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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (October 20, 2017) is 2378 days in the past. Is this intentional? 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) -- Obsolete informational reference (is this intentional?): RFC 5751 (Obsoleted by RFC 8551) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). 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: April 23, 2018 sn3rd 6 K. Patel 7 Arrcus, Inc. 8 October 20, 2017 10 Router Keying for BGPsec 11 draft-ietf-sidr-rtr-keying-14 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", "MAY", and "OPTIONAL" are to 26 be interpreted as described in RFC 2119 [RFC2119] only when they 27 appear in all upper case. They may also appear in lower or mixed 28 case as English words, without normative meaning. 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) 2017 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 . . . . . . . . . . . . . . . . . . 4 70 5.2. Operator-Generated Keys . . . . . . . . . . . . . . . . . 5 71 5.2.1. Using PKCS#8 to Transfer Public Key . . . . . . . . . 5 72 6. Send PKCS#10 and Receive PKCS#7 . . . . . . . . . . . . . . . 5 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 . . . . . . . . . . . . . . . . . . . . . . 8 78 9.3. Key Revocation . . . . . . . . . . . . . . . . . . . . . . 9 79 9.4. Router Replacement . . . . . . . . . . . . . . . . . . . . 9 80 10. Security Considerations . . . . . . . . . . . . . . . . . . . 10 81 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 82 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 83 12.1. Normative References . . . . . . . . . . . . . . . . . . 11 84 12.1. Informative References . . . . . . . . . . . . . . . . . 12 85 Appendix A. Management/Router Channel Security . . . . . . . . . 14 86 Appendix B. The n00b Guide to BGPsec Key Management . . . . . . . 14 87 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 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 sub-methods, 97 router-driven and operator-driven. 99 These two sub-methods differ in where the keys are generated: on the 100 router in the router-driven method, and elsewhere in the operator- 101 driven method. Routers are required to support at least one of the 102 methods in order to work in various deployment environments. Some 103 routers may not allow the private key to be off-loaded while others 104 may. While off-loading private keys would ease swapping of routing 105 engines, exposure of private keys is a well known security risk. 107 In the operator-driven method, the operator generates the private/ 108 public key-pair and sends it to the router. 110 In the router-driven method, the router generates its own public/ 111 private key-pair. 113 The router-driven model mirrors the model used by traditional PKI 114 subscribers; the private key never leaves trusted storage (e.g., 115 Hardware Security Module). This is by design and supports classic 116 PKI Certification Policies for (often human) subscribers which 117 require the private key only ever be controlled by the subscriber to 118 ensure that no one can impersonate the subscriber. For non-humans, 119 this model does not always work. For example, when an operator wants 120 to support hot-swappable routers the same private key needs to be 121 installed in the soon-to-be online router that was used by the the 122 soon-to-be offline router. This motivated the operator-driven model. 124 The remainder of this document describes how operators can use the 125 two methods to provision new and existing routers. The methods 126 described involve the operator configuring the two end points and 127 acting as the intermediary. Section 7 describes a method that 128 requires more capable routers. 130 Useful References: [RFC8205] describes gritty details, [RFC8209] 131 specifies the format for the PKCS #10 request, and [RFC8208] 132 specifies the algorithms used to generate the signature. 134 2. Management / Router Communication 136 Operators are free to use either the router-driven or operator-driven 137 method as supported by the platform. Regardless of the method 138 chosen, operators first establish a secure communication channel 139 between the management system and the router. How this channel is 140 established is router-specific and is beyond scope of this document. 141 Though other configuration mechanisms might be used, e.g. NetConf 142 (see [RFC6470]); for simplicity, in this document, the communication 143 channel between the management platform and the router is assumed to 144 be an SSH-protected CLI. See Appendix A for security considerations 145 for this channel. 147 3. Exchange Certificates 149 A number of options exist for the operator management station to 150 exchange PKI-related information with routers and with the RPKI 151 including: 153 - Use application/pkcs10 media type [RFC5967] to extract certificate 154 requests and application/pkcs7-mime [RFC5751] to return the issued 155 certificate, 157 - Use FTP or HTTP per [RFC2585], and 159 - Use Enrollment over Secure Transport (EST) protocol per [RFC7030]. 161 4. Set-Up 163 To start, the operator uses the communication channel to install the 164 appropriate RPKI Trust Anchor' Certificate (TA Cert) in the router. 165 This will later enable the router to validate the router certificate 166 returned in the PKCS#7. 168 The operator also configures the Autonomous System (AS) number to be 169 used in the generated router certificate. This may be the sole AS 170 configured on the router, or an operator choice if the router is 171 configured with multiple ASs. 173 The operator configures or extracts from the router the BGP RouterID 174 to be used in the generated certificate. In the case where the 175 operator has chosen not to use unique per-router certificates, a 176 RouterID of 0 may be used. 178 5. Generate PKCS#10 180 The private key, and hence the PKCS#10 request, which is sometimes 181 referred to as a Certificate Signing Request (CSR), may be generated 182 by the router or by the operator. 184 5.1. Router-Generated Keys 186 In the router-generated method, once the protected session is 187 established and the initial Set-Up (Section 4) performed, the 188 operator issues a command or commands for the router to generate the 189 public/private key pair, to generate the PKCS#10 request, and to sign 190 the PKCS#10 with the private key. Once generated, the PKCS#10 is 191 returned to the operator over the protected channel. 193 The operator adds the chosen AS number and the RouterID to send to 194 the RPKI CA for the CA to certify. 196 NOTE: If a router was to communicate directly with a CA to have the 197 CA certify the PKCS#10, there would be no way for the CA to 198 authenticate the router. As the operator knows the authenticity of 199 the router, the operator mediates the communication with the CA. 201 5.2. Operator-Generated Keys 203 In the operator-generated method, the operator generates the 204 public/private key pair on a management station and installs the 205 private key into the router over the protected channel. Beware that 206 experience has shown that copy and paste from a management station to 207 a router can be unreliable for long texts. 209 The operator then creates and signs the PKCS#10 with the private key, 210 and adds the chosen AS number and RouterID to be sent to the RPKI CA 211 for the CA to certify. 213 5.2.1. Using PKCS#8 to Transfer Public Key 215 A private key encapsulated in a PKCS #8 [RFC5958] should be further 216 encapsulated in Cryptographic Message Syntax (CMS) SignedData 217 [RFC5652] and signed with the AS's End Entity (EE) private key. 219 The router SHOULD verify the signature of the encapsulated PKCS#8 to 220 ensure the returned private key did in fact come from the operator, 221 but this requires that the operator also provision via the CLI or 222 include in the SignedData the RPKI CA certificate and relevant AS's 223 EE certificate(s). The router should inform the operator whether or 224 not the signature validates to a trust anchor; this notification 225 mechanism is out of scope. 227 6. Send PKCS#10 and Receive PKCS#7 229 The operator uses RPKI management tools to communicate with the 230 global RPKI system to have the appropriate CA validate the PKCS#10 231 request, sign the key in the PKCS#10 (i.e., certify it) and generated 232 PKCS#7 response, as well as publishing the certificate in the Global 233 RPKI. External network connectivity may be needed if the certificate 234 is to be published in the Global RPKI. 236 After the CA certifies the key, it does two things: 238 1. Publishes the certificate in the Global RPKI. The CA must have 239 connectivity to the relevant publication point, which in turn 240 must have external network connectivity as it is part of the 241 Global RPKI. 243 2. Returns the certificate to the operator's management station, 244 packaged in a PKCS#7, using the corresponding method by which it 245 received the certificate request. It SHOULD include the 246 certificate chain below the TA Certificate so that the router can 247 validate the router certificate. 249 In the operator-generated method, the operator SHOULD extract the 250 certificate from the PKCS#7, and verify that the private key it holds 251 corresponds to the returned public key. 253 In the operator-generated method, the operator has already installed 254 the private key in the router (see Section 5.2). 256 7. Install Certificate 258 The operator provisions the PKCS#7 into the router over the secure 259 channel. 261 The router SHOULD extract the certificate from the PKCS#7 and verify 262 that the public key corresponds to the stored private key. The 263 router SHOULD inform the operator whether it successfully received 264 the certificate and whether or not the keys correspond; the mechanism 265 is out of scope. 267 The router SHOULD also verify that the returned certificate validates 268 back to the installed TA Certificate, i.e., the entire chain from the 269 installed TA Certificate through subordinate CAs to the BGPsec 270 certificate validate. To perform this verification the CA 271 certificate chain needs to be returned along with the router's 272 certificate in the PKCS#7. The router SHOULD inform the operator 273 whether or not the signature validates to a trust anchor; this 274 notification mechanism is out of scope. 276 Even if the operator cannot extract the private key from the router, 277 this signature still provides a linkage between a private key and a 278 router. That is the operator can verify the proof of possession 279 (POP), as required by [RFC6484]. 281 NOTE: The signature on the PKCS#8 and Certificate need not be made by 282 the same entity. Signing the PKCS#8, permits more advanced 283 configurations where the entity that generates the keys is not the 284 direct CA. 286 8. Advanced Deployment Scenarios 288 More PKI-capable routers can take advantage of this increased 289 functionality and lighten the operator's burden. Typically, these 290 routers include either pre-installed manufacturer-generated 291 certificates (e.g., IEEE 802.1 AR [802.1AR]) or pre-installed 292 manufacturer-generated Pre-Shared Keys (PSK) as well as PKI- 293 enrollment functionality and transport protocol, e.g., CMC's "Secure 294 Transport" [RFC7030] or the original CMC transport protocol's 295 [RFC5273]. When the operator first establishes a secure 296 communication channel between the management system and the router, 297 this pre-installed key material is used to authenticate the router. 299 The operator burden shifts here to include: 301 1. Securely communicating the router's authentication material to 302 the CA prior to operator initiating the router's CSR. CAs use 303 authentication material to determine whether the router is 304 eligible to receive a certificate. Authentication material at a 305 minimum includes the router's AS number and RouterID as well as 306 the router's key material, but can also include additional 307 information. Authentication material can be communicated to the 308 CA (i.e., CSRs signed by this key material are issued 309 certificates with this AS and RouterID) or to the router (i.e., 310 the operator uses the vendor-supplied management interface to 311 include the AS number and routerID in the router-generated CSR). 313 2. Enabling the router to communicate with the CA. While the 314 router-to-CA communications are operator-initiated, the 315 operator's management interface need not be involved in the 316 communications path. Enabling the router-to-CA connectivity MAY 317 require connections to external networks (i.e., through 318 firewalls, NATs, etc.). 320 Once configured, the operator can begin the process of enrolling the 321 router. Because the router is communicating directly with the CA, 322 there is no need for the operator to retrieve the PKCS#10 from the 323 router or return the PKCS#7 to the router as in Section 6. Note that 324 the checks performed by the router, namely extracting the certificate 325 from the PKCS#7, verifying the public key corresponds to the private 326 key, and that the returned certificate validated back to an installed 327 trust anchor, SHOULD be performed. Likewise, the router SHOULD 328 notify the operator if any of these fail, but this notification 329 mechanism is out of scope. 331 When a router is so configured the communication with the CA SHOULD 332 be automatically re-established by the router at future times to 333 renew or rekey the certificate automatically when necessary (See 334 Section 8). This further reduces the tasks required of the operator. 336 9. Key Management 338 Key management does not only include key generation, key 339 provisioning, certificate issuance, and certificate distribution. It 340 also includes assurance of key validity, key roll-over, and key 341 preservation during router replacement. All of these 342 responsibilities persist for as long as the operator wishes to 343 operate the BGPsec-speaking router. 345 9.1. Key Validity 347 It is critical that a BGPsec speaking router is signing with a valid 348 private key at all times. To this end, the operator needs to ensure 349 the router always has a non-expired certificate. I.e. the key used 350 to sign BGPsec announcements always has an associated certificate 351 whose expiry time is after the current time. 353 Ensuring this is not terribly difficult but requires that either: 355 1. The router has a mechanism to notify the operator that the 356 certificate has an impending expiration, and/or 358 2. The operator notes the expiry time of the certificate and uses a 359 calendaring program to remind them of the expiry time, and/or 361 3. The RPKI CA warns the operator of pending expiration, and/or 363 4. Use some other kind of automated process to search for and track 364 the expiry times of router certificates. 366 It is advisable that expiration warnings happen well in advance of 367 the actual expiry time. 369 Regardless of the technique used to track router certificate expiry 370 times, it is advisable to notify additional operators in the same 371 organization as the expiry time approaches thereby ensuring that the 372 forgetfulness of one operator does not affect the entire 373 organization. 375 Depending on inter-operator relationship, it may be helpful to notify 376 a peer operator that one or more of their certificates are about to 377 expire. 379 9.2. Key Roll-Over 381 Routers that support multiple private keys also greatly increase the 382 chance that routers can continuously speak BGPsec because the new 383 private key and certificate can be obtained and distributed prior to 384 expiration of the operational key. Obviously, the router needs to 385 know when to start using the new key. Once the new key is being 386 used, having the already distributed certificate ensures continuous 387 operation. 389 More information on how to proceed with a Key Roll-Over is described 390 in [I-D.sidrops-bgpsec-rollover]. 392 9.3. Key Revocation 394 Certain unfortunate circumstances may occur causing a need to revoke 395 a router's BGPsec certificate. When this occurs, the operator needs 396 to use the RPKI CA system to revoke the certificate by placing the 397 router's BGPsec certificate on the Certificate Revocation List (CRL) 398 as well as re-keying the router's certificate. 400 When an active router key is to be revoked, the process of requesting 401 the CA to revoke, the process of the CA actually revoking the 402 router's certificate, and then the process of re-keying/renewing the 403 router's certificate, (possibly distributing a new key and 404 certificate to the router), and distributing the status takes time 405 during which the operator must decide how they wish to maintain 406 continuity of operations, with or without the compromised private 407 key, or whether they wish to bring the router offline to address the 408 compromise. 410 Keeping the router operational and BGPsec-speaking is the ideal goal, 411 but if operational practices do not allow this then reconfiguring the 412 router to disabling BGPsec is likely preferred to bringing the router 413 offline. 415 Routers which support more than one private key, where one is 416 operational and other(s) are soon-to-be-operational, facilitate 417 revocation events because the operator can configure the router to 418 make a soon-to-be-operational key operational, request revocation of 419 the compromised key, and then make a next generation soon-to-be- 420 operational key, all hopefully without needing to take offline or 421 reboot the router. For routers which support only one operational 422 key, the operators should create or install the new private key, and 423 then request revocation of the certificate corresponding to the 424 compromised private key. 426 9.4. Router Replacement 428 Currently routers often generate private keys for uses such as SSH, 429 and the private keys may not be seen or off-loaded from the router. 431 While this is good security, it creates difficulties when a routing 432 engine or whole router must be replaced in the field and all software 433 which accesses the router must be updated with the new keys. Also, 434 any network based initial contact with a new routing engine requires 435 trust in the public key presented on first contact. 437 To allow operators to quickly replace routers without requiring 438 update and distribution of the corresponding public keys in the RPKI, 439 routers SHOULD allow the private BGPsec key to inserted via a 440 protected session, e.g., SSH, NetConf (see [RFC6470]), SNMP. This 441 lets the operator escrow the old private key via the mechanism used 442 for operator-generated keys, see Section 5.2, such that it can be re- 443 inserted into a replacement router. The router MAY allow the private 444 key to be to be off-loaded via the protected session, but this SHOULD 445 be paired with functionality that sets the key into a permanent non- 446 exportable state to ensure that it is not off-loaded at a future time 447 by unauthorized operations. 449 10. Security Considerations 451 The router's manual will describe whether the router supports one, 452 the other, or both of the key generation options discussed in the 453 earlier sections of this draft as well as other important security- 454 related information (e.g., how to SSH to the router). After 455 familiarizing one's self with the capabilities of the router, 456 operators are encouraged to ensure that the router is patched with 457 the latest software updates available from the manufacturer. 459 This document defines no protocols so in some sense introduces no new 460 security considerations. However, it relies on many others and the 461 security considerations in the referenced documents should be 462 consulted; notably, those document listed in Section 1 should be 463 consulted first. PKI-relying protocols, of which BGPsec is one, have 464 many issues to consider so many in fact entire books have been 465 written to address them; so listing all PKI-related security 466 considerations is neither useful nor helpful; regardless, some boot- 467 strapping-related issues are listed here that are worth repeating: 469 Public-Private key pair generation: Mistakes here are for all 470 practical purposes catastrophic because PKIs rely on the pairing 471 of a difficult to generate public-private key pair with a signer; 472 all key pairs MUST be generated from a good source of non- 473 deterministic random input [RFC4086]. 475 Private key protection at rest: Mistakes here are for all practical 476 purposes catastrophic because disclosure of the private key allows 477 another entity to masquerade as (i.e., impersonate) the signer; 478 all private keys MUST be protected when at rest in a secure 479 fashion. Obviously, how each router protects private keys is 480 implementation specific. Likewise, the local storage format for 481 the private key is just that, a local matter. 483 Private key protection in transit: Mistakes here are for all 484 practical purposes catastrophic because disclosure of the private 485 key allows another entity to masquerade as (i.e., impersonate) the 486 signer; transport security is therefore strongly RECOMMENDED. The 487 level of security provided by the transport layer's security 488 mechanism SHOULD be commensurate with the strength of the BGPsec 489 key; there's no point in spending time and energy to generate an 490 excellent public-private key pair and then transmit the private 491 key in the clear or with a known-to-be-broken algorithm, as it 492 just undermines trust that the private key has been kept private. 493 Additionally, operators SHOULD ensure the transport security 494 mechanism is up to date, in order to addresses all known 495 implementation bugs. 497 SSH key management is known, in some cases, to be lax 498 [I-D.ylonen-sshkeybcp]; employees that no longer need access to 499 routers SHOULD be removed the router to ensure only those authorized 500 have access to a router. 502 Though the CA's certificate is installed on the router and used to 503 verify that the returned certificate is in fact signed by the CA, the 504 revocation status of the CA's certificate is rarely checked as the 505 router may not have global connectivity or CRL-aware software. The 506 operator MUST ensure that installed CA certificate is valid. 508 11. IANA Considerations 510 This document has no IANA Considerations. 512 12. References 514 12.1. Normative References 516 [I-D.sidrops-bgpsec-rollover] 517 Weis, B, R. Gagliano, and K. Patel, "BGPsec Router 518 Certificate Rollover", draft-ietf-sidrops-bgpsec- 519 rollover (work in progress), October 2017. 521 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 522 Requirement Levels", BCP 14, RFC 2119, DOI 523 10.17487/RFC2119, March 1997, . 526 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 527 "Randomness Requirements for Security", BCP 106, RFC 4086, 528 DOI 10.17487/RFC4086, June 2005, . 531 [RFC4253] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) 532 Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253, 533 January 2006, . 535 [RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, 536 RFC 5652, DOI 10.17487/RFC5652, September 2009, 537 . 539 [RFC5958] Turner, S., "Asymmetric Key Packages", RFC 5958, DOI 540 10.17487/RFC5958, August 2010, . 543 [RFC8208] Turner, S. and O. Borchert, "BGPsec Algorithms, Key 544 Formats, and Signature Formats", RFC 8208, DOI 545 10.17487/RFC8208, September 2017, . 548 [RFC8209] Reynolds, M., Turner, S., and S. Kent, "A Profile for 549 BGPsec Router Certificates, Certificate Revocation Lists, 550 and Certification Requests", RFC 8209, DOI 551 10.17487/RFC8209, September 2017, . 554 [802.1AR] IEEE SA-Standards Board, "IEEE Standard for Local and 555 metropolitan area networks - Secure Device Identity", 556 December 2009, 557 . 560 12.1. Informative References 562 [I-D.ylonen-sshkeybcp] 563 Ylonen, T. and G. Kent, "Managing SSH Keys for Automated 564 Access - Current Recommended Practice", draft-ylonen- 565 sshkeybcp (work in progress), April 2013. 567 [RFC2585] Housley, R. and P. Hoffman, "Internet X.509 Public Key 568 Infrastructure Operational Protocols: FTP and HTTP", 569 RFC 2585, DOI 10.17487/RFC2585, May 1999, 570 . 572 [RFC3766] Orman, H. and P. Hoffman, "Determining Strengths For 573 Public Keys Used For Exchanging Symmetric Keys", BCP 86, 574 RFC 3766, DOI 10.17487/RFC3766, April 2004, 575 . 577 [RFC5273] Schaad, J. and M. Myers, "Certificate Management over CMS 578 (CMC): Transport Protocols", RFC 5273, DOI 579 10.17487/RFC5273, June 2008, . 582 [RFC5480] Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk, 583 "Elliptic Curve Cryptography Subject Public Key 584 Information", RFC 5480, DOI 10.17487/RFC5480, March 2009, 585 . 587 [RFC5647] Igoe, K. and J. Solinas, "AES Galois Counter Mode for the 588 Secure Shell Transport Layer Protocol", RFC 5647, DOI 589 10.17487/RFC5647, August 2009, . 592 [RFC5656] Stebila, D. and J. Green, "Elliptic Curve Algorithm 593 Integration in the Secure Shell Transport Layer", 594 RFC 5656, DOI 10.17487/RFC5656, December 2009, 595 . 597 [RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet 598 Mail Extensions (S/MIME) Version 3.2 Message 599 Specification", RFC 5751, DOI 10.17487/RFC5751, January 600 2010, . 602 [RFC5967] Turner, S., "The application/pkcs10 Media Type", RFC 5967, 603 DOI 10.17487/RFC5967, August 2010, . 606 [RFC6187] Igoe, K. and D. Stebila, "X.509v3 Certificates for Secure 607 Shell Authentication", RFC 6187, DOI 10.17487/RFC6187, 608 March 2011, . 610 [RFC6470] Bierman, A., "Network Configuration Protocol (NETCONF) 611 Base Notifications", RFC 6470, DOI 10.17487/RFC6470, 612 February 2012, . 614 [RFC6484] Kent, S., Kong, D., Seo, K., and R. Watro, "Certificate 615 Policy (CP) for the Resource Public Key Infrastructure 616 (RPKI)", BCP 173, RFC 6484, DOI 10.17487/RFC6484, February 617 2012, . 619 [RFC6668] Bider, D. and M. Baushke, "SHA-2 Data Integrity 620 Verification for the Secure Shell (SSH) Transport Layer 621 Protocol", RFC 6668, DOI 10.17487/RFC6668, July 2012, 622 . 624 [RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed., 625 "Enrollment over Secure Transport", RFC 7030, DOI 626 10.17487/RFC7030, October 2013, . 629 [RFC8205] Lepinski, M., Ed., and K. Sriram, Ed., "BGPsec Protocol 630 Specification", RFC 8205, DOI 10.17487/RFC8205, September 631 2017, . 633 [SP800-57] National Institute of Standards and Technology (NIST), 634 Special Publication 800-57: Recommendation for Key 635 Management - Part 1 (Revised), March 2007. 637 Appendix A. Management/Router Channel Security 639 Encryption, integrity, authentication, and key exchange algorithms 640 used by the secure communication channel SHOULD be of equal or 641 greater strength than the BGPsec keys they protect, which for the 642 algorithm specified in [RFC8208] is 128-bit; see [RFC5480] and by 643 reference [SP800-57] for information about this strength claim as 644 well as [RFC3766] for "how to determine the length of an asymmetric 645 key as a function of a symmetric key strength requirement." In other 646 words, for the encryption algorithm, do not use export grade crypto 647 (40-56 bits of security), do not use Triple DES (112 bits of 648 security). Suggested minimum algorithms would be AES-128: aes128-cbc 649 [RFC4253] and AEAD_AES_128_GCM [RFC5647] for encryption, hmac-sha2- 650 256 [RFC6668] or AESAD_AES_128_GCM [RFC5647] for integrity, ecdsa- 651 sha2-nistp256 [RFC5656] for authentication, and ecdh-sha2-nistp256 652 [RFC5656] for key exchange. 654 Some routers support the use of public key certificates and SSH. The 655 certificates used for the SSH session are different than the 656 certificates used for BGPsec. The certificates used with SSH should 657 also enable a level of security commensurate with BGPsec keys; 658 x509v3-ecdsa-sha2-nistp256 [RFC6187] could be used for 659 authentication. 661 Appendix B. The n00b Guide to BGPsec Key Management 663 This appendix is informative. It attempts to explain all of the PKI 664 technobabble in plainer language. 666 BGPsec speakers send signed BGPsec updates that are verified by other 667 BGPsec speakers. In PKI parlance, the senders are referred to as 668 signers and the receivers are referred to as relying parties. The 669 signers with which we are concerned here are routers signing BGPsec 670 updates. Signers use private keys to sign and relying parties use 671 the corresponding public keys, in the form of X.509 public key 672 certificates, to verify signatures. The third party involved is the 673 entity that issues the X.509 public key certificate, the 674 Certification Authority (CA). Key management is all about making 675 these key pairs and the certificates, as well as ensuring that the 676 relying parties trust that the certified public keys in fact 677 correspond to the signers' private keys. 679 The specifics of key management greatly depend on the routers as well 680 as management interfaces provided by the routers' vendor. Because of 681 these differences, it is hard to write a definitive "how to," but 682 this guide is intended to arm operators with enough information to 683 ask the right questions. The other aspect that makes this guide 684 informative is that the steps for the do-it-yourself (DIY) approach 685 involve arcane commands while the GUI-based vendor-assisted 686 management console approach will likely hide all of those commands 687 behind some button clicks. Regardless, the operator will end up with 688 a BGPsec-enabled router. Initially, we focus on the DIY approach and 689 then follow up with some information about the GUI-based approach. 691 The first step in the DIY approach is to generate a private key; but 692 in fact what you do is create a key pair; one part, the private key, 693 is kept very private and the other part, the public key, is given out 694 to verify whatever is signed. The two models for how to create the 695 key pair are the subject of this document, but it boils down to 696 either doing it on-router (router-driven) or off-router (operator- 697 driven). 699 If you are generating keys on the router (router-driven), then you 700 will need to access the router. Again, how you access the router is 701 router-specific, but generally the DIY approach uses the CLI and 702 accessing the router either directly via the router's craft port or 703 over the network on an administrative interface. If accessing the 704 router over the network be sure to do it securely (i.e., use SSHv2). 705 Once logged into the router, issue a command or a series of commands 706 that will generate the key pair for the algorithms noted in the main 707 body of this document; consult your router's documentation for the 708 specific commands. The key generation process will yield multiple 709 files: the private key and the public key; the file format varies 710 depending on the arcane command you issued, but generally the files 711 are DER or PEM-encoded. 713 The second step is to generate the certification request, which is 714 often referred to as a certificate signing request (CSR) or PKCS#10, 715 and to send it to the CA to be signed. To generate the CSR, you 716 issue some more arcane commands while logged into the router; using 717 the private key just generated to sign the certification request with 718 the algorithms specified in the main body of this document; the CSR 719 is signed to prove to the CA that the router has possession of the 720 private key (i.e., the signature is the proof-of-possession). The 721 output of the command is the CSR file; the file format varies 722 depending on the arcane command you issued, but generally the files 723 are DER or PEM-encoded. 725 The third step is to retrieve the signed CSR from the router and send 726 it to the CA. But before sending it, you need to also send the CA 727 the subject name and serial number for the router. The CA needs this 728 information to issue the certificate. How you get the CSR to the CA, 729 is beyond the scope of this document. While you are still connected 730 to the router, install the Trust Anchor (TA) for the root of the PKI. 731 At this point, you no longer need access to the router for BGPsec- 732 related initiation purposes. 734 The fourth step is for the CA to issue the certificate based on the 735 CSR you sent; the certificate will include the subject name, serial 736 number, public key, and other fields as well as being signed by the 737 CA. After the CA issues the certificate, the CA returns the 738 certificate, and posts the certificate to the RPKI repository. Check 739 that the certificate corresponds to the private key by verifying the 740 signature on the CSR sent to the CA; this is just a check to make 741 sure that the CA issued a certificate corresponding to the private 742 key on the router. 744 If generating the keys off-router (operator-driven), then the same 745 steps are used as the on-router key generation, (possibly with the 746 same arcane commands as those used in the on-router approach), but no 747 access to the router is needed the first three steps are done on an 748 administrative workstation: o Step 1: Generate key pair; o Step 2: 749 Create CSR and sign CSR with private key, and; o Step 3: Send CSR 750 file with the subject name and serial number to CA. 752 After the CA has returned the certificate and you have checked the 753 certificate, you need to put the private key and TA in the router. 754 Assuming the DIY approach, you will be using the CLI and accessing 755 the router either directly via the router's craft port or over the 756 network on an admin interface; if accessing the router over the 757 network make doubly sure it is done securely (i.e., use SSHv2) 758 because the private key is being moved over the network. At this 759 point, access to the router is no longer needed for BGPsec-related 760 initiation purposes. 762 NOTE: Regardless of the approach taken, the first three steps could 763 trivially be collapsed by a vendor-provided script to yield the 764 private key and the signed CSR. 766 Given a GUI-based vendor-assisted management console, then all of 767 these steps will likely be hidden behind pointing and clicking the 768 way through GPsec-enabling the router. 770 The scenarios described above require the operator to access each 771 router, which does not scale well to large networks. An alternative 772 would be to create an image, perform the necessary steps to get the 773 private key and trust anchor on the image, and then install the image 774 via a management protocol. 776 One final word of advice; certificates include a notAfter field that 777 unsurprisingly indicates when relying parties should no longer trust 778 the certificate. To avoid having routers with expired certificates 779 follow the recommendations in the Certification Policy (CP) [RFC6484] 780 and make sure to renew the certificate at least one week prior to the 781 notAfter date. Set a calendar reminder in order not to forget! 783 Authors' Addresses 785 Randy Bush 786 IIJ / Dragon Research Labs 787 5147 Crystal Springs 788 Bainbridge Island, Washington 98110 789 US 791 Email: randy@psg.com 793 Sean Turner 794 sn3rd 796 Email: sean@sn3rd.com 798 Keyur Patel 799 Arrcus, Inc. 801 Email: keyur@arrcus.com