but this notification mechanism is out of scope. 360 When a router is so configured, the communication with the CA SHOULD 361 be automatically re-established by the router at future times to 362 renew or rekey the certificate automatically when necessary (See 363 Section 9). This further reduces the tasks required of the operator. 365 9. Key Management 367 Key management does not only include key generation, key 368 provisioning, certificate issuance, and certificate distribution. It 369 also includes assurance of key validity, key roll-over, and key 370 preservation during router replacement. All of these 371 responsibilities persist for as long as the operator wishes to 372 operate the BGPsec-speaking router. 374 9.1. Key Validity 376 It is critical that a BGPsec speaking router is signing with a valid 377 private key at all times. To this end, the operator needs to ensure 378 the router always has a non-expired certificate. I.e. the key used 379 to sign BGPsec announcements always has an associated certificate 380 whose expiry time is after the current time. 382 Ensuring this is not terribly difficult but requires that either: 384 1. The router has a mechanism to notify the operator that the 385 certificate has an impending expiration, and/or 387 2. The operator notes the expiry time of the certificate and uses a 388 calendaring program to remind them of the expiry time, and/or 390 3. The RPKI CA warns the operator of pending expiration, and/or 392 4. The operator uses some other kind of automated process to search 393 for and track the expiry times of router certificates. 395 It is advisable that expiration warnings happen well in advance of 396 the actual expiry time. 398 Regardless of the technique used to track router certificate expiry 399 times, it is advisable to notify additional operators in the same 400 organization as the expiry time approaches, thereby ensuring that the 401 forgetfulness of one operator does not affect the entire 402 organization. 404 Depending on inter-operator relationship, it may be helpful to notify 405 a peer operator that one or more of their certificates are about to 406 expire. 408 9.2. Key Roll-Over 410 Routers that support multiple private keys also greatly increase the 411 chance that routers can continuously speak BGPsec because the new 412 private key and certificate can be obtained and distributed prior to 413 expiration of the operational key. Obviously, the router needs to 414 know when to start using the new key. Once the new key is being 415 used, having the already distributed certificate ensures continuous 416 operation. 418 More information on how to proceed with a Key Roll-Over is described 419 in [I-D.sidrops-bgpsec-rollover]. 421 9.3. Key Revocation 423 In certain circumstances, a router's BGPsec certificate may need to 424 be revoked. When this occurs, the operator needs to use the RPKI CA 425 system to revoke the certificate by placing the router's BGPsec 426 certificate on the Certificate Revocation List (CRL) as well as 427 re-keying the router's certificate. 429 When an active router key is to be revoked, the process of requesting 430 the CA to revoke, the process of the CA actually revoking the 431 router's certificate, and then the process of re-keying/renewing the 432 router's certificate, (possibly distributing a new key and 433 certificate to the router), and distributing the status, takes time 434 during which the operator must decide how they wish to maintain 435 continuity of operations, with or without the compromised private 436 key, or whether they wish to bring the router offline to address the 437 compromise. 439 Keeping the router operational and BGPsec-speaking is the ideal goal; 440 but, if operational practices do not allow this, then reconfiguring 441 the router to disable BGPsec is likely preferred to bringing the 442 router offline. 444 Routers which support more than one private key, where one is 445 operational and other(s) are soon-to-be-operational, facilitate 446 revocation events because the operator can configure the router to 447 make a soon-to-be-operational key operational, request revocation of 448 the compromised key, and then make a next generation 449 soon-to-be-operational key. Hopefully, all this can be done without 450 needing to take offline or reboot the router. For routers which 451 support only one operational key, the operators should create or 452 install the new private key, and then request revocation of the 453 certificate corresponding to the compromised private key. 455 9.4. Router Replacement 457 Currently routers often generate private keys for uses such as SSH, 458 and the private keys may not be seen or off-loaded from the router. 459 While this is good security, it creates difficulties when a routing 460 engine or whole router must be replaced in the field and all software 461 which accesses the router must be updated with the new keys. Also, 462 any network based initial contact with a new routing engine requires 463 trust in the public key presented on first contact. 465 To allow operators to quickly replace routers without requiring 466 update and distribution of the corresponding public keys in the RPKI, 467 routers SHOULD allow the private BGPsec key to be inserted via a 468 protected channel, e.g., SSH, NetConf (see [RFC6470]), SNMP. This 469 lets the operator escrow the old private key via the mechanism used 470 for operator-generated keys, see Section 5.2, such that it can be re- 471 inserted into a replacement router. The router MAY allow the private 472 key to be to be off-loaded via the protected channel, but this SHOULD 473 be paired with functionality that sets the key into a permanent non- 474 exportable state to ensure that it is not off-loaded at a future time 475 by unauthorized operations. 477 10. Security Considerations 478 The router's manual will describe whether the router supports one, 479 the other, or both of the key generation options discussed in the 480 earlier sections of this draft as well as other important security- 481 related information (e.g., how to SSH to the router). After 482 familiarizing one's self with the capabilities of the router, an 483 operator is encouraged to ensure that the router is patched with the 484 latest software updates available from the manufacturer. 486 This document defines no protocols. So, in some sense, it introduces 487 no new security considerations. However, it relies on many others 488 and the security considerations in the referenced documents should be 489 consulted; notably, those document listed in Section 1 should be 490 consulted first. PKI-relying protocols, of which BGPsec is one, have 491 many issues to consider - so many, in fact, entire books have been 492 written to address them; so listing all PKI-related security 493 considerations is neither useful nor helpful. Regardless, some boot- 494 strapping-related issues are listed here that are worth repeating: 496 Public-Private key pair generation: Mistakes here are, for all, 497 practical purposes catastrophic because PKIs rely on the pairing 498 of a difficult to generate public-private key pair with a signer; 499 all key pairs MUST be generated from a good source of non- 500 deterministic random input [RFC4086]. 502 Private key protection at rest: Mistakes here are, for all, practical 503 purposes catastrophic because disclosure of the private key allows 504 another entity to masquerade as (i.e., impersonate) the signer; 505 all private keys MUST be protected when at rest in a secure 506 fashion. Obviously, how each router protects private keys is 507 implementation specific. Likewise, the local storage format for 508 the private key is just that, a local matter. 510 Private key protection in transit: Mistakes here are, for all, 511 practical purposes catastrophic because disclosure of the private 512 key allows another entity to masquerade as (i.e., impersonate) the 513 signer; transport security is therefore strongly RECOMMENDED. The 514 level of security provided by the transport layer's security 515 mechanism SHOULD be commensurate with the strength of the BGPsec 516 key; there's no point in spending time and energy to generate an 517 excellent public-private key pair and then transmit the private 518 key in the clear or with a known-to-be-broken algorithm, as it 519 just undermines trust that the private key has been kept private. 520 Additionally, operators SHOULD ensure the transport security 521 mechanism is up to date, in order to addresses all known 522 implementation bugs. 524 Though the CA's certificate is installed on the router and used to 525 verify that the returned certificate is in fact signed by the CA, the 526 revocation status of the CA's certificate is rarely checked as the 527 router may not have global connectivity or CRL-aware software. The 528 operator MUST ensure that the installed CA certificate is valid. 530 11. IANA Considerations 532 This document has no IANA Considerations. 534 12. References 536 12.1. Normative References 538 [I-D.sidrops-bgpsec-rollover] 539 Weis, B, R. Gagliano, and K. Patel, "BGPsec Router 540 Certificate Rollover", draft-ietf-sidrops-bgpsec- 541 rollover (work in progress), December 2017. 543 [I-D.lamps-rfc5751-bis] 544 Schaad, J., Ramsdell, B, S. Turner, 545 "Secure/Multipurpose Internet Mail Extension (S/MIME) 546 Version 4.0", draft-ietf-lamps-rfc5751- 547 bis (work in progress), July 2018. 549 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 550 Requirement Levels", BCP 14, RFC 2119, DOI 551 10.17487/RFC2119, March 1997, . 554 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 555 "Randomness Requirements for Security", BCP 106, RFC 4086, 556 DOI 10.17487/RFC4086, June 2005, . 559 [RFC4253] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) 560 Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253, 561 January 2006, . 563 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 564 Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 565 10.17487/RFC4271, January 2006, . 568 [RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, 569 RFC 5652, DOI 10.17487/RFC5652, September 2009, 570 . 572 [RFC5958] Turner, S., "Asymmetric Key Packages", RFC 5958, DOI 573 10.17487/RFC5958, August 2010, . 576 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in 577 RFC 2119 Key Words", BCP 14, RFC 8174, DOI 578 10.17487/RFC8174, May 2017, . 581 [RFC8208] Turner, S. and O. Borchert, "BGPsec Algorithms, Key 582 Formats, and Signature Formats", RFC 8208, DOI 583 10.17487/RFC8208, September 2017, . 586 [RFC8209] Reynolds, M., Turner, S., and S. Kent, "A Profile for 587 BGPsec Router Certificates, Certificate Revocation Lists, 588 and Certification Requests", RFC 8209, DOI 589 10.17487/RFC8209, September 2017, . 592 [802.1AR] IEEE SA-Standards Board, "IEEE Standard for Local and 593 metropolitan area networks - Secure Device Identity", 594 December 2009, 595 . 598 12.1. Informative References 600 [RFC2585] Housley, R. and P. Hoffman, "Internet X.509 Public Key 601 Infrastructure Operational Protocols: FTP and HTTP", 602 RFC 2585, DOI 10.17487/RFC2585, May 1999, 603 . 605 [RFC3766] Orman, H. and P. Hoffman, "Determining Strengths For 606 Public Keys Used For Exchanging Symmetric Keys", BCP 86, 607 RFC 3766, DOI 10.17487/RFC3766, April 2004, 608 . 610 [RFC5273] Schaad, J. and M. Myers, "Certificate Management over CMS 611 (CMC): Transport Protocols", RFC 5273, DOI 612 10.17487/RFC5273, June 2008, . 615 [RFC5480] Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk, 616 "Elliptic Curve Cryptography Subject Public Key 617 Information", RFC 5480, DOI 10.17487/RFC5480, March 2009, 618 . 620 [RFC5647] Igoe, K. and J. Solinas, "AES Galois Counter Mode for the 621 Secure Shell Transport Layer Protocol", RFC 5647, DOI 622 10.17487/RFC5647, August 2009, . 625 [RFC5656] Stebila, D. and J. Green, "Elliptic Curve Algorithm 626 Integration in the Secure Shell Transport Layer", 627 RFC 5656, DOI 10.17487/RFC5656, December 2009, 628 . 630 [RFC5967] Turner, S., "The application/pkcs10 Media Type", RFC 5967, 631 DOI 10.17487/RFC5967, August 2010, . 634 [RFC6187] Igoe, K. and D. Stebila, "X.509v3 Certificates for Secure 635 Shell Authentication", RFC 6187, DOI 10.17487/RFC6187, 636 March 2011, . 638 [RFC6470] Bierman, A., "Network Configuration Protocol (NETCONF) 639 Base Notifications", RFC 6470, DOI 10.17487/RFC6470, 640 February 2012, . 642 [RFC6484] Kent, S., Kong, D., Seo, K., and R. Watro, "Certificate 643 Policy (CP) for the Resource Public Key Infrastructure 644 (RPKI)", BCP 173, RFC 6484, DOI 10.17487/RFC6484, February 645 2012, . 647 [RFC6668] Bider, D. and M. Baushke, "SHA-2 Data Integrity 648 Verification for the Secure Shell (SSH) Transport Layer 649 Protocol", RFC 6668, DOI 10.17487/RFC6668, July 2012, 650 . 652 [RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed., 653 "Enrollment over Secure Transport", RFC 7030, DOI 654 10.17487/RFC7030, October 2013, . 657 [RFC8205] Lepinski, M., Ed., and K. Sriram, Ed., "BGPsec Protocol 658 Specification", RFC 8205, DOI 10.17487/RFC8205, September 659 2017, . 661 [SP800-57] National Institute of Standards and Technology (NIST), 662 Special Publication 800-57: Recommendation for Key 663 Management - Part 1 (Revised), March 2007. 665 Appendix A. Management/Router Channel Security 667 Encryption, integrity, authentication, and key exchange algorithms 668 used by the protected channel SHOULD be of equal or greater strength 669 than the BGPsec keys they protect, which for the algorithm specified 670 in [RFC8208] is 128-bit; see [RFC5480] and by reference [SP800-57] 671 for information about this strength claim as well as [RFC3766] for 672 "how to determine the length of an asymmetric key as a function of a 673 symmetric key strength requirement." In other words, for the 674 encryption algorithm, do not use export grade crypto (40-56 bits of 675 security), do not use Triple DES (112 bits of security). Suggested 676 minimum algorithms would be AES-128: aes128-cbc [RFC4253] and 677 AEAD_AES_128_GCM [RFC5647] for encryption, hmac-sha2-256 [RFC6668] or 678 AESAD_AES_128_GCM [RFC5647] for integrity, ecdsa-sha2-nistp256 679 [RFC5656] for authentication, and ecdh-sha2-nistp256 [RFC5656] for 680 key exchange. 682 Some routers support the use of public key certificates and SSH. The 683 certificates used for the SSH session are different than the 684 certificates used for BGPsec. The certificates used with SSH should 685 also enable a level of security commensurate with BGPsec keys; 686 x509v3-ecdsa-sha2-nistp256 [RFC6187] could be used for 687 authentication. 689 The protected channel must provide confidentiality, authentication, 690 and integrity and replay protection. 692 Appendix B. The n00b Guide to BGPsec Key Management 694 This appendix is informative. It attempts to explain all of the PKI 695 technobabble in plainer language. 697 BGPsec speakers send signed BGPsec updates that are verified by other 698 BGPsec speakers. In PKI parlance, the senders are referred to as 699 signers and the receivers are referred to as relying parties. The 700 signers with which we are concerned here are routers signing BGPsec 701 updates. Signers use private keys to sign and relying parties use 702 the corresponding public keys, in the form of X.509 public key 703 certificates, to verify signatures. The third party involved is the 704 entity that issues the X.509 public key certificate, the 705 Certification Authority (CA). Key management is all about making 706 these key pairs and the certificates, as well as ensuring that the 707 relying parties trust that the certified public keys in fact 708 correspond to the signers' private keys. 710 The specifics of key management greatly depend on the routers as well 711 as management interfaces provided by the routers' vendor. Because of 712 these differences, it is hard to write a definitive "how to," but 713 this guide is intended to arm operators with enough information to 714 ask the right questions. The other aspect that makes this guide 715 informative is that the steps for the do-it-yourself (DIY) approach 716 involve arcane commands while the GUI-based vendor-assisted 717 management console approach will likely hide all of those commands 718 behind some button clicks. Regardless, the operator will end up with 719 a BGPsec-enabled router. Initially, we focus on the DIY approach and 720 then follow up with some information about the GUI-based approach. 722 The first step in the DIY approach is to generate a private key; but 723 in fact what you do is create a key pair; one part, the private key, 724 is kept very private and the other part, the public key, is given out 725 to verify whatever is signed. The two models for how to create the 726 key pair are the subject of this document, but it boils down to 727 either doing it on-router (router-driven) or off-router (operator- 728 driven). 730 If you are generating keys on the router (router-driven), then you 731 will need to access the router. Again, how you access the router is 732 router-specific, but generally the DIY approach uses the CLI and 733 accessing the router either directly via the router's craft port or 734 over the network on an administrative interface. If accessing the 735 router over the network be sure to do it securely (i.e., use SSHv2). 736 Once logged into the router, issue a command or a series of commands 737 that will generate the key pair for the algorithms referenced in the 738 main body of this document; consult your router's documentation for 739 the specific commands. The key generation process will yield 740 multiple files: the private key and the public key; the file format 741 varies depending on the arcane command you issued, but generally the 742 files are DER or PEM-encoded. 744 The second step is to generate the certification request, which is 745 often referred to as a certificate signing request (CSR) or PKCS#10 746 certification request, and to send it to the CA to be signed. To 747 generate the CSR, you issue some more arcane commands while logged 748 into the router; using the private key just generated to sign the 749 certification request with the algorithms referenced in the main body 750 of this document; the CSR is signed to prove to the CA that the 751 router has possession of the private key (i.e., the signature is the 752 proof-of-possession). The output of the command is the CSR file; the 753 file format varies depending on the arcane command you issued, but 754 generally the files are DER or PEM-encoded. 756 The third step is to retrieve the signed CSR from the router and send 757 it to the CA. But before sending it, you need to also send the CA 758 the subject name (i.e., "ROUTER-" followed by the AS number) and 759 serial number (i.e., the 32-bit BGP Identifier) for the router. The 760 CA needs this information to issue the certificate. How you get the 761 CSR to the CA, is beyond the scope of this document. While you are 762 still connected to the router, install the Trust Anchor (TA) for the 763 root of the PKI. At this point, you no longer need access to the 764 router for BGPsec-related initiation purposes. 766 The fourth step is for the CA to issue the certificate based on the 767 CSR you sent; the certificate will include the subject name, serial 768 number, public key, and other fields as well as being signed by the 769 CA. After the CA issues the certificate, the CA returns the 770 certificate, and posts the certificate to the RPKI repository. Check 771 that the certificate corresponds to the private key by verifying the 772 signature on the CSR sent to the CA; this is just a check to make 773 sure that the CA issued a certificate that includes a public key that 774 is the pair of the private key (i.e., the math will work when 775 verifying a signature generated by the private with the returned 776 certificate). 778 If generating the keys off-router (operator-driven), then the same 779 steps are used as the on-router key generation, (possibly with the 780 same arcane commands as those used in the on-router approach), but no 781 access to the router is needed the first three steps are done on an 782 administrative workstation: o Step 1: Generate key pair; o Step 2: 783 Create CSR and sign CSR with private key, and; o Step 3: Send CSR 784 file with the subject name and serial number to CA. 786 After the CA has returned the certificate and you have checked the 787 certificate, you need to put the private key and TA in the router. 788 Assuming the DIY approach, you will be using the CLI and accessing 789 the router either directly via the router's craft port or over the 790 network on an admin interface; if accessing the router over the 791 network make doubly sure it is done securely (i.e., use SSHv2) 792 because the private key is being moved over the network. At this 793 point, access to the router is no longer needed for BGPsec-related 794 initiation purposes. 796 NOTE: Regardless of the approach taken, the first three steps could 797 trivially be collapsed by a vendor-provided script to yield the 798 private key and the signed CSR. 800 Given a GUI-based vendor-assisted management console, then all of 801 these steps will likely be hidden behind pointing and clicking the 802 way through BGPsec-enabling the router. 804 The scenarios described above require the operator to access each 805 router, which does not scale well to large networks. An alternative 806 would be to create an image, perform the necessary steps to get the 807 private key and trust anchor on the image, and then install the image 808 via a management protocol. 810 One final word of advice; certificates include a notAfter field that 811 unsurprisingly indicates when relying parties should no longer trust 812 the certificate. To avoid having routers with expired certificates 813 follow the recommendations in the Certification Policy (CP) [RFC6484] 814 and make sure to renew the certificate at least one week prior to the 815 notAfter date. Set a calendar reminder in order not to forget! 817 Authors' Addresses 819 Randy Bush 820 IIJ / Dragon Research Labs 821 5147 Crystal Springs 822 Bainbridge Island, Washington 98110 823 US 825 Email: randy@psg.com 827 Sean Turner 828 sn3rd 830 Email: sean@sn3rd.com 832 Keyur Patel 833 Arrcus, Inc. 835 Email: keyur@arrcus.com