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'HKDF') == Outdated reference: draft-ietf-quic-transport has been published as RFC 9000 == Outdated reference: draft-ietf-tls-iana-registry-updates has been published as RFC 8447 == Outdated reference: draft-ietf-tls-tls13 has been published as RFC 8446 == Outdated reference: A later version (-34) exists of draft-ietf-quic-http-11 == Outdated reference: draft-ietf-quic-recovery has been published as RFC 9002 Summary: 2 errors (**), 0 flaws (~~), 7 warnings (==), 6 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 QUIC M. Thomson, Ed. 3 Internet-Draft Mozilla 4 Intended status: Standards Track S. Turner, Ed. 5 Expires: October 19, 2018 sn3rd 6 April 17, 2018 8 Using Transport Layer Security (TLS) to Secure QUIC 9 draft-ietf-quic-tls-11 11 Abstract 13 This document describes how Transport Layer Security (TLS) is used to 14 secure QUIC. 16 Note to Readers 18 Discussion of this draft takes place on the QUIC working group 19 mailing list (quic@ietf.org), which is archived at 20 https://mailarchive.ietf.org/arch/search/?email_list=quic [1]. 22 Working Group information can be found at https://github.com/quicwg 23 [2]; source code and issues list for this draft can be found at 24 https://github.com/quicwg/base-drafts/labels/-tls [3]. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at https://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on October 19, 2018. 43 Copyright Notice 45 Copyright (c) 2018 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (https://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 61 2. Notational Conventions . . . . . . . . . . . . . . . . . . . 4 62 3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 4 63 3.1. TLS Overview . . . . . . . . . . . . . . . . . . . . . . 5 64 3.2. TLS Handshake . . . . . . . . . . . . . . . . . . . . . . 6 65 4. TLS Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 7 66 4.1. Handshake and Setup Sequence . . . . . . . . . . . . . . 8 67 4.2. Interface to TLS . . . . . . . . . . . . . . . . . . . . 9 68 4.2.1. Handshake Interface . . . . . . . . . . . . . . . . . 10 69 4.2.2. Source Address Validation . . . . . . . . . . . . . . 11 70 4.2.3. Key Ready Events . . . . . . . . . . . . . . . . . . 12 71 4.2.4. Secret Export . . . . . . . . . . . . . . . . . . . . 12 72 4.2.5. TLS Interface Summary . . . . . . . . . . . . . . . . 12 73 4.3. TLS Version . . . . . . . . . . . . . . . . . . . . . . . 13 74 4.4. ClientHello Size . . . . . . . . . . . . . . . . . . . . 13 75 4.5. Peer Authentication . . . . . . . . . . . . . . . . . . . 14 76 4.6. Rejecting 0-RTT . . . . . . . . . . . . . . . . . . . . . 14 77 4.7. TLS Errors . . . . . . . . . . . . . . . . . . . . . . . 15 78 5. QUIC Packet Protection . . . . . . . . . . . . . . . . . . . 15 79 5.1. Installing New Keys . . . . . . . . . . . . . . . . . . . 15 80 5.2. Enabling 0-RTT . . . . . . . . . . . . . . . . . . . . . 15 81 5.3. QUIC Key Expansion . . . . . . . . . . . . . . . . . . . 16 82 5.3.1. QHKDF-Expand . . . . . . . . . . . . . . . . . . . . 16 83 5.3.2. Handshake Secrets . . . . . . . . . . . . . . . . . . 17 84 5.3.3. 0-RTT Secret . . . . . . . . . . . . . . . . . . . . 17 85 5.3.4. 1-RTT Secrets . . . . . . . . . . . . . . . . . . . . 18 86 5.3.5. Updating 1-RTT Secrets . . . . . . . . . . . . . . . 18 87 5.3.6. Packet Protection Keys . . . . . . . . . . . . . . . 18 88 5.4. QUIC AEAD Usage . . . . . . . . . . . . . . . . . . . . . 19 89 5.5. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 20 90 5.6. Receiving Protected Packets . . . . . . . . . . . . . . . 21 91 5.7. Packet Number Gaps . . . . . . . . . . . . . . . . . . . 21 92 6. Key Phases . . . . . . . . . . . . . . . . . . . . . . . . . 21 93 6.1. Packet Protection for the TLS Handshake . . . . . . . . . 22 94 6.1.1. Initial Key Transitions . . . . . . . . . . . . . . . 22 95 6.1.2. Retransmission and Acknowledgment of Unprotected 96 Packets . . . . . . . . . . . . . . . . . . . . . . . 23 97 6.2. Key Update . . . . . . . . . . . . . . . . . . . . . . . 24 98 7. Client Address Validation . . . . . . . . . . . . . . . . . . 25 99 7.1. HelloRetryRequest Address Validation . . . . . . . . . . 26 100 7.1.1. Stateless Address Validation . . . . . . . . . . . . 26 101 7.1.2. Sending HelloRetryRequest . . . . . . . . . . . . . . 27 102 7.2. NewSessionTicket Address Validation . . . . . . . . . . . 27 103 7.3. Address Validation Token Integrity . . . . . . . . . . . 28 104 8. Pre-handshake QUIC Messages . . . . . . . . . . . . . . . . . 28 105 8.1. Unprotected Packets Prior to Handshake Completion . . . . 29 106 8.1.1. STREAM Frames . . . . . . . . . . . . . . . . . . . . 29 107 8.1.2. ACK Frames . . . . . . . . . . . . . . . . . . . . . 29 108 8.1.3. Updates to Data and Stream Limits . . . . . . . . . . 30 109 8.1.4. Handshake Failures . . . . . . . . . . . . . . . . . 31 110 8.1.5. Address Verification . . . . . . . . . . . . . . . . 31 111 8.1.6. Denial of Service with Unprotected Packets . . . . . 31 112 8.2. Use of 0-RTT Keys . . . . . . . . . . . . . . . . . . . . 32 113 8.3. Receiving Out-of-Order Protected Frames . . . . . . . . . 32 114 9. QUIC-Specific Additions to the TLS Handshake . . . . . . . . 33 115 9.1. Protocol and Version Negotiation . . . . . . . . . . . . 33 116 9.2. QUIC Transport Parameters Extension . . . . . . . . . . . 33 117 10. Security Considerations . . . . . . . . . . . . . . . . . . . 34 118 10.1. Packet Reflection Attack Mitigation . . . . . . . . . . 34 119 10.2. Peer Denial of Service . . . . . . . . . . . . . . . . . 34 120 11. Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . 35 121 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35 122 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 36 123 13.1. Normative References . . . . . . . . . . . . . . . . . . 36 124 13.2. Informative References . . . . . . . . . . . . . . . . . 37 125 13.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 38 126 Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 38 127 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 38 128 Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 38 129 C.1. Since draft-ietf-quic-tls-10 . . . . . . . . . . . . . . 38 130 C.2. Since draft-ietf-quic-tls-09 . . . . . . . . . . . . . . 38 131 C.3. Since draft-ietf-quic-tls-08 . . . . . . . . . . . . . . 38 132 C.4. Since draft-ietf-quic-tls-07 . . . . . . . . . . . . . . 38 133 C.5. Since draft-ietf-quic-tls-05 . . . . . . . . . . . . . . 39 134 C.6. Since draft-ietf-quic-tls-04 . . . . . . . . . . . . . . 39 135 C.7. Since draft-ietf-quic-tls-03 . . . . . . . . . . . . . . 39 136 C.8. Since draft-ietf-quic-tls-02 . . . . . . . . . . . . . . 39 137 C.9. Since draft-ietf-quic-tls-01 . . . . . . . . . . . . . . 39 138 C.10. Since draft-ietf-quic-tls-00 . . . . . . . . . . . . . . 39 139 C.11. Since draft-thomson-quic-tls-01 . . . . . . . . . . . . . 40 140 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40 142 1. Introduction 144 This document describes how QUIC [QUIC-TRANSPORT] is secured using 145 Transport Layer Security (TLS) version 1.3 [TLS13]. TLS 1.3 provides 146 critical latency improvements for connection establishment over 147 previous versions. Absent packet loss, most new connections can be 148 established and secured within a single round trip; on subsequent 149 connections between the same client and server, the client can often 150 send application data immediately, that is, using a zero round trip 151 setup. 153 This document describes how the standardized TLS 1.3 acts a security 154 component of QUIC. The same design could work for TLS 1.2, though 155 few of the benefits QUIC provides would be realized due to the 156 handshake latency in versions of TLS prior to 1.3. 158 2. Notational Conventions 160 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 161 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 162 "OPTIONAL" in this document are to be interpreted as described in BCP 163 14 [RFC2119] [RFC8174] when, and only when, they appear in all 164 capitals, as shown here. 166 This document uses the terminology established in [QUIC-TRANSPORT]. 168 For brevity, the acronym TLS is used to refer to TLS 1.3. 170 TLS terminology is used when referring to parts of TLS. Though TLS 171 assumes a continuous stream of octets, it divides that stream into 172 _records_. Most relevant to QUIC are the records that contain TLS 173 _handshake messages_, which are discrete messages that are used for 174 key agreement, authentication and parameter negotiation. Ordinarily, 175 TLS records can also contain _application data_, though in the QUIC 176 usage there is no use of TLS application data. 178 3. Protocol Overview 180 QUIC [QUIC-TRANSPORT] assumes responsibility for the confidentiality 181 and integrity protection of packets. For this it uses keys derived 182 from a TLS 1.3 connection [TLS13]; QUIC also relies on TLS 1.3 for 183 authentication and negotiation of parameters that are critical to 184 security and performance. 186 Rather than a strict layering, these two protocols are co-dependent: 187 QUIC uses the TLS handshake; TLS uses the reliability and ordered 188 delivery provided by QUIC streams. 190 This document defines how QUIC interacts with TLS. This includes a 191 description of how TLS is used, how keying material is derived from 192 TLS, and the application of that keying material to protect QUIC 193 packets. Figure 1 shows the basic interactions between TLS and QUIC, 194 with the QUIC packet protection being called out specially. 196 +------------+ +------------+ 197 | |------ Handshake ------>| | 198 | |<-- Validate Address ---| | 199 | |-- OK/Error/Validate -->| | 200 | |<----- Handshake -------| | 201 | QUIC |------ Validate ------->| TLS | 202 | | | | 203 | |<------ 0-RTT OK -------| | 204 | |<------ 1-RTT OK -------| | 205 | |<--- Handshake Done ----| | 206 +------------+ +------------+ 207 | ^ ^ | 208 | Protect | Protected | | 209 v | Packet | | 210 +------------+ / / 211 | QUIC | / / 212 | Packet |-------- Get Secret -------' / 213 | Protection |<-------- Secret -----------' 214 +------------+ 216 Figure 1: QUIC and TLS Interactions 218 The initial state of a QUIC connection has packets exchanged without 219 any form of protection. In this state, QUIC is limited to using 220 stream 0 and associated packets. Stream 0 is reserved for a TLS 221 connection. This is a complete TLS connection as it would appear 222 when layered over TCP; the only difference is that QUIC provides the 223 reliability and ordering that would otherwise be provided by TCP. 225 At certain points during the TLS handshake, keying material is 226 exported from the TLS connection for use by QUIC. This keying 227 material is used to derive packet protection keys. Details on how 228 and when keys are derived and used are included in Section 5. 230 3.1. TLS Overview 232 TLS provides two endpoints with a way to establish a means of 233 communication over an untrusted medium (that is, the Internet) that 234 ensures that messages they exchange cannot be observed, modified, or 235 forged. 237 TLS features can be separated into two basic functions: an 238 authenticated key exchange and record protection. QUIC primarily 239 uses the authenticated key exchange provided by TLS but provides its 240 own packet protection. 242 The TLS authenticated key exchange occurs between two entities: 243 client and server. The client initiates the exchange and the server 244 responds. If the key exchange completes successfully, both client 245 and server will agree on a secret. TLS supports both pre-shared key 246 (PSK) and Diffie-Hellman (DH) key exchanges. PSK is the basis for 247 0-RTT; the latter provides perfect forward secrecy (PFS) when the DH 248 keys are destroyed. 250 After completing the TLS handshake, the client will have learned and 251 authenticated an identity for the server and the server is optionally 252 able to learn and authenticate an identity for the client. TLS 253 supports X.509 [RFC5280] certificate-based authentication for both 254 server and client. 256 The TLS key exchange is resistent to tampering by attackers and it 257 produces shared secrets that cannot be controlled by either 258 participating peer. 260 3.2. TLS Handshake 262 TLS 1.3 provides two basic handshake modes of interest to QUIC: 264 o A full 1-RTT handshake in which the client is able to send 265 application data after one round trip and the server immediately 266 responds after receiving the first handshake message from the 267 client. 269 o A 0-RTT handshake in which the client uses information it has 270 previously learned about the server to send application data 271 immediately. This application data can be replayed by an attacker 272 so it MUST NOT carry a self-contained trigger for any non- 273 idempotent action. 275 A simplified TLS 1.3 handshake with 0-RTT application data is shown 276 in Figure 2, see [TLS13] for more options and details. 278 Client Server 280 ClientHello 281 (0-RTT Application Data) --------> 282 ServerHello 283 {EncryptedExtensions} 284 {Finished} 285 <-------- [Application Data] 286 (EndOfEarlyData) 287 {Finished} --------> 289 [Application Data] <-------> [Application Data] 291 Figure 2: TLS Handshake with 0-RTT 293 This 0-RTT handshake is only possible if the client and server have 294 previously communicated. In the 1-RTT handshake, the client is 295 unable to send protected application data until it has received all 296 of the handshake messages sent by the server. 298 Two additional variations on this basic handshake exchange are 299 relevant to this document: 301 o The server can respond to a ClientHello with a HelloRetryRequest, 302 which adds an additional round trip prior to the basic exchange. 303 This is needed if the server wishes to request a different key 304 exchange key from the client. HelloRetryRequest is also used to 305 verify that the client is correctly able to receive packets on the 306 address it claims to have (see [QUIC-TRANSPORT]). 308 o A pre-shared key mode can be used for subsequent handshakes to 309 reduce the number of public key operations. This is the basis for 310 0-RTT data, even if the remainder of the connection is protected 311 by a new Diffie-Hellman exchange. 313 4. TLS Usage 315 QUIC reserves stream 0 for a TLS connection. Stream 0 contains a 316 complete TLS connection, which includes the TLS record layer. Other 317 than the definition of a QUIC-specific extension (see Section 9.2), 318 TLS is unmodified for this use. This means that TLS will apply 319 confidentiality and integrity protection to its records. In 320 particular, TLS record protection is what provides confidentiality 321 protection for the TLS handshake messages sent by the server. 323 QUIC permits a client to send frames on streams starting from the 324 first packet. The initial packet from a client contains a stream 325 frame for stream 0 that contains the first TLS handshake messages 326 from the client. This allows the TLS handshake to start with the 327 first packet that a client sends. 329 QUIC packets are protected using a scheme that is specific to QUIC, 330 see Section 5. Keys are exported from the TLS connection when they 331 become available using a TLS exporter (see Section 7.5 of [TLS13] and 332 Section 5.3). After keys are exported from TLS, QUIC manages its own 333 key schedule. 335 4.1. Handshake and Setup Sequence 337 The integration of QUIC with a TLS handshake is shown in more detail 338 in Figure 3. QUIC "STREAM" frames on stream 0 carry the TLS 339 handshake. QUIC performs loss recovery [QUIC-RECOVERY] for this 340 stream and ensures that TLS handshake messages are delivered in the 341 correct order. 343 Client Server 345 @H QUIC STREAM Frame(s) <0>: 346 ClientHello 347 + QUIC Extension 348 --------> 349 0-RTT Key => @0 351 @0 QUIC STREAM Frame(s) : 352 Replayable QUIC Frames 353 --------> 355 QUIC STREAM Frame <0>: @H 356 ServerHello 357 {TLS Handshake Messages} 358 <-------- 359 1-RTT Key => @1 361 QUIC Frames @1 362 <-------- 363 @H QUIC STREAM Frame(s) <0>: 364 (EndOfEarlyData) 365 {Finished} 366 --------> 368 @1 QUIC Frames <-------> QUIC Frames @1 370 Figure 3: QUIC over TLS Handshake 372 In Figure 3, symbols mean: 374 o "<" and ">" enclose stream numbers. 376 o "@" indicates the keys that are used for protecting the QUIC 377 packet (H = handshake, using keys from the well-known cleartext 378 packet secret; 0 = 0-RTT keys; 1 = 1-RTT keys). 380 o "(" and ")" enclose messages that are protected with TLS 0-RTT 381 handshake or application keys. 383 o "{" and "}" enclose messages that are protected by the TLS 384 Handshake keys. 386 If 0-RTT is not attempted, then the client does not send packets 387 protected by the 0-RTT key (@0). In that case, the only key 388 transition on the client is from handshake packets (@H) to 1-RTT 389 protection (@1), which happens after it sends its final set of TLS 390 handshake messages. 392 Note: two different types of packet are used during the handshake by 393 both client and server. The Initial packet carries a TLS ClientHello 394 message; the remainder of the TLS handshake is carried in Handshake 395 packets. The Retry packet carries a TLS HelloRetryRequest, if it is 396 needed, and Handshake packets carry the remainder of the server 397 handshake. 399 The server sends TLS handshake messages without protection (@H). The 400 server transitions from no protection (@H) to full 1-RTT protection 401 (@1) after it sends the last of its handshake messages. 403 Some TLS handshake messages are protected by the TLS handshake record 404 protection. These keys are not exported from the TLS connection for 405 use in QUIC. QUIC packets from the server are sent in the clear 406 until the final transition to 1-RTT keys. 408 The client transitions from handshake (@H) to 0-RTT keys (@0) when 409 sending 0-RTT data, and subsequently to to 1-RTT keys (@1) after its 410 second flight of TLS handshake messages. This creates the potential 411 for unprotected packets to be received by a server in close proximity 412 to packets that are protected with 1-RTT keys. 414 More information on key transitions is included in Section 6.1. 416 4.2. Interface to TLS 418 As shown in Figure 1, the interface from QUIC to TLS consists of four 419 primary functions: Handshake, Source Address Validation, Key Ready 420 Events, and Secret Export. 422 Additional functions might be needed to configure TLS. 424 4.2.1. Handshake Interface 426 In order to drive the handshake, TLS depends on being able to send 427 and receive handshake messages on stream 0. There are two basic 428 functions on this interface: one where QUIC requests handshake 429 messages and one where QUIC provides handshake packets. 431 Before starting the handshake QUIC provides TLS with the transport 432 parameters (see Section 9.2) that it wishes to carry. 434 A QUIC client starts TLS by requesting TLS handshake octets from TLS. 435 The client acquires handshake octets before sending its first packet. 437 A QUIC server starts the process by providing TLS with stream 0 438 octets. 440 Each time that an endpoint receives data on stream 0, it delivers the 441 octets to TLS if it is able. Each time that TLS is provided with new 442 data, new handshake octets are requested from TLS. TLS might not 443 provide any octets if the handshake messages it has received are 444 incomplete or it has no data to send. 446 At the server, when TLS provides handshake octets, it also needs to 447 indicate whether the octets contain a HelloRetryRequest. A 448 HelloRetryRequest MUST always be sent in a Retry packet, so the QUIC 449 server needs to know whether the octets are a HelloRetryRequest. 451 Once the TLS handshake is complete, this is indicated to QUIC along 452 with any final handshake octets that TLS needs to send. TLS also 453 provides QUIC with the transport parameters that the peer advertised 454 during the handshake. 456 Once the handshake is complete, TLS becomes passive. TLS can still 457 receive data from its peer and respond in kind, but it will not need 458 to send more data unless specifically requested - either by an 459 application or QUIC. One reason to send data is that the server 460 might wish to provide additional or updated session tickets to a 461 client. 463 When the handshake is complete, QUIC only needs to provide TLS with 464 any data that arrives on stream 0. In the same way that is done 465 during the handshake, new data is requested from TLS after providing 466 received data. 468 Important: Until the handshake is reported as complete, the 469 connection and key exchange are not properly authenticated at the 470 server. Even though 1-RTT keys are available to a server after 471 receiving the first handshake messages from a client, the server 472 cannot consider the client to be authenticated until it receives 473 and validates the client's Finished message. 475 The requirement for the server to wait for the client Finished 476 message creates a dependency on that message being delivered. A 477 client can avoid the potential for head-of-line blocking that this 478 implies by sending a copy of the STREAM frame that carries the 479 Finished message in multiple packets. This enables immediate 480 server processing for those packets. 482 4.2.2. Source Address Validation 484 During the processing of the TLS ClientHello, TLS requests that the 485 transport make a decision about whether to request source address 486 validation from the client. 488 An initial TLS ClientHello that resumes a session includes an address 489 validation token in the session ticket; this includes all attempts at 490 0-RTT. If the client does not attempt session resumption, no token 491 will be present. While processing the initial ClientHello, TLS 492 provides QUIC with any token that is present. In response, QUIC 493 provides one of three responses: 495 o proceed with the connection, 497 o ask for client address validation, or 499 o abort the connection. 501 If QUIC requests source address validation, it also provides a new 502 address validation token. TLS includes that along with any 503 information it requires in the cookie extension of a TLS 504 HelloRetryRequest message. In the other cases, the connection either 505 proceeds or terminates with a handshake error. 507 The client echoes the cookie extension in a second ClientHello. A 508 ClientHello that contains a valid cookie extension will always be in 509 response to a HelloRetryRequest. If address validation was requested 510 by QUIC, then this will include an address validation token. TLS 511 makes a second address validation request of QUIC, including the 512 value extracted from the cookie extension. In response to this 513 request, QUIC cannot ask for client address validation, it can only 514 abort or permit the connection attempt to proceed. 516 QUIC can provide a new address validation token for use in session 517 resumption at any time after the handshake is complete. Each time a 518 new token is provided TLS generates a NewSessionTicket message, with 519 the token included in the ticket. 521 See Section 7 for more details on client address validation. 523 4.2.3. Key Ready Events 525 TLS provides QUIC with signals when 0-RTT and 1-RTT keys are ready 526 for use. These events are not asynchronous, they always occur 527 immediately after TLS is provided with new handshake octets, or after 528 TLS produces handshake octets. 530 When TLS completed its handshake, 1-RTT keys can be provided to QUIC. 531 On both client and server, this occurs after sending the TLS Finished 532 message. 534 This ordering means that there could be frames that carry TLS 535 handshake messages ready to send at the same time that application 536 data is available. An implementation MUST ensure that TLS handshake 537 messages are always sent in packets protected with handshake keys 538 (see Section 5.3.2). Separate packets are required for data that 539 needs protection from 1-RTT keys. 541 If 0-RTT is possible, it is ready after the client sends a TLS 542 ClientHello message or the server receives that message. After 543 providing a QUIC client with the first handshake octets, the TLS 544 stack might signal that 0-RTT keys are ready. On the server, after 545 receiving handshake octets that contain a ClientHello message, a TLS 546 server might signal that 0-RTT keys are available. 548 1-RTT keys are used for packets in both directions. 0-RTT keys are 549 only used to protect packets sent by the client. 551 4.2.4. Secret Export 553 Details how secrets are exported from TLS are included in 554 Section 5.3. 556 4.2.5. TLS Interface Summary 558 Figure 4 summarizes the exchange between QUIC and TLS for both client 559 and server. 561 Client Server 563 Get Handshake 564 0-RTT Key Ready 565 --- send/receive ---> 566 Handshake Received 567 0-RTT Key Ready 568 Get Handshake 569 1-RTT Keys Ready 570 <--- send/receive --- 571 Handshake Received 572 Get Handshake 573 Handshake Complete 574 1-RTT Keys Ready 575 --- send/receive ---> 576 Handshake Received 577 Get Handshake 578 Handshake Complete 579 <--- send/receive --- 580 Handshake Received 581 Get Handshake 583 Figure 4: Interaction Summary between QUIC and TLS 585 4.3. TLS Version 587 This document describes how TLS 1.3 [TLS13] is used with QUIC. 589 In practice, the TLS handshake will negotiate a version of TLS to 590 use. This could result in a newer version of TLS than 1.3 being 591 negotiated if both endpoints support that version. This is 592 acceptable provided that the features of TLS 1.3 that are used by 593 QUIC are supported by the newer version. 595 A badly configured TLS implementation could negotiate TLS 1.2 or 596 another older version of TLS. An endpoint MUST terminate the 597 connection if a version of TLS older than 1.3 is negotiated. 599 4.4. ClientHello Size 601 QUIC requires that the initial handshake packet from a client fit 602 within the payload of a single packet. The size limits on QUIC 603 packets mean that a record containing a ClientHello needs to fit 604 within 1129 octets, though endpoints can reduce the size of their 605 connection ID to increase by up to 22 octets. 607 A TLS ClientHello can fit within this limit with ample space 608 remaining. However, there are several variables that could cause 609 this limit to be exceeded. Implementations are reminded that large 610 session tickets or HelloRetryRequest cookies, multiple or large key 611 shares, and long lists of supported ciphers, signature algorithms, 612 versions, QUIC transport parameters, and other negotiable parameters 613 and extensions could cause this message to grow. 615 For servers, the size of the session tickets and HelloRetryRequest 616 cookie extension can have an effect on a client's ability to connect. 617 Choosing a small value increases the probability that these values 618 can be successfully used by a client. 620 The TLS implementation does not need to ensure that the ClientHello 621 is sufficiently large. QUIC PADDING frames are added to increase the 622 size of the packet as necessary. 624 4.5. Peer Authentication 626 The requirements for authentication depend on the application 627 protocol that is in use. TLS provides server authentication and 628 permits the server to request client authentication. 630 A client MUST authenticate the identity of the server. This 631 typically involves verification that the identity of the server is 632 included in a certificate and that the certificate is issued by a 633 trusted entity (see for example [RFC2818]). 635 A server MAY request that the client authenticate during the 636 handshake. A server MAY refuse a connection if the client is unable 637 to authenticate when requested. The requirements for client 638 authentication vary based on application protocol and deployment. 640 A server MUST NOT use post-handshake client authentication (see 641 Section 4.6.2 of [TLS13]). 643 4.6. Rejecting 0-RTT 645 A server rejects 0-RTT by rejecting 0-RTT at the TLS layer. This 646 results in early exporter keys being unavailable, thereby preventing 647 the use of 0-RTT for QUIC. 649 A client that attempts 0-RTT MUST also consider 0-RTT to be rejected 650 if it receives a Retry or Version Negotiation packet. 652 When 0-RTT is rejected, all connection characteristics that the 653 client assumed might be incorrect. This includes the choice of 654 application protocol, transport parameters, and any application 655 configuration. The client therefore MUST reset the state of all 656 streams, including application state bound to those streams. 658 4.7. TLS Errors 660 Errors in the TLS connection SHOULD be signaled using TLS alerts on 661 stream 0. A failure in the handshake MUST be treated as a QUIC 662 connection error of type TLS_HANDSHAKE_FAILED. Once the handshake is 663 complete, an error in the TLS connection that causes a TLS alert to 664 be sent or received MUST be treated as a QUIC connection error of 665 type TLS_FATAL_ALERT_GENERATED or TLS_FATAL_ALERT_RECEIVED 666 respectively. 668 5. QUIC Packet Protection 670 QUIC packet protection provides authenticated encryption of packets. 671 This provides confidentiality and integrity protection for the 672 content of packets (see Section 5.4). Packet protection uses keys 673 that are exported from the TLS connection (see Section 5.3). 675 Different keys are used for QUIC packet protection and TLS record 676 protection. TLS handshake messages are protected solely with TLS 677 record protection, but post-handshake messages are redundantly 678 protected with both the QUIC packet protection and the TLS record 679 protection. These messages are limited in number, and so the 680 additional overhead is small. 682 5.1. Installing New Keys 684 As TLS reports the availability of keying material, the packet 685 protection keys and initialization vectors (IVs) are updated (see 686 Section 5.3). The selection of AEAD function is also updated to 687 match the AEAD negotiated by TLS. 689 For packets other than any handshake packets (see Section 6.1), once 690 a change of keys has been made, packets with higher packet numbers 691 MUST be sent with the new keying material. The KEY_PHASE bit on 692 these packets is inverted each time new keys are installed to signal 693 the use of the new keys to the recipient (see Section 6 for details). 695 An endpoint retransmits stream data in a new packet. New packets 696 have new packet numbers and use the latest packet protection keys. 697 This simplifies key management when there are key updates (see 698 Section 6.2). 700 5.2. Enabling 0-RTT 702 In order to be usable for 0-RTT, TLS MUST provide a NewSessionTicket 703 message that contains the "max_early_data" extension with the value 704 0xffffffff; the amount of data which the client can send in 0-RTT is 705 controlled by the "initial_max_data" transport parameter supplied by 706 the server. A client MUST treat receipt of a NewSessionTicket that 707 contains a "max_early_data" extension with any other value as a 708 connection error of type PROTOCOL_VIOLATION. 710 Early data within the TLS connection MUST NOT be used. As it is for 711 other TLS application data, a server MUST treat receiving early data 712 on the TLS connection as a connection error of type 713 PROTOCOL_VIOLATION. 715 5.3. QUIC Key Expansion 717 QUIC uses a system of packet protection secrets, keys and IVs that 718 are modelled on the system used in TLS [TLS13]. The secrets that 719 QUIC uses as the basis of its key schedule are obtained using TLS 720 exporters (see Section 7.5 of [TLS13]). 722 5.3.1. QHKDF-Expand 724 QUIC uses the Hash-based Key Derivation Function (HKDF) [HKDF] with 725 the same hash function negotiated by TLS for key derivation. For 726 example, if TLS is using the TLS_AES_128_GCM_SHA256, the SHA-256 hash 727 function is used. 729 Most key derivations in this document use the QHKDF-Expand function, 730 which uses the HKDF expand function and is modelled on the HKDF- 731 Expand-Label function from TLS 1.3 (see Section 7.1 of [TLS13]). 732 QHKDF-Expand differs from HKDF-Expand-Label in that it uses a 733 different base label and omits the Context argument. 735 QHKDF-Expand(Secret, Label, Length) = 736 HKDF-Expand(Secret, QhkdfExpandInfo, Length) 738 The HKDF-Expand function used by QHKDF-Expand uses the PRF hash 739 function negotiated by TLS, except for handshake secrets and keys 740 derived from them (see Section 5.3.2). 742 Where the "info" parameter of HKDF-Expand is an encoded 743 "QhkdfExpandInfo" structure: 745 struct { 746 uint16 length = Length; 747 opaque label<6..255> = "QUIC " + Label; 748 } QhkdfExpandInfo; 750 For example, assuming a hash function with a 32 octet output, 751 derivation for a client packet protection key would use HKDF-Expand 752 with an "info" parameter of 0x00200851554943206b6579. 754 5.3.2. Handshake Secrets 756 Packets that carry the TLS handshake (Initial, Retry, and Handshake) 757 are protected with a secret derived from the Destination Connection 758 ID field from the client's Initial packet. Specifically: 760 handshake_salt = 0x9c108f98520a5c5c32968e950e8a2c5fe06d6c38 761 handshake_secret = 762 HKDF-Extract(handshake_salt, client_dst_connection_id) 764 client_handshake_secret = 765 QHKDF-Expand(handshake_secret, "client hs", Hash.length) 766 server_handshake_secret = 767 QHKDF-Expand(handshake_secret, "server hs", Hash.length) 769 The hash function for HKDF when deriving handshake secrets and keys 770 is SHA-256 [FIPS180]. The connection ID used with QHKDF-Expand is 771 the connection ID chosen by the client. 773 The handshake salt is a 20 octet sequence shown in the figure in 774 hexadecimal notation. Future versions of QUIC SHOULD generate a new 775 salt value, thus ensuring that the keys are different for each 776 version of QUIC. This prevents a middlebox that only recognizes one 777 version of QUIC from seeing or modifying the contents of handshake 778 packets from future versions. 780 Note: The Destination Connection ID is of arbitrary length, and it 781 could be zero length if the server sends a Retry packet with a 782 zero-length Source Connection ID field. In this case, the 783 handshake keys provide no assurance to the client that the server 784 received its packet; the client has to rely on the exchange that 785 included the Retry packet for that property. 787 5.3.3. 0-RTT Secret 789 0-RTT keys are those keys that are used in resumed connections prior 790 to the completion of the TLS handshake. Data sent using 0-RTT keys 791 might be replayed and so has some restrictions on its use, see 792 Section 8.2. 0-RTT keys are used after sending or receiving a 793 ClientHello. 795 The secret is exported from TLS using the exporter label "EXPORTER- 796 QUIC 0rtt" and an empty context. The size of the secret MUST be the 797 size of the hash output for the PRF hash function negotiated by TLS. 798 This uses the TLS early_exporter_secret. The QUIC 0-RTT secret is 799 only used for protection of packets sent by the client. 801 client_0rtt_secret = 802 TLS-Early-Exporter("EXPORTER-QUIC 0rtt", "", Hash.length) 804 5.3.4. 1-RTT Secrets 806 1-RTT keys are used by both client and server after the TLS handshake 807 completes. There are two secrets used at any time: one is used to 808 derive packet protection keys for packets sent by the client, the 809 other for packet protection keys on packets sent by the server. 811 The initial client packet protection secret is exported from TLS 812 using the exporter label "EXPORTER-QUIC client 1rtt"; the initial 813 server packet protection secret uses the exporter label "EXPORTER- 814 QUIC server 1rtt". Both exporters use an empty context. The size of 815 the secret MUST be the size of the hash output for the PRF hash 816 function negotiated by TLS. 818 client_pp_secret<0> = 819 TLS-Exporter("EXPORTER-QUIC client 1rtt", "", Hash.length) 820 server_pp_secret<0> = 821 TLS-Exporter("EXPORTER-QUIC server 1rtt", "", Hash.length) 823 These secrets are used to derive the initial client and server packet 824 protection keys. 826 5.3.5. Updating 1-RTT Secrets 828 After a key update (see Section 6.2), the 1-RTT secrets are updated 829 using QHKDF-Expand. Updated secrets are derived from the existing 830 packet protection secret. A Label parameter of "client 1rtt" is used 831 for the client secret and "server 1rtt" for the server. The Length 832 is the same as the native output of the PRF hash function. 834 client_pp_secret = 835 QHKDF-Expand(client_pp_secret, "client 1rtt", Hash.length) 836 server_pp_secret = 837 QHKDF-Expand(server_pp_secret, "server 1rtt", Hash.length) 839 This allows for a succession of new secrets to be created as needed. 841 5.3.6. Packet Protection Keys 843 The complete key expansion uses a similar process for key expansion 844 to that defined in Section 7.3 of [TLS13], using QHKDF-Expand in 845 place of HKDF-Expand-Label. QUIC uses the AEAD function negotiated 846 by TLS. 848 The packet protection key and IV used to protect the 0-RTT packets 849 sent by a client are derived from the QUIC 0-RTT secret. The packet 850 protection keys and IVs for 1-RTT packets sent by the client and 851 server are derived from the current generation of client and server 852 1-RTT secrets (client_pp_secret and server_pp_secret) 853 respectively. 855 The length of the QHKDF-Expand output is determined by the 856 requirements of the AEAD function selected by TLS. The key length is 857 the AEAD key size. As defined in Section 5.3 of [TLS13], the IV 858 length is the larger of 8 or N_MIN (see Section 4 of [AEAD]; all 859 ciphersuites defined in [TLS13] have N_MIN set to 12). 861 For any secret S, the AEAD key uses a label of "key", and the IV uses 862 a label of "iv": 864 key = QHKDF-Expand(S, "key", key_length) 865 iv = QHKDF-Expand(S, "iv", iv_length) 867 Separate keys are derived for packet protection by clients and 868 servers. Each endpoint uses the packet protection key of its peer to 869 remove packet protection. For example, client packet protection keys 870 and IVs - which are also used by the server to remove the protection 871 added by a client - for AEAD_AES_128_GCM are derived from 1-RTT 872 secrets as follows: 874 client_pp_key = QHKDF-Expand(client_pp_secret, "key", 16) 875 client_pp_iv = QHKDF-Expand(client_pp_secret, "iv", 12) 877 The QUIC record protection initially starts with keying material 878 derived from handshake keys. For a client, when the TLS state 879 machine reports that the ClientHello has been sent, 0-RTT keys can be 880 generated and installed for writing, if 0-RTT is available. Finally, 881 the TLS state machine reports completion of the handshake and 1-RTT 882 keys can be generated and installed for writing. 884 5.4. QUIC AEAD Usage 886 The Authentication Encryption with Associated Data (AEAD) [AEAD] 887 function used for QUIC packet protection is AEAD that is negotiated 888 for use with the TLS connection. For example, if TLS is using the 889 TLS_AES_128_GCM_SHA256, the AEAD_AES_128_GCM function is used. 891 All QUIC packets other than Version Negotiation and Stateless Reset 892 packets are protected with an AEAD algorithm [AEAD]. Prior to 893 establishing a shared secret, packets are protected with 894 AEAD_AES_128_GCM and a key derived from the client's connection ID 895 (see Section 5.3.2). This provides protection against off-path 896 attackers and robustness against QUIC version unaware middleboxes, 897 but not against on-path attackers. 899 All ciphersuites currently defined for TLS 1.3 - and therefore QUIC - 900 have a 16-byte authentication tag and produce an output 16 bytes 901 larger than their input. 903 Once TLS has provided a key, the contents of regular QUIC packets 904 immediately after any TLS messages have been sent are protected by 905 the AEAD selected by TLS. 907 The key, K, is either the client packet protection key 908 (client_pp_key) or the server packet protection key 909 (server_pp_key), derived as defined in Section 5.3. 911 The nonce, N, is formed by combining the packet protection IV (either 912 client_pp_iv or server_pp_iv) with the packet number. The 64 913 bits of the reconstructed QUIC packet number in network byte order is 914 left-padded with zeros to the size of the IV. The exclusive OR of 915 the padded packet number and the IV forms the AEAD nonce. 917 The associated data, A, for the AEAD is the contents of the QUIC 918 header, starting from the flags octet in either the short or long 919 header. 921 The input plaintext, P, for the AEAD is the content of the QUIC frame 922 following the header, as described in [QUIC-TRANSPORT]. 924 The output ciphertext, C, of the AEAD is transmitted in place of P. 926 5.5. Packet Numbers 928 QUIC has a single, contiguous packet number space. In comparison, 929 TLS restarts its sequence number each time that record protection 930 keys are changed. The sequence number restart in TLS ensures that a 931 compromise of the current traffic keys does not allow an attacker to 932 truncate the data that is sent after a key update by sending 933 additional packets under the old key (causing new packets to be 934 discarded). 936 QUIC does not assume a reliable transport and is required to handle 937 attacks where packets are dropped in other ways. QUIC is therefore 938 not affected by this form of truncation. 940 The QUIC packet number is not reset and it is not permitted to go 941 higher than its maximum value of 2^62-1. This establishes a hard 942 limit on the number of packets that can be sent. 944 Some AEAD functions have limits for how many packets can be encrypted 945 under the same key and IV (see for example [AEBounds]). This might 946 be lower than the packet number limit. An endpoint MUST initiate a 947 key update (Section 6.2) prior to exceeding any limit set for the 948 AEAD that is in use. 950 TLS maintains a separate sequence number that is used for record 951 protection on the connection that is hosted on stream 0. This 952 sequence number is not visible to QUIC. 954 5.6. Receiving Protected Packets 956 Once an endpoint successfully receives a packet with a given packet 957 number, it MUST discard all packets with higher packet numbers if 958 they cannot be successfully unprotected with either the same key, or 959 - if there is a key update - the next packet protection key (see 960 Section 6.2). Similarly, a packet that appears to trigger a key 961 update, but cannot be unprotected successfully MUST be discarded. 963 Failure to unprotect a packet does not necessarily indicate the 964 existence of a protocol error in a peer or an attack. The truncated 965 packet number encoding used in QUIC can cause packet numbers to be 966 decoded incorrectly if they are delayed significantly. 968 5.7. Packet Number Gaps 970 Section 6.8.5.1 of [QUIC-TRANSPORT] also requires a secret to compute 971 packet number gaps on connection ID transitions. That secret is 972 computed as: 974 packet_number_secret = 975 TLS-Exporter("EXPORTER-QUIC packet number", "", Hash.length) 977 6. Key Phases 979 As TLS reports the availability of 0-RTT and 1-RTT keys, new keying 980 material can be exported from TLS and used for QUIC packet 981 protection. At each transition during the handshake a new secret is 982 exported from TLS and packet protection keys are derived from that 983 secret. 985 Every time that a new set of keys is used for protecting outbound 986 packets, the KEY_PHASE bit in the public flags is toggled. 0-RTT 987 protected packets use the QUIC long header, they do not use the 988 KEY_PHASE bit to select the correct keys (see Section 6.1.1). 990 Once the connection is fully enabled, the KEY_PHASE bit allows a 991 recipient to detect a change in keying material without necessarily 992 needing to receive the first packet that triggered the change. An 993 endpoint that notices a changed KEY_PHASE bit can update keys and 994 decrypt the packet that contains the changed bit, see Section 6.2. 996 The KEY_PHASE bit is included as the 0x20 bit of the QUIC short 997 header. 999 Transitions between keys during the handshake are complicated by the 1000 need to ensure that TLS handshake messages are sent with the correct 1001 packet protection. 1003 6.1. Packet Protection for the TLS Handshake 1005 The initial exchange of packets that carry the TLS handshake are 1006 AEAD-protected using the handshake secrets generated as described in 1007 Section 5.3.2. All TLS handshake messages up to the TLS Finished 1008 message sent by either endpoint use packets protected with handshake 1009 keys. 1011 Any TLS handshake messages that are sent after completing the TLS 1012 handshake do not need special packet protection rules. Packets 1013 containing these messages use the packet protection keys that are 1014 current at the time of sending (or retransmission). 1016 Like the client, a server MUST send retransmissions of its 1017 unprotected handshake messages or acknowledgments for unprotected 1018 handshake messages sent by the client in packets protected with 1019 handshake keys. 1021 6.1.1. Initial Key Transitions 1023 Once the TLS handshake is complete, keying material is exported from 1024 TLS and used to protect QUIC packets. 1026 Packets protected with 1-RTT keys initially have a KEY_PHASE bit set 1027 to 0. This bit inverts with each subsequent key update (see 1028 Section 6.2). 1030 If the client sends 0-RTT data, it uses the 0-RTT packet type. The 1031 packet that contains the TLS EndOfEarlyData and Finished messages are 1032 sent in packets protected with handshake keys. 1034 Using distinct packet types during the handshake for handshake 1035 messages, 0-RTT data, and 1-RTT data ensures that the server is able 1036 to distinguish between the different keys used to remove packet 1037 protection. All of these packets can arrive concurrently at a 1038 server. 1040 A server might choose to retain 0-RTT packets that arrive before a 1041 TLS ClientHello. The server can then use those packets once the 1042 ClientHello arrives. However, the potential for denial of service 1043 from buffering 0-RTT packets is significant. These packets cannot be 1044 authenticated and so might be employed by an attacker to exhaust 1045 server resources. Limiting the number of packets that are saved 1046 might be necessary. 1048 The server transitions to using 1-RTT keys after sending its first 1049 flight of TLS handshake messages, ending in the Finished. From this 1050 point, the server protects all packets with 1-RTT keys. Future 1051 packets are therefore protected with 1-RTT keys. Initially, these 1052 are marked with a KEY_PHASE of 0. 1054 6.1.2. Retransmission and Acknowledgment of Unprotected Packets 1056 TLS handshake messages from both client and server are critical to 1057 the key exchange. The contents of these messages determine the keys 1058 used to protect later messages. If these handshake messages are 1059 included in packets that are protected with these keys, they will be 1060 indecipherable to the recipient. 1062 Even though newer keys could be available when retransmitting, 1063 retransmissions of these handshake messages MUST be sent in packets 1064 protected with handshake keys. An endpoint MUST generate ACK frames 1065 for these messages and send them in packets protected with handshake 1066 keys. 1068 A HelloRetryRequest handshake message might be used to reject an 1069 initial ClientHello. A HelloRetryRequest handshake message is sent 1070 in a Retry packet; any second ClientHello that is sent in response 1071 uses a Initial packet type. These packets are only protected with a 1072 predictable key (see Section 5.3.2). This is natural, because no 1073 shared secret will be available when these messages need to be sent. 1074 Upon receipt of a HelloRetryRequest, a client SHOULD cease any 1075 transmission of 0-RTT data; 0-RTT data will only be discarded by any 1076 server that sends a HelloRetryRequest. 1078 The packet type ensures that protected packets are clearly 1079 distinguished from unprotected packets. Loss or reordering might 1080 cause unprotected packets to arrive once 1-RTT keys are in use, 1081 unprotected packets are easily distinguished from 1-RTT packets using 1082 the packet type. 1084 Once 1-RTT keys are available to an endpoint, it no longer needs the 1085 TLS handshake messages that are carried in unprotected packets. 1086 However, a server might need to retransmit its TLS handshake messages 1087 in response to receiving an unprotected packet that contains ACK 1088 frames. A server MUST process ACK frames in unprotected packets 1089 until the TLS handshake is reported as complete, or it receives an 1090 ACK frame in a protected packet that acknowledges all of its 1091 handshake messages. 1093 To limit the number of key phases that could be active, an endpoint 1094 MUST NOT initiate a key update while there are any unacknowledged 1095 handshake messages, see Section 6.2. 1097 6.2. Key Update 1099 Once the TLS handshake is complete, the KEY_PHASE bit allows for 1100 refreshes of keying material by either peer. Endpoints start using 1101 updated keys immediately without additional signaling; the change in 1102 the KEY_PHASE bit indicates that a new key is in use. 1104 An endpoint MUST NOT initiate more than one key update at a time. A 1105 new key cannot be used until the endpoint has received and 1106 successfully decrypted a packet with a matching KEY_PHASE. Note that 1107 when 0-RTT is attempted the value of the KEY_PHASE bit will be 1108 different on packets sent by either peer. 1110 A receiving endpoint detects an update when the KEY_PHASE bit doesn't 1111 match what it is expecting. It creates a new secret (see 1112 Section 5.3) and the corresponding read key and IV. If the packet 1113 can be decrypted and authenticated using these values, then the keys 1114 it uses for packet protection are also updated. The next packet sent 1115 by the endpoint will then use the new keys. 1117 An endpoint doesn't need to send packets immediately when it detects 1118 that its peer has updated keys. The next packet that it sends will 1119 simply use the new keys. If an endpoint detects a second update 1120 before it has sent any packets with updated keys it indicates that 1121 its peer has updated keys twice without awaiting a reciprocal update. 1122 An endpoint MUST treat consecutive key updates as a fatal error and 1123 abort the connection. 1125 An endpoint SHOULD retain old keys for a short period to allow it to 1126 decrypt packets with smaller packet numbers than the packet that 1127 triggered the key update. This allows an endpoint to consume packets 1128 that are reordered around the transition between keys. Packets with 1129 higher packet numbers always use the updated keys and MUST NOT be 1130 decrypted with old keys. 1132 Keys and their corresponding secrets SHOULD be discarded when an 1133 endpoint has received all packets with packet numbers lower than the 1134 lowest packet number used for the new key. An endpoint might discard 1135 keys if it determines that the length of the delay to affected 1136 packets is excessive. 1138 This ensures that once the handshake is complete, packets with the 1139 same KEY_PHASE will have the same packet protection keys, unless 1140 there are multiple key updates in a short time frame succession and 1141 significant packet reordering. 1143 Initiating Peer Responding Peer 1145 @M QUIC Frames 1146 New Keys -> @N 1147 @N QUIC Frames 1148 --------> 1149 QUIC Frames @M 1150 New Keys -> @N 1151 QUIC Frames @N 1152 <-------- 1154 Figure 5: Key Update 1156 As shown in Figure 3 and Figure 5, there is never a situation where 1157 there are more than two different sets of keying material that might 1158 be received by a peer. Once both sending and receiving keys have 1159 been updated, the peers immediately begin to use them. 1161 A server cannot initiate a key update until it has received the 1162 client's Finished message. Otherwise, packets protected by the 1163 updated keys could be confused for retransmissions of handshake 1164 messages. A client cannot initiate a key update until all of its 1165 handshake messages have been acknowledged by the server. 1167 A packet that triggers a key update could arrive after successfully 1168 processing a packet with a higher packet number. This is only 1169 possible if there is a key compromise and an attack, or if the peer 1170 is incorrectly reverting to use of old keys. Because the latter 1171 cannot be differentiated from an attack, an endpoint MUST immediately 1172 terminate the connection if it detects this condition. 1174 7. Client Address Validation 1176 Two tools are provided by TLS to enable validation of client source 1177 addresses at a server: the cookie in the HelloRetryRequest message, 1178 and the ticket in the NewSessionTicket message. 1180 7.1. HelloRetryRequest Address Validation 1182 The cookie extension in the TLS HelloRetryRequest message allows a 1183 server to perform source address validation during the handshake. 1185 When QUIC requests address validation during the processing of the 1186 first ClientHello, the token it provides is included in the cookie 1187 extension of a HelloRetryRequest. As long as the cookie cannot be 1188 successfully guessed by a client, the server can be assured that the 1189 client received the HelloRetryRequest if it includes the value in a 1190 second ClientHello. 1192 An initial ClientHello never includes a cookie extension. Thus, if a 1193 server constructs a cookie that contains all the information 1194 necessary to reconstruct state, it can discard local state after 1195 sending a HelloRetryRequest. Presence of a valid cookie in a 1196 ClientHello indicates that the ClientHello is a second attempt from 1197 the client. 1199 An address validation token can be extracted from a second 1200 ClientHello and passed to the transport for further validation. If 1201 that validation fails, the server MUST fail the TLS handshake and 1202 send an illegal_parameter alert. 1204 Combining address validation with the other uses of HelloRetryRequest 1205 ensures that there are fewer ways in which an additional round-trip 1206 can be added to the handshake. In particular, this makes it possible 1207 to combine a request for address validation with a request for a 1208 different client key share. 1210 If TLS needs to send a HelloRetryRequest for other reasons, it needs 1211 to ensure that it can correctly identify the reason that the 1212 HelloRetryRequest was generated. During the processing of a second 1213 ClientHello, TLS does not need to consult the transport protocol 1214 regarding address validation if address validation was not requested 1215 originally. In such cases, the cookie extension could either be 1216 absent or it could indicate that an address validation token is not 1217 present. 1219 7.1.1. Stateless Address Validation 1221 A server can use the cookie extension to store all state necessary to 1222 continue the connection. This allows a server to avoid committing 1223 state for clients that have unvalidated source addresses. 1225 For instance, a server could use a statically-configured key to 1226 encrypt the information that it requires and include that information 1227 in the cookie. In addition to address validation information, a 1228 server that uses encryption also needs to be able recover the hash of 1229 the ClientHello and its length, plus any information it needs in 1230 order to reconstruct the HelloRetryRequest. 1232 7.1.2. Sending HelloRetryRequest 1234 A server does not need to maintain state for the connection when 1235 sending a HelloRetryRequest message. This might be necessary to 1236 avoid creating a denial of service exposure for the server. However, 1237 this means that information about the transport will be lost at the 1238 server. This includes the stream offset of stream 0, the packet 1239 number that the server selects, and any opportunity to measure round 1240 trip time. 1242 A server MUST send a TLS HelloRetryRequest in a Retry packet. Using 1243 a Retry packet causes the client to reset stream offsets. It also 1244 avoids the need for the server select an initial packet number, which 1245 would need to be remembered so that subsequent packets could be 1246 correctly numbered. 1248 A HelloRetryRequest message MUST NOT be split between multiple Retry 1249 packets. This means that HelloRetryRequest is subject to the same 1250 size constraints as a ClientHello (see Section 4.4). 1252 A client might send multiple Initial packets in response to loss. If 1253 a server sends a Retry packet in response to an Initial packet, it 1254 does not have to generate the same Retry packet each time. 1255 Variations in Retry packet, if used by a client, could lead to 1256 multiple connections derived from the same ClientHello. Reuse of the 1257 client nonce is not supported by TLS and could lead to security 1258 vulnerabilities. Clients that receive multiple Retry packets MUST 1259 use only one and discard the remainder. 1261 7.2. NewSessionTicket Address Validation 1263 The ticket in the TLS NewSessionTicket message allows a server to 1264 provide a client with a similar sort of token. When a client resumes 1265 a TLS connection - whether or not 0-RTT is attempted - it includes 1266 the ticket in the handshake message. As with the HelloRetryRequest 1267 cookie, the server includes the address validation token in the 1268 ticket. TLS provides the token it extracts from the session ticket 1269 to the transport when it asks whether source address validation is 1270 needed. 1272 If both a HelloRetryRequest cookie and a session ticket are present 1273 in the ClientHello, only the token from the cookie is passed to the 1274 transport. The presence of a cookie indicates that this is a second 1275 ClientHello - the token from the session ticket will have been 1276 provided to the transport when it appeared in the first ClientHello. 1278 A server can send a NewSessionTicket message at any time. This 1279 allows it to update the state - and the address validation token - 1280 that is included in the ticket. This might be done to refresh the 1281 ticket or token, or it might be generated in response to changes in 1282 the state of the connection. QUIC can request that a 1283 NewSessionTicket be sent by providing a new address validation token. 1285 A server that intends to support 0-RTT SHOULD provide an address 1286 validation token immediately after completing the TLS handshake. 1288 7.3. Address Validation Token Integrity 1290 TLS MUST provide integrity protection for address validation token 1291 unless the transport guarantees integrity protection by other means. 1292 For a NewSessionTicket that includes confidential information - such 1293 as the resumption secret - including the token under authenticated 1294 encryption ensures that the token gains both confidentiality and 1295 integrity protection without duplicating the overheads of that 1296 protection. 1298 8. Pre-handshake QUIC Messages 1300 Implementations MUST NOT exchange data on any stream other than 1301 stream 0 without packet protection. QUIC requires the use of several 1302 types of frame for managing loss detection and recovery during this 1303 phase. In addition, it might be useful to use the data acquired 1304 during the exchange of unauthenticated messages for congestion 1305 control. 1307 This section generally only applies to TLS handshake messages from 1308 both peers and acknowledgments of the packets carrying those 1309 messages. In many cases, the need for servers to provide 1310 acknowledgments is minimal, since the messages that clients send are 1311 small and implicitly acknowledged by the server's responses. 1313 The actions that a peer takes as a result of receiving an 1314 unauthenticated packet needs to be limited. In particular, state 1315 established by these packets cannot be retained once record 1316 protection commences. 1318 There are several approaches possible for dealing with 1319 unauthenticated packets prior to handshake completion: 1321 o discard and ignore them 1322 o use them, but reset any state that is established once the 1323 handshake completes 1325 o use them and authenticate them afterwards; failing the handshake 1326 if they can't be authenticated 1328 o save them and use them when they can be properly authenticated 1330 o treat them as a fatal error 1332 Different strategies are appropriate for different types of data. 1333 This document proposes that all strategies are possible depending on 1334 the type of message. 1336 o Transport parameters are made usable and authenticated as part of 1337 the TLS handshake (see Section 9.2). 1339 o Most unprotected messages are treated as fatal errors when 1340 received except for the small number necessary to permit the 1341 handshake to complete (see Section 8.1). 1343 o Protected packets can either be discarded or saved and later used 1344 (see Section 8.3). 1346 8.1. Unprotected Packets Prior to Handshake Completion 1348 This section describes the handling of messages that are sent and 1349 received prior to the completion of the TLS handshake. 1351 Sending and receiving unprotected messages is hazardous. Unless 1352 expressly permitted, receipt of an unprotected message of any kind 1353 MUST be treated as a fatal error. 1355 8.1.1. STREAM Frames 1357 "STREAM" frames for stream 0 are permitted. These carry the TLS 1358 handshake messages. Once 1-RTT keys are available, unprotected 1359 "STREAM" frames on stream 0 can be ignored. 1361 Receiving unprotected "STREAM" frames for other streams MUST be 1362 treated as a fatal error. 1364 8.1.2. ACK Frames 1366 "ACK" frames are permitted prior to the handshake being complete. 1367 Information learned from "ACK" frames cannot be entirely relied upon, 1368 since an attacker is able to inject these packets. Timing and packet 1369 retransmission information from "ACK" frames is critical to the 1370 functioning of the protocol, but these frames might be spoofed or 1371 altered. 1373 Endpoints MUST NOT use an "ACK" frame in an unprotected packet to 1374 acknowledge packets that were protected by 0-RTT or 1-RTT keys. An 1375 endpoint MUST treat receipt of an "ACK" frame in an unprotected 1376 packet that claims to acknowledge protected packets as a connection 1377 error of type OPTIMISTIC_ACK. An endpoint that can read protected 1378 data is always able to send protected data. 1380 Note: 0-RTT data can be acknowledged by the server as it receives 1381 it, but any packets containing acknowledgments of 0-RTT data 1382 cannot have packet protection removed by the client until the TLS 1383 handshake is complete. The 1-RTT keys necessary to remove packet 1384 protection cannot be derived until the client receives all server 1385 handshake messages. 1387 An endpoint SHOULD use data from "ACK" frames carried in unprotected 1388 packets or packets protected with 0-RTT keys only during the initial 1389 handshake. All "ACK" frames contained in unprotected packets that 1390 are received after successful receipt of a packet protected with 1391 1-RTT keys MUST be discarded. An endpoint SHOULD therefore include 1392 acknowledgments for unprotected and any packets protected with 0-RTT 1393 keys until it sees an acknowledgment for a packet that is both 1394 protected with 1-RTT keys and contains an "ACK" frame. 1396 8.1.3. Updates to Data and Stream Limits 1398 "MAX_DATA", "MAX_STREAM_DATA", "BLOCKED", "STREAM_BLOCKED", and 1399 "MAX_STREAM_ID" frames MUST NOT be sent unprotected. 1401 Though data is exchanged on stream 0, the initial flow control window 1402 on that stream is sufficiently large to allow the TLS handshake to 1403 complete. This limits the maximum size of the TLS handshake and 1404 would prevent a server or client from using an abnormally large 1405 certificate chain. 1407 Stream 0 is exempt from the connection-level flow control window. 1409 Consequently, there is no need to signal being blocked on flow 1410 control. 1412 Similarly, there is no need to increase the number of allowed streams 1413 until the handshake completes. 1415 8.1.4. Handshake Failures 1417 The "CONNECTION_CLOSE" frame MAY be sent by either endpoint in a 1418 Handshake packet. This allows an endpoint to signal a fatal error 1419 with connection establishment. A "STREAM" frame carrying a TLS alert 1420 MAY be included in the same packet. 1422 8.1.5. Address Verification 1424 In order to perform source-address verification before the handshake 1425 is complete, "PATH_CHALLENGE" and "PATH_RESPONSE" frames MAY be 1426 exchanged unprotected. 1428 8.1.6. Denial of Service with Unprotected Packets 1430 Accepting unprotected - specifically unauthenticated - packets 1431 presents a denial of service risk to endpoints. An attacker that is 1432 able to inject unprotected packets can cause a recipient to drop even 1433 protected packets with a matching packet number. The spurious packet 1434 shadows the genuine packet, causing the genuine packet to be ignored 1435 as redundant. 1437 Once the TLS handshake is complete, both peers MUST ignore 1438 unprotected packets. From that point onward, unprotected messages 1439 can be safely dropped. 1441 Since only TLS handshake packets and acknowledgments are sent in the 1442 clear, an attacker is able to force implementations to rely on 1443 retransmission for packets that are lost or shadowed. Thus, an 1444 attacker that intends to deny service to an endpoint has to drop or 1445 shadow protected packets in order to ensure that their victim 1446 continues to accept unprotected packets. The ability to shadow 1447 packets means that an attacker does not need to be on path. 1449 In addition to causing valid packets to be dropped, an attacker can 1450 generate packets with an intent of causing the recipient to expend 1451 processing resources. See Section 10.2 for a discussion of these 1452 risks. 1454 To avoid receiving TLS packets that contain no useful data, a TLS 1455 implementation MUST reject empty TLS handshake records and any record 1456 that is not permitted by the TLS state machine. Any TLS application 1457 data or alerts that are received prior to the end of the handshake 1458 MUST be treated as a connection error of type PROTOCOL_VIOLATION. 1460 8.2. Use of 0-RTT Keys 1462 If 0-RTT keys are available (see Section 5.2), the lack of replay 1463 protection means that restrictions on their use are necessary to 1464 avoid replay attacks on the protocol. 1466 A client MUST only use 0-RTT keys to protect data that is idempotent. 1467 A client MAY wish to apply additional restrictions on what data it 1468 sends prior to the completion of the TLS handshake. A client 1469 otherwise treats 0-RTT keys as equivalent to 1-RTT keys. 1471 A client that receives an indication that its 0-RTT data has been 1472 accepted by a server can send 0-RTT data until it receives all of the 1473 server's handshake messages. A client SHOULD stop sending 0-RTT data 1474 if it receives an indication that 0-RTT data has been rejected. 1476 A server MUST NOT use 0-RTT keys to protect packets. 1478 If a server rejects 0-RTT, then the TLS stream will not include any 1479 TLS records protected with 0-RTT keys. 1481 8.3. Receiving Out-of-Order Protected Frames 1483 Due to reordering and loss, protected packets might be received by an 1484 endpoint before the final TLS handshake messages are received. A 1485 client will be unable to decrypt 1-RTT packets from the server, 1486 whereas a server will be able to decrypt 1-RTT packets from the 1487 client. 1489 Packets protected with 1-RTT keys MAY be stored and later decrypted 1490 and used once the handshake is complete. A server MUST NOT use 1-RTT 1491 protected packets before verifying either the client Finished message 1492 or - in the case that the server has chosen to use a pre-shared key - 1493 the pre-shared key binder (see Section 4.2.8 of [TLS13]). Verifying 1494 these values provides the server with an assurance that the 1495 ClientHello has not been modified. 1497 A server could receive packets protected with 0-RTT keys prior to 1498 receiving a TLS ClientHello. The server MAY retain these packets for 1499 later decryption in anticipation of receiving a ClientHello. 1501 Receiving and verifying the TLS Finished message is critical in 1502 ensuring the integrity of the TLS handshake. A server MUST NOT use 1503 protected packets from the client prior to verifying the client 1504 Finished message if its response depends on client authentication. 1506 9. QUIC-Specific Additions to the TLS Handshake 1508 QUIC uses the TLS handshake for more than just negotiation of 1509 cryptographic parameters. The TLS handshake validates protocol 1510 version selection, provides preliminary values for QUIC transport 1511 parameters, and allows a server to perform return routeability checks 1512 on clients. 1514 9.1. Protocol and Version Negotiation 1516 The QUIC version negotiation mechanism is used to negotiate the 1517 version of QUIC that is used prior to the completion of the 1518 handshake. However, this packet is not authenticated, enabling an 1519 active attacker to force a version downgrade. 1521 To ensure that a QUIC version downgrade is not forced by an attacker, 1522 version information is copied into the TLS handshake, which provides 1523 integrity protection for the QUIC negotiation. This does not prevent 1524 version downgrade prior to the completion of the handshake, though it 1525 means that a downgrade causes a handshake failure. 1527 TLS uses Application Layer Protocol Negotiation (ALPN) [RFC7301] to 1528 select an application protocol. The application-layer protocol MAY 1529 restrict the QUIC versions that it can operate over. Servers MUST 1530 select an application protocol compatible with the QUIC version that 1531 the client has selected. 1533 If the server cannot select a compatible combination of application 1534 protocol and QUIC version, it MUST abort the connection. A client 1535 MUST abort a connection if the server picks an incompatible 1536 combination of QUIC version and ALPN identifier. 1538 9.2. QUIC Transport Parameters Extension 1540 QUIC transport parameters are carried in a TLS extension. Different 1541 versions of QUIC might define a different format for this struct. 1543 Including transport parameters in the TLS handshake provides 1544 integrity protection for these values. 1546 enum { 1547 quic_transport_parameters(26), (65535) 1548 } ExtensionType; 1550 The "extension_data" field of the quic_transport_parameters extension 1551 contains a value that is defined by the version of QUIC that is in 1552 use. The quic_transport_parameters extension carries a 1553 TransportParameters when the version of QUIC defined in 1554 [QUIC-TRANSPORT] is used. 1556 The quic_transport_parameters extension is carried in the ClientHello 1557 and the EncryptedExtensions messages during the handshake. 1559 10. Security Considerations 1561 There are likely to be some real clangers here eventually, but the 1562 current set of issues is well captured in the relevant sections of 1563 the main text. 1565 Never assume that because it isn't in the security considerations 1566 section it doesn't affect security. Most of this document does. 1568 10.1. Packet Reflection Attack Mitigation 1570 A small ClientHello that results in a large block of handshake 1571 messages from a server can be used in packet reflection attacks to 1572 amplify the traffic generated by an attacker. 1574 Certificate caching [RFC7924] can reduce the size of the server's 1575 handshake messages significantly. 1577 QUIC requires that the packet containing a ClientHello be padded to a 1578 minimum size. A server is less likely to generate a packet 1579 reflection attack if the data it sends is a small multiple of this 1580 size. A server SHOULD use a HelloRetryRequest if the size of the 1581 handshake messages it sends is likely to significantly exceed the 1582 size of the packet containing the ClientHello. 1584 10.2. Peer Denial of Service 1586 QUIC, TLS and HTTP/2 all contain a messages that have legitimate uses 1587 in some contexts, but that can be abused to cause a peer to expend 1588 processing resources without having any observable impact on the 1589 state of the connection. If processing is disproportionately large 1590 in comparison to the observable effects on bandwidth or state, then 1591 this could allow a malicious peer to exhaust processing capacity 1592 without consequence. 1594 QUIC prohibits the sending of empty "STREAM" frames unless they are 1595 marked with the FIN bit. This prevents "STREAM" frames from being 1596 sent that only waste effort. 1598 TLS records SHOULD always contain at least one octet of a handshake 1599 messages or alert. Records containing only padding are permitted 1600 during the handshake, but an excessive number might be used to 1601 generate unnecessary work. Once the TLS handshake is complete, 1602 endpoints MUST NOT send TLS application data records. Receiving TLS 1603 application data MUST be treated as a connection error of type 1604 PROTOCOL_VIOLATION. 1606 While there are legitimate uses for some redundant packets, 1607 implementations SHOULD track redundant packets and treat excessive 1608 volumes of any non-productive packets as indicative of an attack. 1610 11. Error Codes 1612 This section defines error codes from the error code space used in 1613 [QUIC-TRANSPORT]. 1615 The following error codes are defined when TLS is used for the crypto 1616 handshake: 1618 TLS_HANDSHAKE_FAILED (0x201): The TLS handshake failed. 1620 TLS_FATAL_ALERT_GENERATED (0x202): A TLS fatal alert was sent, 1621 causing the TLS connection to end prematurely. 1623 TLS_FATAL_ALERT_RECEIVED (0x203): A TLS fatal alert was received, 1624 causing the TLS connection to end prematurely. 1626 12. IANA Considerations 1628 This document does not create any new IANA registries, but it 1629 registers the values in the following registries: 1631 o QUIC Transport Error Codes Registry [QUIC-TRANSPORT] - IANA is to 1632 register the three error codes found in Section 11, these are 1633 summarized in Table 1. 1635 o TLS ExtensionsType Registry [TLS-REGISTRIES] - IANA is to register 1636 the quic_transport_parameters extension found in Section 9.2. 1637 Assigning 26 to the extension would be greatly appreciated. The 1638 Recommended column is to be marked Yes. The TLS 1.3 Column is to 1639 include CH and EE. 1641 o TLS Exporter Label Registry [TLS-REGISTRIES] - IANA is requested 1642 to register "EXPORTER-QUIC 0rtt" from Section 5.3.3; "EXPORTER- 1643 QUIC client 1rtt" and "EXPORTER-QUIC server 1-RTT" from 1644 Section 5.3.4. The DTLS column is to be marked No. The 1645 Recommended column is to be marked Yes. 1647 +-------+---------------------------+---------------+---------------+ 1648 | Value | Error | Description | Specification | 1649 +-------+---------------------------+---------------+---------------+ 1650 | 0x201 | TLS_HANDSHAKE_FAILED | TLS handshake | Section 11 | 1651 | | | failure | | 1652 | | | | | 1653 | 0x202 | TLS_FATAL_ALERT_GENERATED | Sent TLS | Section 11 | 1654 | | | alert | | 1655 | | | | | 1656 | 0x203 | TLS_FATAL_ALERT_RECEIVED | Receives TLS | Section 11 | 1657 | | | alert | | 1658 +-------+---------------------------+---------------+---------------+ 1660 Table 1: QUIC Transport Error Codes for TLS 1662 13. References 1664 13.1. Normative References 1666 [AEAD] McGrew, D., "An Interface and Algorithms for Authenticated 1667 Encryption", RFC 5116, DOI 10.17487/RFC5116, January 2008, 1668 . 1670 [FIPS180] Department of Commerce, National., "NIST FIPS 180-4, 1671 Secure Hash Standard", March 2012, 1672 . 1675 [HKDF] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand 1676 Key Derivation Function (HKDF)", RFC 5869, 1677 DOI 10.17487/RFC5869, May 2010, 1678 . 1680 [QUIC-TRANSPORT] 1681 Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based 1682 Multiplexed and Secure Transport", draft-ietf-quic- 1683 transport-11 (work in progress), April 2018. 1685 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1686 Requirement Levels", BCP 14, RFC 2119, 1687 DOI 10.17487/RFC2119, March 1997, 1688 . 1690 [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, 1691 "Transport Layer Security (TLS) Application-Layer Protocol 1692 Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301, 1693 July 2014, . 1695 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1696 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1697 May 2017, . 1699 [TLS-REGISTRIES] 1700 Salowey, J. and S. Turner, "IANA Registry Updates for TLS 1701 and DTLS", draft-ietf-tls-iana-registry-updates-04 (work 1702 in progress), February 2018. 1704 [TLS13] Rescorla, E., "The Transport Layer Security (TLS) Protocol 1705 Version 1.3", draft-ietf-tls-tls13-21 (work in progress), 1706 July 2017. 1708 13.2. Informative References 1710 [AEBounds] 1711 Luykx, A. and K. Paterson, "Limits on Authenticated 1712 Encryption Use in TLS", March 2016, 1713 . 1715 [QUIC-HTTP] 1716 Bishop, M., Ed., "Hypertext Transfer Protocol (HTTP) over 1717 QUIC", draft-ietf-quic-http-11 (work in progress), April 1718 2018. 1720 [QUIC-RECOVERY] 1721 Iyengar, J., Ed. and I. Swett, Ed., "QUIC Loss Detection 1722 and Congestion Control", draft-ietf-quic-recovery-11 (work 1723 in progress), April 2018. 1725 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, 1726 DOI 10.17487/RFC2818, May 2000, 1727 . 1729 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 1730 Housley, R., and W. Polk, "Internet X.509 Public Key 1731 Infrastructure Certificate and Certificate Revocation List 1732 (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, 1733 . 1735 [RFC7924] Santesson, S. and H. Tschofenig, "Transport Layer Security 1736 (TLS) Cached Information Extension", RFC 7924, 1737 DOI 10.17487/RFC7924, July 2016, 1738 . 1740 13.3. URIs 1742 [1] https://mailarchive.ietf.org/arch/search/?email_list=quic 1744 [2] https://github.com/quicwg 1746 [3] https://github.com/quicwg/base-drafts/labels/-tls 1748 Appendix A. Contributors 1750 Ryan Hamilton was originally an author of this specification. 1752 Appendix B. Acknowledgments 1754 This document has benefited from input from Dragana Damjanovic, 1755 Christian Huitema, Jana Iyengar, Adam Langley, Roberto Peon, Eric 1756 Rescorla, Ian Swett, and many others. 1758 Appendix C. Change Log 1760 *RFC Editor's Note:* Please remove this section prior to 1761 publication of a final version of this document. 1763 Issue and pull request numbers are listed with a leading octothorp. 1765 C.1. Since draft-ietf-quic-tls-10 1767 o No significant changes. 1769 C.2. Since draft-ietf-quic-tls-09 1771 o Cleaned up key schedule and updated the salt used for handshake 1772 packet protection (#1077) 1774 C.3. Since draft-ietf-quic-tls-08 1776 o Specify value for max_early_data_size to enable 0-RTT (#942) 1778 o Update key derivation function (#1003, #1004) 1780 C.4. Since draft-ietf-quic-tls-07 1782 o Handshake errors can be reported with CONNECTION_CLOSE (#608, 1783 #891) 1785 C.5. Since draft-ietf-quic-tls-05 1787 No significant changes. 1789 C.6. Since draft-ietf-quic-tls-04 1791 o Update labels used in HKDF-Expand-Label to match TLS 1.3 (#642) 1793 C.7. Since draft-ietf-quic-tls-03 1795 No significant changes. 1797 C.8. Since draft-ietf-quic-tls-02 1799 o Updates to match changes in transport draft 1801 C.9. Since draft-ietf-quic-tls-01 1803 o Use TLS alerts to signal TLS errors (#272, #374) 1805 o Require ClientHello to fit in a single packet (#338) 1807 o The second client handshake flight is now sent in the clear (#262, 1808 #337) 1810 o The QUIC header is included as AEAD Associated Data (#226, #243, 1811 #302) 1813 o Add interface necessary for client address validation (#275) 1815 o Define peer authentication (#140) 1817 o Require at least TLS 1.3 (#138) 1819 o Define transport parameters as a TLS extension (#122) 1821 o Define handling for protected packets before the handshake 1822 completes (#39) 1824 o Decouple QUIC version and ALPN (#12) 1826 C.10. Since draft-ietf-quic-tls-00 1828 o Changed bit used to signal key phase 1830 o Updated key phase markings during the handshake 1832 o Added TLS interface requirements section 1833 o Moved to use of TLS exporters for key derivation 1835 o Moved TLS error code definitions into this document 1837 C.11. Since draft-thomson-quic-tls-01 1839 o Adopted as base for draft-ietf-quic-tls 1841 o Updated authors/editors list 1843 o Added status note 1845 Authors' Addresses 1847 Martin Thomson (editor) 1848 Mozilla 1850 Email: martin.thomson@gmail.com 1852 Sean Turner (editor) 1853 sn3rd 1855 Email: sean@sn3rd.com