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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: March 25, 2019 sn3rd 6 K. Patel 7 Arrcus, Inc. 8 September 21, 2018 10 Router Keying for BGPsec 11 draft-ietf-sidrops-rtr-keying-00 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 . . . . . . . . . 15 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 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 (i.e., 127 the management station and the router) and acting as the 128 intermediary. Section 7 describes a method that requires more 129 capable routers. 131 Useful References: [RFC8205] describes gritty details, [RFC8209] 132 specifies the format for the PKCS#10 certification request, and 133 [RFC8208] specifies the algorithms used to generate the PKCS#10's 134 signature. 136 2. Management / Router Communication 138 Operators are free to use either the router-driven or operator-driven 139 method as supported by the platform. Regardless of the method 140 chosen, operators first establish a protected channel between the 141 management system and the router. How this protected channel is 142 established is router-specific and is beyond scope of this document. 143 Though other configuration mechanisms might be used, e.g. NetConf 144 (see [RFC6470]); for simplicity, in this document, the protected 145 channel between the management platform and the router is assumed to 146 be an SSH-protected CLI. See Appendix A for security considerations 147 for this protected channel. 149 3. Exchange Certificates 151 A number of options exist for the operator management station to 152 exchange PKI-related information with routers and with the RPKI 153 including: 155 - Use application/pkcs10 media type [RFC5967] to extract certificate 156 requests and application/pkcs7-mime [I-D.lamps-rfc5751-bis] to return 157 the issued certificate, 159 - Use FTP or HTTP per [RFC2585], and 161 - Use Enrollment over Secure Transport (EST) protocol per [RFC7030]. 163 4. Set-Up 165 To start, the operator uses the protected channel to install the 166 appropriate RPKI Trust Anchor's Certificate (TA Cert) in the router. 167 This will later enable the router to validate the router certificate 168 returned in the PKCS#7 certs-only message [I-D.lamps-rfc5751-bis]. 170 The operator also configures the Autonomous System (AS) number to be 171 used in the generated router certificate. This may be the sole AS 172 configured on the router, or an operator choice if the router is 173 configured with multiple ASs. A router with multiple ASs can be 174 configured with multiple router certificates by following the process 175 of this document for each desired certificate. 177 The operator configures or extracts from the router the BGP 178 Identifier [RFC4271] to be used in the generated router certificate. 179 In the case where the operator has chosen not to use unique per- 180 router certificates, a BGP Identifier of 0 may be used. 182 5. Generate PKCS#10 184 The private key, and hence the PKCS#10 certification request, which 185 is sometimes referred to as a Certificate Signing Request (CSR), may 186 be generated by the router or by the operator. 188 The PKCS#10 request SHOULD be saved to enable verifying that the 189 returned public key in the certificate corresponds to the private 190 used to generate the signature on the CSR. 192 NOTE: The PKCS#10 certification request does not include the AS 193 number or the BGP Identifier for the router certificate. Therefore, 194 the operator transmits the AS it has chosen or the router and the BGP 195 Identifier as well when it sends the CSR to the CA. 197 5.1. Router-Generated Keys 199 In the router-generated method, once the protected channel is 200 established and the initial Set-Up (Section 4) performed, the 201 operator issues a command or commands for the router to generate the 202 public/private key pair, to generate the PKCS#10 certification 203 request, and to sign the PKCS#10 certification request with the 204 private key. Once generated, the PKCS#10 certification request is 205 returned to the operator over the protected channel. 207 The operator includes the chosen AS number and the BGP Identifier 208 when it sends the CSR to the CA. 210 NOTE: If a router were to communicate directly with a CA to have the 211 CA certify the PKCS#10 certification request, there would be no way 212 for the CA to authenticate the router. As the operator knows the 213 authenticity of the router, the operator mediates the communication 214 with the CA. 216 5.2. Operator-Generated Keys 218 In the operator-generated method, the operator generates the 219 public/private key pair on a management station and installs the 220 private key into the router over the protected channel. Beware that 221 experience has shown that copy and paste from a management station to 222 a router can be unreliable for long texts. 224 The operator then creates and signs the PKCS#10 certification request 225 with the private key; the operator includes the chosen AS number and 226 the BGP Identifier when it sends the CSR to the CA. 228 Even if the operator cannot extract the private key from the router, 229 this signature still provides a linkage between a private key and a 230 router. That is the operator can verify the proof of possession 231 (POP), as required by [RFC6484]. 233 5.2.1. Using PKCS#8 to Transfer Private Key 235 A private key can be encapsulated in a PKCS#8 Asymmetric Key Package 236 [RFC5958] and should be further encapsulated in Cryptographic Message 237 Syntax (CMS) SignedData [RFC5652] and signed with the AS's End Entity 238 (EE) private key. 240 The router SHOULD verify the signature of the encapsulated PKCS#8 to 241 ensure the returned private key did in fact come from the operator, 242 but this requires that the operator also provision via the CLI or 243 include in the SignedData the RPKI CA certificate and relevant AS's 244 EE certificate(s). The router should inform the operator whether or 245 not the signature validates to a trust anchor; this notification 246 mechanism is out of scope. 248 6. Send PKCS#10 and Receive PKCS#7 250 The operator uses RPKI management tools to communicate with the 251 global RPKI system to have the appropriate CA validate the PKCS#10 252 certification request, sign the key in the PKCS#10 (i.e., certify it) 253 and generate a PKCS#7 certs-only message, as well as publishing the 254 certificate in the Global RPKI. External network connectivity may be 255 needed if the certificate is to be published in the Global RPKI. 257 After the CA certifies the key, it does two things: 259 1. Publishes the certificate in the Global RPKI. The CA must have 260 connectivity to the relevant publication point, which in turn 261 must have external network connectivity as it is part of the 262 Global RPKI. 264 2. Returns the certificate to the operator's management station, 265 packaged in a PKCS#7 certs-only message, using the corresponding 266 method by which it received the certificate request. It SHOULD 267 include the certificate chain below the TA Certificate so that 268 the router can validate the router certificate. 270 In the operator-generated method, the operator SHOULD extract the 271 certificate from the PKCS#7 certs-only message, and verify that the 272 private key it holds corresponds to the returned public key. If the 273 operator saved the PKCS#10 it can check this correspondence by 274 comparing the public key in the CSR to the public key in the returned 275 certificate. If the operator has not saved the PKCS#10, it can check 276 this correspondence by generating a signature on any data and then 277 verifying the signature using the returned certificate. 279 In the operator-generated method, the operator has already installed 280 the private key in the router (see Section 5.2). 282 7. Install Certificate 284 The operator provisions the PKCS#7 certs-only message into the router 285 over the protected channel. 287 The router SHOULD extract the certificate from the PKCS#7 certs-ony 288 message and verify that the public key corresponds to the stored 289 private key. If the router stored the PKCS#10, it can check this 290 correspondence by comparing the public key in the CSR to the public 291 key in the returned certificate. If the router did not store the 292 PKCS#10, it can check this correspondence by generating a signature 293 on any data and then verifying the signature using the returned 294 certificate. The router SHOULD inform the operator whether it 295 successfully received the certificate and whether or not the keys 296 correspond; the mechanism is out of scope. 298 The router SHOULD also verify that the returned certificate validates 299 back to the installed TA Certificate, i.e., the entire chain from the 300 installed TA Certificate through subordinate CAs to the BGPsec 301 certificate validate. To perform this verification the CA 302 certificate chain needs to be returned along with the router's 303 certificate in the PKCS#7 certs-only message. The router SHOULD 304 inform the operator whether or not the signature validates to a trust 305 anchor; this notification mechanism is out of scope. 307 NOTE: The signature on the PKCS#8 and Certificate need not be made by 308 the same entity. Signing the PKCS#8, permits more advanced 309 configurations where the entity that generates the keys is not the 310 direct CA. 312 8. Advanced Deployment Scenarios 314 More PKI-capable routers can take advantage of this increased 315 functionality and lighten the operator's burden. Typically, these 316 routers include either pre-installed manufacturer-generated 317 certificates (e.g., IEEE 802.1 AR [802.1AR]) or pre-installed 318 manufacturer-generated Pre-Shared Keys (PSK) as well as PKI- 319 enrollment functionality and transport protocol, e.g., CMC's "Secure 320 Transport" [RFC7030] or the original CMC transport protocol's 321 [RFC5273]. When the operator first establishes a protected channel 322 between the management system and the router, this pre-installed key 323 material is used to authenticate the router. 325 The operator burden shifts here to include: 327 1. Securely communicating the router's authentication material to 328 the CA prior to operator initiating the router's CSR. CAs use 329 authentication material to determine whether the router is 330 eligible to receive a certificate. Authentication material at a 331 minimum includes the router's AS number and BGP Identifier as 332 well as the router's key material, but can also include 333 additional information. Authentication material can be 334 communicated to the CA (i.e., CSRs signed by this key material 335 are issued certificates with this AS and BGP Identifier) or to 336 the router (i.e., the operator uses the vendor-supplied 337 management interface to include the AS number and BGP Identifier 338 in the router-generated CSR). 340 2. Enabling the router to communicate with the CA. While the 341 router-to-CA communications are operator-initiated, the 342 operator's management interface need not be involved in the 343 communications path. Enabling the router-to-CA connectivity MAY 344 require connections to external networks (i.e., through 345 firewalls, NATs, etc.). 347 Once configured, the operator can begin the process of enrolling the 348 router. Because the router is communicating directly with the CA, 349 there is no need for the operator to retrieve the PKCS#10 350 certification request from the router as in Section 5 or return the 351 PKCS#7 certs-only message to the router as in Section 6. Note that 352 the checks performed by the router in Section 7, namely extracting 353 the certificate from the PKCS#7 certs-only message, verifying the 354 public key corresponds to the private key, and that the returned 355 certificate validated back to an installed trust anchor, SHOULD be 356 performed. Likewise, the router SHOULD notify the operator if any of 357 these fail, but this notification mechanism is out of scope. 359 When a router is so configured the communication with the CA SHOULD 360 be automatically re-established by the router at future times to 361 renew or rekey the certificate automatically when necessary (See 362 Section 8). This further reduces the tasks required of the operator. 364 9. Key Management 366 Key management does not only include key generation, key 367 provisioning, certificate issuance, and certificate distribution. It 368 also includes assurance of key validity, key roll-over, and key 369 preservation during router replacement. All of these 370 responsibilities persist for as long as the operator wishes to 371 operate the BGPsec-speaking router. 373 9.1. Key Validity 375 It is critical that a BGPsec speaking router is signing with a valid 376 private key at all times. To this end, the operator needs to ensure 377 the router always has a non-expired certificate. I.e. the key used 378 to sign BGPsec announcements always has an associated certificate 379 whose expiry time is after the current time. 381 Ensuring this is not terribly difficult but requires that either: 383 1. The router has a mechanism to notify the operator that the 384 certificate has an impending expiration, and/or 386 2. The operator notes the expiry time of the certificate and uses a 387 calendaring program to remind them of the expiry time, and/or 389 3. The RPKI CA warns the operator of pending expiration, and/or 391 4. The operator uses some other kind of automated process to search 392 for and track the expiry times of router certificates. 394 It is advisable that expiration warnings happen well in advance of 395 the actual expiry time. 397 Regardless of the technique used to track router certificate expiry 398 times, it is advisable to notify additional operators in the same 399 organization as the expiry time approaches thereby ensuring that the 400 forgetfulness of one operator does not affect the entire 401 organization. 403 Depending on inter-operator relationship, it may be helpful to notify 404 a peer operator that one or more of their certificates are about to 405 expire. 407 9.2. Key Roll-Over 409 Routers that support multiple private keys also greatly increase the 410 chance that routers can continuously speak BGPsec because the new 411 private key and certificate can be obtained and distributed prior to 412 expiration of the operational key. Obviously, the router needs to 413 know when to start using the new key. Once the new key is being 414 used, having the already distributed certificate ensures continuous 415 operation. 417 More information on how to proceed with a Key Roll-Over is described 418 in [I-D.sidrops-bgpsec-rollover]. 420 9.3. Key Revocation 422 Certain unfortunate circumstances may occur causing a need to revoke 423 a router's BGPsec certificate. When this occurs, the operator needs 424 to use the RPKI CA system to revoke the certificate by placing the 425 router's BGPsec certificate on the Certificate Revocation List (CRL) 426 as well as re-keying the router's certificate. 428 When an active router key is to be revoked, the process of requesting 429 the CA to revoke, the process of the CA actually revoking the 430 router's certificate, and then the process of re-keying/renewing the 431 router's certificate, (possibly distributing a new key and 432 certificate to the router), and distributing the status takes time 433 during which the operator must decide how they wish to maintain 434 continuity of operations, with or without the compromised private 435 key, or whether they wish to bring the router offline to address the 436 compromise. 438 Keeping the router operational and BGPsec-speaking is the ideal goal, 439 but if operational practices do not allow this then reconfiguring the 440 router to disable BGPsec is likely preferred to bringing the router 441 offline. 443 Routers which support more than one private key, where one is 444 operational and other(s) are soon-to-be-operational, facilitate 445 revocation events because the operator can configure the router to 446 make a soon-to-be-operational key operational, request revocation of 447 the compromised key, and then make a next generation soon-to-be- 448 operational key, all hopefully without needing to take offline or 449 reboot the router. For routers which support only one operational 450 key, the operators should create or install the new private key, and 451 then request revocation of the certificate corresponding to the 452 compromised private key. 454 9.4. Router Replacement 456 Currently routers often generate private keys for uses such as SSH, 457 and the private keys may not be seen or off-loaded from the router. 458 While this is good security, it creates difficulties when a routing 459 engine or whole router must be replaced in the field and all software 460 which accesses the router must be updated with the new keys. Also, 461 any network based initial contact with a new routing engine requires 462 trust in the public key presented on first contact. 464 To allow operators to quickly replace routers without requiring 465 update and distribution of the corresponding public keys in the RPKI, 466 routers SHOULD allow the private BGPsec key to inserted via a 467 protected channel, e.g., SSH, NetConf (see [RFC6470]), SNMP. This 468 lets the operator escrow the old private key via the mechanism used 469 for operator-generated keys, see Section 5.2, such that it can be re- 470 inserted into a replacement router. The router MAY allow the private 471 key to be to be off-loaded via the protected channel, but this SHOULD 472 be paired with functionality that sets the key into a permanent non- 473 exportable state to ensure that it is not off-loaded at a future time 474 by unauthorized operations. 476 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 introduces no new 487 security considerations. However, it relies on many others and the 488 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 SSH key management is known, in some cases, to be lax 525 [I-D.ylonen-sshkeybcp]; employees that no longer need access to a 526 routers SHOULD be removed the router to ensure only those authorized 527 have access to a router. 529 Though the CA's certificate is installed on the router and used to 530 verify that the returned certificate is in fact signed by the CA, the 531 revocation status of the CA's certificate is rarely checked as the 532 router may not have global connectivity or CRL-aware software. The 533 operator MUST ensure that the installed CA certificate is valid. 535 11. IANA Considerations 537 This document has no IANA Considerations. 539 12. References 541 12.1. Normative References 543 [I-D.sidrops-bgpsec-rollover] 544 Weis, B, R. Gagliano, and K. Patel, "BGPsec Router 545 Certificate Rollover", draft-ietf-sidrops-bgpsec- 546 rollover (work in progress), December 2017. 548 [I-D.lamps-rfc5751-bis] 549 Schaad, J., Ramsdell, B, S. Turner, 550 "Secure/Multipurpose Internet Mail Extension (S/MIME) 551 Version 4.0", draft-ietf-lamps-rfc5751- 552 bis (work in progress), July 2018. 554 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 555 Requirement Levels", BCP 14, RFC 2119, DOI 556 10.17487/RFC2119, March 1997, . 559 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 560 "Randomness Requirements for Security", BCP 106, RFC 4086, 561 DOI 10.17487/RFC4086, June 2005, . 564 [RFC4253] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) 565 Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253, 566 January 2006, . 568 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 569 Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 570 10.17487/RFC4271, January 2006, . 573 [RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, 574 RFC 5652, DOI 10.17487/RFC5652, September 2009, 575 . 577 [RFC5958] Turner, S., "Asymmetric Key Packages", RFC 5958, DOI 578 10.17487/RFC5958, August 2010, . 581 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in 582 RFC 2119 Key Words", BCP 14, RFC 8174, DOI 583 10.17487/RFC8174, May 2017, . 586 [RFC8208] Turner, S. and O. Borchert, "BGPsec Algorithms, Key 587 Formats, and Signature Formats", RFC 8208, DOI 588 10.17487/RFC8208, September 2017, . 591 [RFC8209] Reynolds, M., Turner, S., and S. Kent, "A Profile for 592 BGPsec Router Certificates, Certificate Revocation Lists, 593 and Certification Requests", RFC 8209, DOI 594 10.17487/RFC8209, September 2017, . 597 [802.1AR] IEEE SA-Standards Board, "IEEE Standard for Local and 598 metropolitan area networks - Secure Device Identity", 599 December 2009, 600 . 603 12.1. Informative References 605 [I-D.ylonen-sshkeybcp] 606 Ylonen, T. and G. Kent, "Managing SSH Keys for Automated 607 Access - Current Recommended Practice", draft-ylonen- 608 sshkeybcp (work in progress), April 2013. 610 [RFC2585] Housley, R. and P. Hoffman, "Internet X.509 Public Key 611 Infrastructure Operational Protocols: FTP and HTTP", 612 RFC 2585, DOI 10.17487/RFC2585, May 1999, 613 . 615 [RFC3766] Orman, H. and P. Hoffman, "Determining Strengths For 616 Public Keys Used For Exchanging Symmetric Keys", BCP 86, 617 RFC 3766, DOI 10.17487/RFC3766, April 2004, 618 . 620 [RFC5273] Schaad, J. and M. Myers, "Certificate Management over CMS 621 (CMC): Transport Protocols", RFC 5273, DOI 622 10.17487/RFC5273, June 2008, . 625 [RFC5480] Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk, 626 "Elliptic Curve Cryptography Subject Public Key 627 Information", RFC 5480, DOI 10.17487/RFC5480, March 2009, 628 . 630 [RFC5647] Igoe, K. and J. Solinas, "AES Galois Counter Mode for the 631 Secure Shell Transport Layer Protocol", RFC 5647, DOI 632 10.17487/RFC5647, August 2009, . 635 [RFC5656] Stebila, D. and J. Green, "Elliptic Curve Algorithm 636 Integration in the Secure Shell Transport Layer", 637 RFC 5656, DOI 10.17487/RFC5656, December 2009, 638 . 640 [RFC5967] Turner, S., "The application/pkcs10 Media Type", RFC 5967, 641 DOI 10.17487/RFC5967, August 2010, . 644 [RFC6187] Igoe, K. and D. Stebila, "X.509v3 Certificates for Secure 645 Shell Authentication", RFC 6187, DOI 10.17487/RFC6187, 646 March 2011, . 648 [RFC6470] Bierman, A., "Network Configuration Protocol (NETCONF) 649 Base Notifications", RFC 6470, DOI 10.17487/RFC6470, 650 February 2012, . 652 [RFC6484] Kent, S., Kong, D., Seo, K., and R. Watro, "Certificate 653 Policy (CP) for the Resource Public Key Infrastructure 654 (RPKI)", BCP 173, RFC 6484, DOI 10.17487/RFC6484, February 655 2012, . 657 [RFC6668] Bider, D. and M. Baushke, "SHA-2 Data Integrity 658 Verification for the Secure Shell (SSH) Transport Layer 659 Protocol", RFC 6668, DOI 10.17487/RFC6668, July 2012, 660 . 662 [RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed., 663 "Enrollment over Secure Transport", RFC 7030, DOI 664 10.17487/RFC7030, October 2013, . 667 [RFC8205] Lepinski, M., Ed., and K. Sriram, Ed., "BGPsec Protocol 668 Specification", RFC 8205, DOI 10.17487/RFC8205, September 669 2017, . 671 [SP800-57] National Institute of Standards and Technology (NIST), 672 Special Publication 800-57: Recommendation for Key 673 Management - Part 1 (Revised), March 2007. 675 Appendix A. Management/Router Channel Security 677 Encryption, integrity, authentication, and key exchange algorithms 678 used by the protected channel SHOULD be of equal or greater strength 679 than the BGPsec keys they protect, which for the algorithm specified 680 in [RFC8208] is 128-bit; see [RFC5480] and by reference [SP800-57] 681 for information about this strength claim as well as [RFC3766] for 682 "how to determine the length of an asymmetric key as a function of a 683 symmetric key strength requirement." In other words, for the 684 encryption algorithm, do not use export grade crypto (40-56 bits of 685 security), do not use Triple DES (112 bits of security). Suggested 686 minimum algorithms would be AES-128: aes128-cbc [RFC4253] and 687 AEAD_AES_128_GCM [RFC5647] for encryption, hmac-sha2-256 [RFC6668] or 688 AESAD_AES_128_GCM [RFC5647] for integrity, ecdsa-sha2-nistp256 689 [RFC5656] for authentication, and ecdh-sha2-nistp256 [RFC5656] for 690 key exchange. 692 Some routers support the use of public key certificates and SSH. The 693 certificates used for the SSH session are different than the 694 certificates used for BGPsec. The certificates used with SSH should 695 also enable a level of security commensurate with BGPsec keys; 696 x509v3-ecdsa-sha2-nistp256 [RFC6187] could be used for 697 authentication. 699 The protected channel must provide confidentiality, authentication, 700 and integrity and replay protection. 702 Appendix B. The n00b Guide to BGPsec Key Management 704 This appendix is informative. It attempts to explain all of the PKI 705 technobabble in plainer language. 707 BGPsec speakers send signed BGPsec updates that are verified by other 708 BGPsec speakers. In PKI parlance, the senders are referred to as 709 signers and the receivers are referred to as relying parties. The 710 signers with which we are concerned here are routers signing BGPsec 711 updates. Signers use private keys to sign and relying parties use 712 the corresponding public keys, in the form of X.509 public key 713 certificates, to verify signatures. The third party involved is the 714 entity that issues the X.509 public key certificate, the 715 Certification Authority (CA). Key management is all about making 716 these key pairs and the certificates, as well as ensuring that the 717 relying parties trust that the certified public keys in fact 718 correspond to the signers' private keys. 720 The specifics of key management greatly depend on the routers as well 721 as management interfaces provided by the routers' vendor. Because of 722 these differences, it is hard to write a definitive "how to," but 723 this guide is intended to arm operators with enough information to 724 ask the right questions. The other aspect that makes this guide 725 informative is that the steps for the do-it-yourself (DIY) approach 726 involve arcane commands while the GUI-based vendor-assisted 727 management console approach will likely hide all of those commands 728 behind some button clicks. Regardless, the operator will end up with 729 a BGPsec-enabled router. Initially, we focus on the DIY approach and 730 then follow up with some information about the GUI-based approach. 732 The first step in the DIY approach is to generate a private key; but 733 in fact what you do is create a key pair; one part, the private key, 734 is kept very private and the other part, the public key, is given out 735 to verify whatever is signed. The two models for how to create the 736 key pair are the subject of this document, but it boils down to 737 either doing it on-router (router-driven) or off-router (operator- 738 driven). 740 If you are generating keys on the router (router-driven), then you 741 will need to access the router. Again, how you access the router is 742 router-specific, but generally the DIY approach uses the CLI and 743 accessing the router either directly via the router's craft port or 744 over the network on an administrative interface. If accessing the 745 router over the network be sure to do it securely (i.e., use SSHv2). 746 Once logged into the router, issue a command or a series of commands 747 that will generate the key pair for the algorithms referenced in the 748 main body of this document; consult your router's documentation for 749 the specific commands. The key generation process will yield 750 multiple files: the private key and the public key; the file format 751 varies depending on the arcane command you issued, but generally the 752 files are DER or PEM-encoded. 754 The second step is to generate the certification request, which is 755 often referred to as a certificate signing request (CSR) or PKCS#10 756 certification request, and to send it to the CA to be signed. To 757 generate the CSR, you issue some more arcane commands while logged 758 into the router; using the private key just generated to sign the 759 certification request with the algorithms referenced in the main body 760 of this document; the CSR is signed to prove to the CA that the 761 router has possession of the private key (i.e., the signature is the 762 proof-of-possession). The output of the command is the CSR file; the 763 file format varies depending on the arcane command you issued, but 764 generally the files are DER or PEM-encoded. 766 The third step is to retrieve the signed CSR from the router and send 767 it to the CA. But before sending it, you need to also send the CA 768 the subject name and serial number for the router. The CA needs this 769 information to issue the certificate. How you get the CSR to the CA, 770 is beyond the scope of this document. While you are still connected 771 to the router, install the Trust Anchor (TA) for the root of the PKI. 772 At this point, you no longer need access to the router for BGPsec- 773 related initiation purposes. 775 The fourth step is for the CA to issue the certificate based on the 776 CSR you sent; the certificate will include the subject name, serial 777 number, public key, and other fields as well as being signed by the 778 CA. After the CA issues the certificate, the CA returns the 779 certificate, and posts the certificate to the RPKI repository. Check 780 that the certificate corresponds to the private key by verifying the 781 signature on the CSR sent to the CA; this is just a check to make 782 sure that the CA issued a certificate that includes a public key that 783 is the pair of the private key (i.e., the math will work when 784 verifying a signature generated by the private with the returned 785 certificate). 787 If generating the keys off-router (operator-driven), then the same 788 steps are used as the on-router key generation, (possibly with the 789 same arcane commands as those used in the on-router approach), but no 790 access to the router is needed the first three steps are done on an 791 administrative workstation: o Step 1: Generate key pair; o Step 2: 792 Create CSR and sign CSR with private key, and; o Step 3: Send CSR 793 file with the subject name and serial number to CA. 795 After the CA has returned the certificate and you have checked the 796 certificate, you need to put the private key and TA in the router. 797 Assuming the DIY approach, you will be using the CLI and accessing 798 the router either directly via the router's craft port or over the 799 network on an admin interface; if accessing the router over the 800 network make doubly sure it is done securely (i.e., use SSHv2) 801 because the private key is being moved over the network. At this 802 point, access to the router is no longer needed for BGPsec-related 803 initiation purposes. 805 NOTE: Regardless of the approach taken, the first three steps could 806 trivially be collapsed by a vendor-provided script to yield the 807 private key and the signed CSR. 809 Given a GUI-based vendor-assisted management console, then all of 810 these steps will likely be hidden behind pointing and clicking the 811 way through BGPsec-enabling the router. 813 The scenarios described above require the operator to access each 814 router, which does not scale well to large networks. An alternative 815 would be to create an image, perform the necessary steps to get the 816 private key and trust anchor on the image, and then install the image 817 via a management protocol. 819 One final word of advice; certificates include a notAfter field that 820 unsurprisingly indicates when relying parties should no longer trust 821 the certificate. To avoid having routers with expired certificates 822 follow the recommendations in the Certification Policy (CP) [RFC6484] 823 and make sure to renew the certificate at least one week prior to the 824 notAfter date. Set a calendar reminder in order not to forget! 826 Authors' Addresses 828 Randy Bush 829 IIJ / Dragon Research Labs 830 5147 Crystal Springs 831 Bainbridge Island, Washington 98110 832 US 834 Email: randy@psg.com 836 Sean Turner 837 sn3rd 839 Email: sean@sn3rd.com 841 Keyur Patel 842 Arrcus, Inc. 844 Email: keyur@arrcus.com