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'PKCS1' ** Obsolete normative reference: RFC 2246 (Obsoleted by RFC 4346) ** Obsolete normative reference: RFC 4346 (Obsoleted by RFC 5246) ** Obsolete normative reference: RFC 4366 (Obsoleted by RFC 5246, RFC 6066) ** Obsolete normative reference: RFC 5246 (Obsoleted by RFC 8446) -- Possible downref: Non-RFC (?) normative reference: ref. 'SECG-SEC2' == Outdated reference: A later version (-28) exists of draft-ietf-tls-tls13-02 -- Obsolete informational reference (is this intentional?): RFC 4492 (Obsoleted by RFC 8422) Summary: 4 errors (**), 0 flaws (~~), 9 warnings (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 TLS Working Group Y. Nir 3 Internet-Draft Check Point 4 Intended status: Standards Track July 6, 2015 5 Expires: January 7, 2016 7 Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer 8 Security (TLS) Versions 1.2 and Earlier 9 draft-ietf-tls-rfc4492bis-03 11 Abstract 13 This document describes key exchange algorithms based on Elliptic 14 Curve Cryptography (ECC) for the Transport Layer Security (TLS) 15 protocol. In particular, it specifies the use of Ephemeral Elliptic 16 Curve Diffie-Hellman (ECDHE) key agreement in a TLS handshake and the 17 use of Elliptic Curve Digital Signature Algorithm (ECDSA) as a new 18 authentication mechanism. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on January 7, 2016. 37 Copyright Notice 39 Copyright (c) 2015 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 1.1. Conventions Used in This Document . . . . . . . . . . . . 4 56 2. Key Exchange Algorithm . . . . . . . . . . . . . . . . . . . 4 57 2.1. ECDHE_ECDSA . . . . . . . . . . . . . . . . . . . . . . . 5 58 2.2. ECDHE_RSA . . . . . . . . . . . . . . . . . . . . . . . . 6 59 2.3. ECDH_anon . . . . . . . . . . . . . . . . . . . . . . . . 6 60 3. Client Authentication . . . . . . . . . . . . . . . . . . . . 6 61 3.1. ECDSA_sign . . . . . . . . . . . . . . . . . . . . . . . 7 62 4. TLS Extensions for ECC . . . . . . . . . . . . . . . . . . . 7 63 5. Data Structures and Computations . . . . . . . . . . . . . . 8 64 5.1. Client Hello Extensions . . . . . . . . . . . . . . . . . 8 65 5.1.1. Supported Elliptic Curves Extension . . . . . . . . . 10 66 5.1.2. Supported Point Formats Extension . . . . . . . . . . 11 67 5.2. Server Hello Extension . . . . . . . . . . . . . . . . . 11 68 5.3. Server Certificate . . . . . . . . . . . . . . . . . . . 12 69 5.4. Server Key Exchange . . . . . . . . . . . . . . . . . . . 13 70 5.5. Certificate Request . . . . . . . . . . . . . . . . . . . 17 71 5.6. Client Certificate . . . . . . . . . . . . . . . . . . . 18 72 5.7. Client Key Exchange . . . . . . . . . . . . . . . . . . . 19 73 5.8. Certificate Verify . . . . . . . . . . . . . . . . . . . 21 74 5.9. Elliptic Curve Certificates . . . . . . . . . . . . . . . 22 75 5.10. ECDH, ECDSA, and RSA Computations . . . . . . . . . . . . 22 76 6. Cipher Suites . . . . . . . . . . . . . . . . . . . . . . . . 23 77 7. Security Considerations . . . . . . . . . . . . . . . . . . . 24 78 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 79 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25 80 10. Version History for This Draft . . . . . . . . . . . . . . . 25 81 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 26 82 11.1. Normative References . . . . . . . . . . . . . . . . . . 26 83 11.2. Informative References . . . . . . . . . . . . . . . . . 27 84 Appendix A. Equivalent Curves (Informative) . . . . . . . . . . 27 85 Appendix B. Differences from RFC 4492 . . . . . . . . . . . . . 28 86 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 29 88 1. Introduction 90 Elliptic Curve Cryptography (ECC) is emerging as an attractive 91 public-key cryptosystem, in particular for mobile (i.e., wireless) 92 environments. Compared to currently prevalent cryptosystems such as 93 RSA, ECC offers equivalent security with smaller key sizes. This is 94 illustrated in the following table, based on [Lenstra_Verheul], which 95 gives approximate comparable key sizes for symmetric- and asymmetric- 96 key cryptosystems based on the best-known algorithms for attacking 97 them. 99 +-----------+-----+------------+ 100 | Symmetric | ECC | DH/DSA/RSA | 101 +-----------+-----+------------+ 102 | 80 | 163 | 1024 | 103 | 112 | 233 | 2048 | 104 | 128 | 283 | 3072 | 105 | 192 | 409 | 7680 | 106 | 256 | 571 | 15360 | 107 +-----------+-----+------------+ 109 Table 1: Comparable Key Sizes (in bits) 111 Smaller key sizes result in savings for power, memory, bandwidth, and 112 computational cost that make ECC especially attractive for 113 constrained environments. 115 This document describes additions to TLS to support ECC, applicable 116 to TLS versions 1.0 [RFC2246], 1.1 [RFC4346], and 1.2 [RFC5246]. The 117 use of ECC in TLS 1.3 is defined in [I-D.ietf-tls-tls13], and is 118 explicitly out of scope for this document. In particular, this 119 document defines: 121 o the use of the Elliptic Curve Diffie-Hellman key agreement scheme 122 with ephemeral keys to establish the TLS premaster secret, and 123 o the use of ECDSA certificates for authentication of TLS peers. 125 The remainder of this document is organized as follows. Section 2 126 provides an overview of ECC-based key exchange algorithms for TLS. 127 Section 3 describes the use of ECC certificates for client 128 authentication. TLS extensions that allow a client to negotiate the 129 use of specific curves and point formats are presented in Section 4. 130 Section 5 specifies various data structures needed for an ECC-based 131 handshake, their encoding in TLS messages, and the processing of 132 those messages. Section 6 defines ECC-based cipher suites and 133 identifies a small subset of these as recommended for all 134 implementations of this specification. Section 7 discusses security 135 considerations. Section 8 describes IANA considerations for the name 136 spaces created by this document's predecessor. Section 9 gives 137 acknowledgements. Appendix B provides differences from [RFC4492], 138 the document that this one replaces. 140 Implementation of this specification requires familiarity with TLS, 141 TLS extensions [RFC4366], and ECC (TBD: reference Wikipedia here?). 143 1.1. Conventions Used in This Document 145 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 146 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 147 document are to be interpreted as described in [RFC2119]. 149 2. Key Exchange Algorithm 151 This document defines three new ECC-based key exchange algorithms for 152 TLS. All of them use Ephemeral ECDH (ECDHE) to compute the TLS 153 premaster secret, and they differ only in the mechanism (if any) used 154 to authenticate them. The derivation of the TLS master secret from 155 the premaster secret and the subsequent generation of bulk 156 encryption/MAC keys and initialization vectors is independent of the 157 key exchange algorithm and not impacted by the introduction of ECC. 159 The table below summarizes the new key exchange algorithms, which 160 mimic DHE_DSS, DHE_RSA, and DH_anon, respectively. 162 +-------------+---------------------------------------+ 163 | Algorithm | Description | 164 +-------------+---------------------------------------+ 165 | ECDHE_ECDSA | Ephemeral ECDH with ECDSA signatures. | 166 | ECDHE_RSA | Ephemeral ECDH with RSA signatures. | 167 | ECDH_anon | Anonymous ECDH, no signatures. | 168 +-------------+---------------------------------------+ 170 Table 2: ECC Key Exchange Algorithms 172 The ECDHE_ECDSA and ECDHE_RSA key exchange mechanisms provide forward 173 secrecy. With ECDHE_RSA, a server can reuse its existing RSA 174 certificate and easily comply with a constrained client's elliptic 175 curve p references (see Section 4). However, the computational cost 176 incurred by a server is higher for ECDHE_RSA than for the traditional 177 RSA key exchange, which does not provide forward secrecy. 179 The anonymous key exchange algorithm does not provide authentication 180 of the server or the client. Like other anonymous TLS key exchanges, 181 it is subject to man-in-the-middle attacks. Implementations of this 182 algorithm SHOULD provide authentication by other means. 184 Note that there is no structural difference between ECDH and ECDSA 185 keys. A certificate issuer may use X.509 v3 keyUsage and 186 extendedKeyUsage extensions to restrict the use of an ECC public key 187 to certain computations. This document refers to an ECC key as ECDH- 188 capable if its use in ECDH is permitted. ECDSA-capable is defined 189 similarly. 191 Client Server 192 ------ ------ 193 ClientHello --------> 194 ServerHello 195 Certificate* 196 ServerKeyExchange* 197 CertificateRequest*+ 198 <-------- ServerHelloDone 199 Certificate*+ 200 ClientKeyExchange 201 CertificateVerify*+ 202 [ChangeCipherSpec] 203 Finished --------> 204 [ChangeCipherSpec] 205 <-------- Finished 206 Application Data <-------> Application Data 207 * message is not sent under some conditions 208 + message is not sent unless client authentication 209 is desired 211 Figure 1: Message flow in a full TLS handshake 213 Figure 1 shows all messages involved in the TLS key establishment 214 protocol (aka full handshake). The addition of ECC has direct impact 215 only on the ClientHello, the ServerHello, the server's Certificate 216 message, the ServerKeyExchange, the ClientKeyExchange, the 217 CertificateRequest, the client's Certificate message, and the 218 CertificateVerify. Next, we describe the ECC key exchange algorithm 219 in greater detail in terms of the content and processing of these 220 messages. For ease of exposition, we defer discussion of client 221 authentication and associated messages (identified with a + in 222 Figure 1) until Section 3 and of the optional ECC-specific extensions 223 (which impact the Hello messages) until Section 4. 225 2.1. ECDHE_ECDSA 227 In ECDHE_ECDSA, the server's certificate MUST contain an ECDSA- 228 capable public key and be signed with ECDSA. 230 The server sends its ephemeral ECDH public key and a specification of 231 the corresponding curve in the ServerKeyExchange message. These 232 parameters MUST be signed with ECDSA using the private key 233 corresponding to the public key in the server's Certificate. 235 The client generates an ECDH key pair on the same curve as the 236 server's ephemeral ECDH key and sends its public key in the 237 ClientKeyExchange message. 239 Both client and server perform an ECDH operation Section 5.10 and use 240 the resultant shared secret as the premaster secret. 242 2.2. ECDHE_RSA 244 This key exchange algorithm is the same as ECDHE_ECDSA except that 245 the server's certificate MUST contain an RSA public key authorized 246 for signing, and that the signature in the ServerKeyExchange message 247 must be computed with the corresponding RSA private key. The server 248 certificate MUST be signed with RSA. 250 2.3. ECDH_anon 252 In ECDH_anon, the server's Certificate, the CertificateRequest, the 253 client's Certificate, and the CertificateVerify messages MUST NOT be 254 sent. 256 The server MUST send an ephemeral ECDH public key and a specification 257 of the corresponding curve in the ServerKeyExchange message. These 258 parameters MUST NOT be signed. 260 The client generates an ECDH key pair on the same curve as the 261 server's ephemeral ECDH key and sends its public key in the 262 ClientKeyExchange message. 264 Both client and server perform an ECDH operation and use the 265 resultant shared secret as the premaster secret. All ECDH 266 calculations are performed as specified in Section 5.10. 268 Note that while the ECDHE_ECDSA and ECDHE_RSA key exchange algorithms 269 require the server's certificate to be signed with a particular 270 signature scheme, this specification (following the similar cases of 271 DHE_DSS, and DHE_RSA in the TLS base documents) does not impose 272 restrictions on signature schemes used elsewhere in the certificate 273 chain. (Often such restrictions will be useful, and it is expected 274 that this will be taken into account in certification authorities' 275 signing practices. However, such restrictions are not strictly 276 required in general: Even if it is beyond the capabilities of a 277 client to completely validate a given chain, the client may be able 278 to validate the server's certificate by relying on a trusted 279 certification authority whose certificate appears as one of the 280 intermediate certificates in the chain.) 282 3. Client Authentication 284 This document defines a client authentication mechanism, named after 285 the type of client certificate involved: ECDSA_sign. The ECDSA_sign 286 mechanism is usable with any of the non-anonymous ECC key exchange 287 algorithms described in Section 2 as well as other non-anonymous 288 (non-ECC) key exchange algorithms defined in TLS. 290 The server can request ECC-based client authentication by including 291 this certificate type in its CertificateRequest message. The client 292 must check if it possesses a certificate appropriate for the method 293 suggested by the server and is willing to use it for authentication. 295 If these conditions are not met, the client should send a client 296 Certificate message containing no certificates. In this case, the 297 ClientKeyExchange should be sent as described in Section 2, and the 298 CertificateVerify should not be sent. If the server requires client 299 authentication, it may respond with a fatal handshake failure alert. 301 If the client has an appropriate certificate and is willing to use it 302 for authentication, it must send that certificate in the client's 303 Certificate message (as per Section 5.6) and prove possession of the 304 private key corresponding to the certified key. The process of 305 determining an appropriate certificate and proving possession is 306 different for each authentication mechanism and described below. 308 NOTE: It is permissible for a server to request (and the client to 309 send) a client certificate of a different type than the server 310 certificate. 312 3.1. ECDSA_sign 314 To use this authentication mechanism, the client MUST possess a 315 certificate containing an ECDSA-capable public key and signed with 316 ECDSA. 318 The client proves possession of the private key corresponding to the 319 certified key by including a signature in the CertificateVerify 320 message as described in Section 5.8. 322 4. TLS Extensions for ECC 324 Two new TLS extensions are defined in this specification: (i) the 325 Supported Elliptic Curves Extension, and (ii) the Supported Point 326 Formats Extension. These allow negotiating the use of specific 327 curves and point formats (e.g., compressed vs. uncompressed, 328 respectively) during a handshake starting a new session. These 329 extensions are especially relevant for constrained clients that may 330 only support a limited number of curves or point formats. They 331 follow the general approach outlined in [RFC4366]; message details 332 are specified in Section 5. The client enumerates the curves it 333 supports and the point formats it can parse by including the 334 appropriate extensions in its ClientHello message. The server 335 similarly enumerates the point formats it can parse by including an 336 extension in its ServerHello message. 338 A TLS client that proposes ECC cipher suites in its ClientHello 339 message SHOULD include these extensions. Servers implementing ECC 340 cipher suites MUST support these extensions, and when a client uses 341 these extensions, servers MUST NOT negotiate the use of an ECC cipher 342 suite unless they can complete the handshake while respecting the 343 choice of curves and compression techniques specified by the client. 344 This eliminates the possibility that a negotiated ECC handshake will 345 be subsequently aborted due to a client's inability to deal with the 346 server's EC key. 348 The client MUST NOT include these extensions in the ClientHello 349 message if it does not propose any ECC cipher suites. A client that 350 proposes ECC cipher suites may choose not to include these 351 extensions. In this case, the server is free to choose any one of 352 the elliptic curves or point formats listed in Section 5. That 353 section also describes the structure and processing of these 354 extensions in greater detail. 356 In the case of session resumption, the server simply ignores the 357 Supported Elliptic Curves Extension and the Supported Point Formats 358 Extension appearing in the current ClientHello message. These 359 extensions only play a role during handshakes negotiating a new 360 session. 362 5. Data Structures and Computations 364 This section specifies the data structures and computations used by 365 ECC-based key mechanisms specified in the previous three sections. 366 The presentation language used here is the same as that used in TLS. 367 Since this specification extends TLS, these descriptions should be 368 merged with those in the TLS specification and any others that extend 369 TLS. This means that enum types may not specify all possible values, 370 and structures with multiple formats chosen with a select() clause 371 may not indicate all possible cases. 373 5.1. Client Hello Extensions 375 This section specifies two TLS extensions that can be included with 376 the ClientHello message as described in [RFC4366], the Supported 377 Elliptic Curves Extension and the Supported Point Formats Extension. 379 When these extensions are sent: 381 The extensions SHOULD be sent along with any ClientHello message that 382 proposes ECC cipher suites. 384 Meaning of these extensions: 386 These extensions allow a client to enumerate the elliptic curves it 387 supports and/or the point formats it can parse. 389 Structure of these extensions: 391 The general structure of TLS extensions is described in [RFC4366], 392 and this specification adds two new types to ExtensionType. 394 enum { elliptic_curves(10), ec_point_formats(11) } ExtensionType; 396 elliptic_curves (Supported Elliptic Curves Extension): Indicates the 397 set of elliptic curves supported by the client. For this 398 extension, the opaque extension_data field contains 399 EllipticCurveList. See Section 5.1.1 for details. 400 ec_point_formats (Supported Point Formats Extension): Indicates the 401 set of point formats that the client can parse. For this 402 extension, the opaque extension_data field contains 403 ECPointFormatList. See Section 5.1.2 for details. 405 Actions of the sender: 407 A client that proposes ECC cipher suites in its ClientHello message 408 appends these extensions (along with any others), enumerating the 409 curves it supports and the point formats it can parse. Clients 410 SHOULD send both the Supported Elliptic Curves Extension and the 411 Supported Point Formats Extension. If the Supported Point Formats 412 Extension is indeed sent, it MUST contain the value 0 (uncompressed) 413 as one of the items in the list of point formats. 415 Actions of the receiver: 417 A server that receives a ClientHello containing one or both of these 418 extensions MUST use the client's enumerated capabilities to guide its 419 selection of an appropriate cipher suite. One of the proposed ECC 420 cipher suites must be negotiated only if the server can successfully 421 complete the handshake while using the curves and point formats 422 supported by the client (cf. Section 5.3 and Section 5.4). 424 NOTE: A server participating in an ECDHE-ECDSA key exchange may use 425 different curves for (i) the ECDSA key in its certificate, and (ii) 426 the ephemeral ECDH key in the ServerKeyExchange message. The server 427 must consider the extensions in both cases. 429 If a server does not understand the Supported Elliptic Curves 430 Extension, does not understand the Supported Point Formats Extension, 431 or is unable to complete the ECC handshake while restricting itself 432 to the enumerated curves and point formats, it MUST NOT negotiate the 433 use of an ECC cipher suite. Depending on what other cipher suites 434 are proposed by the client and supported by the server, this may 435 result in a fatal handshake failure alert due to the lack of common 436 cipher suites. 438 5.1.1. Supported Elliptic Curves Extension 440 RFC 4492 defined 25 different curves in the NamedCurve registry for 441 use in TLS. Only three have seen any use. This specification is 442 deprecating the rest (with numbers 1-22). This specification also 443 deprecates the explicit curves with identifiers 0xFF01 and 0xFF02. 444 This leaves only the following: 446 enum { 447 deprecated(1..22), 448 secp256r1 (23), secp384r1 (24), secp521r1 (25), 449 reserved (0xFE00..0xFEFF), 450 deprecated(0xFF01..0xFF02), 451 (0xFFFF) 452 } NamedCurve; 454 Note that other specification have since added other values to this 455 enumeration. 457 secp256r1, etc: Indicates support of the corresponding named curve or 458 class of explicitly defined curves. The named curves defined here 459 are those specified in SEC 2 [SECG-SEC2]. Note that many of these 460 curves are also recommended in ANSI X9.62 [ANSI.X9-62.2005] and FIPS 461 186-4 [FIPS.186-4]. Values 0xFE00 through 0xFEFF are reserved for 462 private use. 464 The NamedCurve name space is maintained by IANA. See Section 8 for 465 information on how new value assignments are added. 467 struct { 468 NamedCurve elliptic_curve_list<1..2^16-1> 469 } EllipticCurveList; 471 Items in elliptic_curve_list are ordered according to the client's 472 preferences (favorite choice first). 474 As an example, a client that only supports secp256r1 (aka NIST P-256; 475 value 23 = 0x0017) and secp384r1 (aka NIST P-384; value 24 = 0x0018) 476 and prefers to use secp256r1 would include a TLS extension consisting 477 of the following octets. Note that the first two octets indicate the 478 extension type (Supported Elliptic Curves Extension): 480 00 0A 00 06 00 04 00 17 00 18 482 5.1.2. Supported Point Formats Extension 484 enum { uncompressed (0), ansiX962_compressed_prime (1), 485 ansiX962_compressed_char2 (2), reserved (248..255) 486 } ECPointFormat; 487 struct { 488 ECPointFormat ec_point_format_list<1..2^8-1> 489 } ECPointFormatList; 491 Three point formats were included in the definition of ECPointFormat 492 above. This specification deprecates all but the uncompressed point 493 format. Implementations of this document MUST support the 494 uncompressed format for all of their supported curves, and MUST 495 support no other formats for curves defined in this specification. 496 For backwards compatibility purposes, the point format list extension 497 MUST still be included, and contain exactly one value: the 498 uncomptessed point format (0). 500 The ECPointFormat name space is maintained by IANA. See Section 8 501 for information on how new value assignments are added. 503 Items in ec_point_format_list are ordered according to the client's 504 preferences (favorite choice first). 506 A client compliant with this specification that supports no other 507 curves MUST send the following octets; note that the first two octets 508 indicate the extension type (Supported Point Formats Extension): 510 00 0B 00 02 01 00 512 5.2. Server Hello Extension 514 This section specifies a TLS extension that can be included with the 515 ServerHello message as described in [RFC4366], the Supported Point 516 Formats Extension. 518 When this extension is sent: 520 The Supported Point Formats Extension is included in a ServerHello 521 message in response to a ClientHello message containing the Supported 522 Point Formats Extension when negotiating an ECC cipher suite. 524 Meaning of this extension: 526 This extension allows a server to enumerate the point formats it can 527 parse (for the curve that will appear in its ServerKeyExchange 528 message when using the ECDHE_ECDSA, ECDHE_RSA, or ECDH_anon key 529 exchange algorithm. 531 Structure of this extension: 533 The server's Supported Point Formats Extension has the same structure 534 as the client's Supported Point Formats Extension (see 535 Section 5.1.2). Items in ec_point_format_list here are ordered 536 according to the server's preference (favorite choice first). Note 537 that the server may include items that were not found in the client's 538 list (e.g., the server may prefer to receive points in compressed 539 format even when a client cannot parse this format: the same client 540 may nevertheless be capable of outputting points in compressed 541 format). 543 Actions of the sender: 545 A server that selects an ECC cipher suite in response to a 546 ClientHello message including a Supported Point Formats Extension 547 appends this extension (along with others) to its ServerHello 548 message, enumerating the point formats it can parse. The Supported 549 Point Formats Extension, when used, MUST contain the value 0 550 (uncompressed) as one of the items in the list of point formats. 552 Actions of the receiver: 554 A client that receives a ServerHello message containing a Supported 555 Point Formats Extension MUST respect the server's choice of point 556 formats during the handshake (cf. Section 5.6 and Section 5.7). If 557 no Supported Point Formats Extension is received with the 558 ServerHello, this is equivalent to an extension allowing only the 559 uncompressed point format. 561 5.3. Server Certificate 563 When this message is sent: 565 This message is sent in all non-anonymous ECC-based key exchange 566 algorithms. 568 Meaning of this message: 570 This message is used to authentically convey the server's static 571 public key to the client. The following table shows the server 572 certificate type appropriate for each key exchange algorithm. ECC 573 public keys MUST be encoded in certificates as described in 574 Section 5.9. 576 NOTE: The server's Certificate message is capable of carrying a chain 577 of certificates. The restrictions mentioned in Table 3 apply only to 578 the server's certificate (first in the chain). 580 +-------------+-----------------------------------------------------+ 581 | Algorithm | Server Certificate Type | 582 +-------------+-----------------------------------------------------+ 583 | ECDHE_ECDSA | Certificate MUST contain an ECDSA-capable public | 584 | | key. It MUST be signed with ECDSA. | 585 | ECDHE_RSA | Certificate MUST contain an RSA public key | 586 | | authorized for use in digital signatures. It MUST | 587 | | be signed with RSA. | 588 +-------------+-----------------------------------------------------+ 590 Table 3: Server Certificate Types 592 Structure of this message: 594 Identical to the TLS Certificate format. 596 Actions of the sender: 598 The server constructs an appropriate certificate chain and conveys it 599 to the client in the Certificate message. If the client has used a 600 Supported Elliptic Curves Extension, the public key in the server's 601 certificate MUST respect the client's choice of elliptic curves; in 602 particular, the public key MUST employ a named curve (not the same 603 curve as an explicit curve) unless the client has indicated support 604 for explicit curves of the appropriate type. If the client has used 605 a Supported Point Formats Extension, both the server's public key 606 point and (in the case of an explicit curve) the curve's base point 607 MUST respect the client's choice of point formats. (A server that 608 cannot satisfy these requirements MUST NOT choose an ECC cipher suite 609 in its ServerHello message.) 611 Actions of the receiver: 613 The client validates the certificate chain, extracts the server's 614 public key, and checks that the key type is appropriate for the 615 negotiated key exchange algorithm. (A possible reason for a fatal 616 handshake failure is that the client's capabilities for handling 617 elliptic curves and point formats are exceeded; cf. Section 5.1.) 619 5.4. Server Key Exchange 621 When this message is sent: 623 This message is sent when using the ECDHE_ECDSA, ECDHE_RSA, and 624 ECDH_anon key exchange algorithms. 626 Meaning of this message: 628 This message is used to convey the server's ephemeral ECDH public key 629 (and the corresponding elliptic curve domain parameters) to the 630 client. 632 Structure of this message: 634 enum { explicit_prime (1), explicit_char2 (2), 635 named_curve (3), reserved(248..255) } ECCurveType; 637 explicit_prime: Indicates the elliptic curve domain parameters are 638 conveyed verbosely, and the underlying finite field is a prime 639 field. 640 explicit_char2: Indicates the elliptic curve domain parameters are 641 conveyed verbosely, and the underlying finite field is a 642 characteristic-2 field. 643 named_curve: Indicates that a named curve is used. This option 644 SHOULD be used when applicable. 646 Values 248 through 255 are reserved for private use. 648 The ECCurveType name space is maintained by IANA. See Section 8 for 649 information on how new value assignments are added. 651 struct { 652 opaque a <1..2^8-1>; 653 opaque b <1..2^8-1>; 654 } ECCurve; 656 a, b: These parameters specify the coefficients of the elliptic 657 curve. Each value contains the byte string representation of a 658 field element following the conversion routine in Section 4.3.3 of 659 [ANSI.X9-62.2005]. 661 struct { 662 opaque point <1..2^8-1>; 663 } ECPoint; 664 point: This is the byte string representation of an elliptic curve 665 point following the conversion routine in Section 4.3.6 of 666 [ANSI.X9-62.2005]. This byte string may represent an elliptic 667 curve point in uncompressed or compressed format; it MUST conform 668 to what the client has requested through a Supported Point Formats 669 Extension if this extension was used. 671 enum { 672 ec_basis_trinomial(1), ec_basis_pentanomial(2), 673 (255) 674 } ECBasisType; 675 ec_basis_trinomial: Indicates representation of a characteristic-2 676 field using a trinomial basis. 677 ec_basis_pentanomial: Indicates representation of a characteristic-2 678 field using a pentanomial basis. 680 struct { 681 ECCurveType curve_type; 682 select (curve_type) { 683 case explicit_prime: 684 opaque prime_p <1..2^8-1>; 685 ECCurve curve; 686 ECPoint base; 687 opaque order <1..2^8-1>; 688 opaque cofactor <1..2^8-1>; 689 case explicit_char2: 690 uint16 m; 691 ECBasisType basis; 692 select (basis) { 693 case ec_basis_trinomial: 694 opaque k <1..2^8-1>; 695 case ec_basis_pentanomial: 696 opaque k1 <1..2^8-1>; 697 opaque k2 <1..2^8-1>; 698 opaque k3 <1..2^8-1>; 699 }; 700 ECCurve curve; 701 ECPoint base; 702 opaque order <1..2^8-1>; 703 opaque cofactor <1..2^8-1>; 704 case named_curve: 705 NamedCurve namedcurve; 706 }; 707 } ECParameters; 708 curve_type: This identifies the type of the elliptic curve domain 709 parameters. 710 prime_p: This is the odd prime defining the field Fp. 711 curve: Specifies the coefficients a and b of the elliptic curve E. 712 base: Specifies the base point G on the elliptic curve. 713 order: Specifies the order n of the base point. 714 cofactor: Specifies the cofactor h = #E(Fq)/n, where #E(Fq) 715 represents the number of points on the elliptic curve E defined 716 over the field Fq (either Fp or F2^m). 717 m: This is the degree of the characteristic-2 field F2^m. 718 k: The exponent k for the trinomial basis representation x^m + x^k+1. 720 k1, k2, k3: The exponents for the pentanomial representation x^m + 721 x^k3 + x^k2 + x^k1 + 1 (such that k3 > k2 > k1). 722 namedcurve: Specifies a recommended set of elliptic curve domain 723 parameters. All those values of NamedCurve are allowed that refer 724 to a specific curve. Values of NamedCurve that indicate support 725 for a class of explicitly defined curves are not allowed here 726 (they are only permissible in the ClientHello extension); this 727 applies to arbitrary_explicit_prime_curves(0xFF01) and 728 arbitrary_explicit_char2_curves(0xFF02). 730 struct { 731 ECParameters curve_params; 732 ECPoint public; 733 } ServerECDHParams; 734 curve_params: Specifies the elliptic curve domain parameters 735 associated with the ECDH public key. 736 public: The ephemeral ECDH public key. 738 The ServerKeyExchange message is extended as follows. 740 enum { ec_diffie_hellman } KeyExchangeAlgorithm; 742 ec_diffie_hellman: Indicates the ServerKeyExchange message contains 743 an ECDH public key. 745 select (KeyExchangeAlgorithm) { 746 case ec_diffie_hellman: 747 ServerECDHParams params; 748 Signature signed_params; 749 } ServerKeyExchange; 751 params: Specifies the ECDH public key and associated domain 752 parameters. 753 signed_params: A hash of the params, with the signature appropriate 754 to that hash applied. The private key corresponding to the 755 certified public key in the server's Certificate message is used 756 for signing. 758 enum { ecdsa } SignatureAlgorithm; 759 select (SignatureAlgorithm) { 760 case ecdsa: 761 digitally-signed struct { 762 opaque sha_hash[sha_size]; 763 }; 764 } Signature; 765 ServerKeyExchange.signed_params.sha_hash 766 SHA(ClientHello.random + ServerHello.random + 767 ServerKeyExchange.params); 769 NOTE: SignatureAlgorithm is "rsa" for the ECDHE_RSA key exchange 770 algorithm and "anonymous" for ECDH_anon. These cases are defined in 771 TLS. SignatureAlgorithm is "ecdsa" for ECDHE_ECDSA. ECDSA 772 signatures are generated and verified as described in Section 5.10, 773 and SHA in the above template for sha_hash accordingly may denote a 774 hash algorithm other than SHA-1. As per ANSI X9.62, an ECDSA 775 signature consists of a pair of integers, r and s. The digitally- 776 signed element is encoded as an opaque vector <0..2^16-1>, the 777 contents of which are the DER encoding corresponding to the following 778 ASN.1 notation. 780 Ecdsa-Sig-Value ::= SEQUENCE { 781 r INTEGER, 782 s INTEGER 783 } 785 Actions of the sender: 787 The server selects elliptic curve domain parameters and an ephemeral 788 ECDH public key corresponding to these parameters according to the 789 ECKAS-DH1 scheme from IEEE 1363 [IEEE.P1363.1998]. It conveys this 790 information to the client in the ServerKeyExchange message using the 791 format defined above. 793 Actions of the receiver: 795 The client verifies the signature (when present) and retrieves the 796 server's elliptic curve domain parameters and ephemeral ECDH public 797 key from the ServerKeyExchange message. (A possible reason for a 798 fatal handshake failure is that the client's capabilities for 799 handling elliptic curves and point formats are exceeded; cf. 800 Section 5.1.) 802 5.5. Certificate Request 804 When this message is sent: 806 This message is sent when requesting client authentication. 808 Meaning of this message: 810 The server uses this message to suggest acceptable client 811 authentication methods. 813 Structure of this message: 815 The TLS CertificateRequest message is extended as follows. 817 enum { 818 ecdsa_sign(64), rsa_fixed_ecdh(65), 819 ecdsa_fixed_ecdh(66), (255) 820 } ClientCertificateType; 822 ecdsa_sign, etc. Indicates that the server would like to use the 823 corresponding client authentication method specified in Section 3. 825 Actions of the sender: 827 The server decides which client authentication methods it would like 828 to use, and conveys this information to the client using the format 829 defined above. 831 Actions of the receiver: 833 The client determines whether it has a suitable certificate for use 834 with any of the requested methods and whether to proceed with client 835 authentication. 837 5.6. Client Certificate 839 When this message is sent: 841 This message is sent in response to a CertificateRequest when a 842 client has a suitable certificate and has decided to proceed with 843 client authentication. (Note that if the server has used a Supported 844 Point Formats Extension, a certificate can only be considered 845 suitable for use with the ECDSA_sign, RSA_fixed_ECDH, and 846 ECDSA_fixed_ECDH authentication methods if the public key point 847 specified in it respects the server's choice of point formats. If no 848 Supported Point Formats Extension has been used, a certificate can 849 only be considered suitable for use with these authentication methods 850 if the point is represented in uncompressed point format.) 852 Meaning of this message: 854 This message is used to authentically convey the client's static 855 public key to the server. The following table summarizes what client 856 certificate types are appropriate for the ECC-based client 857 authentication mechanisms described in Section 3. ECC public keys 858 must be encoded in certificates as described in Section 5.9. 860 NOTE: The client's Certificate message is capable of carrying a chain 861 of certificates. The restrictions mentioned in Table 4 apply only to 862 the client's certificate (first in the chain). 864 +------------------+------------------------------------------------+ 865 | Client | Client Certificate Type | 866 | Authentication | | 867 | Method | | 868 +------------------+------------------------------------------------+ 869 | ECDSA_sign | Certificate MUST contain an ECDSA-capable | 870 | | public key and be signed with ECDSA. | 871 | ECDSA_fixed_ECDH | Certificate MUST contain an ECDH-capable | 872 | | public key on the same elliptic curve as the | 873 | | server's long-term ECDH key. This certificate | 874 | | MUST be signed with ECDSA. | 875 | RSA_fixed_ECDH | Certificate MUST contain an ECDH-capable | 876 | | public key on the same elliptic curve as the | 877 | | server's long-term ECDH key. This certificate | 878 | | MUST be signed with RSA. | 879 +------------------+------------------------------------------------+ 881 Table 4: Client Certificate Types 883 Structure of this message: 885 Identical to the TLS client Certificate format. 887 Actions of the sender: 889 The client constructs an appropriate certificate chain, and conveys 890 it to the server in the Certificate message. 892 Actions of the receiver: 894 The TLS server validates the certificate chain, extracts the client's 895 public key, and checks that the key type is appropriate for the 896 client authentication method. 898 5.7. Client Key Exchange 900 When this message is sent: 902 This message is sent in all key exchange algorithms. If client 903 authentication with ECDSA_fixed_ECDH or RSA_fixed_ECDH is used, this 904 message is empty. Otherwise, it contains the client's ephemeral ECDH 905 public key. 907 Meaning of the message: 909 This message is used to convey ephemeral data relating to the key 910 exchange belonging to the client (such as its ephemeral ECDH public 911 key). 913 Structure of this message: 915 The TLS ClientKeyExchange message is extended as follows. 917 enum { implicit, explicit } PublicValueEncoding; 919 implicit, explicit: For ECC cipher suites, this indicates whether 920 the client's ECDH public key is in the client's certificate 921 ("implicit") or is provided, as an ephemeral ECDH public key, in 922 the ClientKeyExchange message ("explicit"). (This is "explicit" 923 in ECC cipher suites except when the client uses the 924 ECDSA_fixed_ECDH or RSA_fixed_ECDH client authentication 925 mechanism.) 927 struct { 928 select (PublicValueEncoding) { 929 case implicit: struct { }; 930 case explicit: ECPoint ecdh_Yc; 931 } ecdh_public; 932 } ClientECDiffieHellmanPublic; 933 ecdh_Yc: Contains the client's ephemeral ECDH public key as a byte 934 string ECPoint.point, which may represent an elliptic curve point 935 in uncompressed or compressed format. Here, the format MUST 936 conform to what the server has requested through a Supported Point 937 Formats Extension if this extension was used, and MUST be 938 uncompressed if this extension was not used. 940 struct { 941 select (KeyExchangeAlgorithm) { 942 case ec_diffie_hellman: ClientECDiffieHellmanPublic; 943 } exchange_keys; 944 } ClientKeyExchange; 946 Actions of the sender: 948 The client selects an ephemeral ECDH public key corresponding to the 949 parameters it received from the server according to the ECKAS-DH1 950 scheme from IEEE 1363. It conveys this information to the client in 951 the ClientKeyExchange message using the format defined above. 953 Actions of the receiver: 955 The server retrieves the client's ephemeral ECDH public key from the 956 ClientKeyExchange message and checks that it is on the same elliptic 957 curve as the server's ECDH key. 959 5.8. Certificate Verify 961 When this message is sent: 963 This message is sent when the client sends a client certificate 964 containing a public key usable for digital signatures, e.g., when the 965 client is authenticated using the ECDSA_sign mechanism. 967 Meaning of the message: 969 This message contains a signature that proves possession of the 970 private key corresponding to the public key in the client's 971 Certificate message. 973 Structure of this message: 975 The TLS CertificateVerify message and the underlying Signature type 976 are defined in the TLS base specifications, and the latter is 977 extended here in Section 5.4. For the ecdsa case, the signature 978 field in the CertificateVerify message contains an ECDSA signature 979 computed over handshake messages exchanged so far, exactly similar to 980 CertificateVerify with other signing algorithms: 982 CertificateVerify.signature.sha_hash 983 SHA(handshake_messages); 985 ECDSA signatures are computed as described in Section 5.10, and SHA 986 in the above template for sha_hash accordingly may denote a hash 987 algorithm other than SHA-1. As per ANSI X9.62, an ECDSA signature 988 consists of a pair of integers, r and s. The digitally-signed 989 element is encoded as an opaque vector <0..2^16-1>, the contents of 990 which are the DER encoding [CCITT.X690] corresponding to the 991 following ASN.1 notation [CCITT.X680]. 993 Ecdsa-Sig-Value ::= SEQUENCE { 994 r INTEGER, 995 s INTEGER 996 } 998 Actions of the sender: 1000 The client computes its signature over all handshake messages sent or 1001 received starting at client hello and up to but not including this 1002 message. It uses the private key corresponding to its certified 1003 public key to compute the signature, which is conveyed in the format 1004 defined above. 1006 Actions of the receiver: 1008 The server extracts the client's signature from the CertificateVerify 1009 message, and verifies the signature using the public key it received 1010 in the client's Certificate message. 1012 5.9. Elliptic Curve Certificates 1014 X.509 certificates containing ECC public keys or signed using ECDSA 1015 MUST comply with [RFC3279] or another RFC that replaces or extends 1016 it. Clients SHOULD use the elliptic curve domain parameters 1017 recommended in ANSI X9.62, FIPS 186-4, and SEC 2 [SECG-SEC2]. 1019 5.10. ECDH, ECDSA, and RSA Computations 1021 All ECDH calculations (including parameter and key generation as well 1022 as the shared secret calculation) are performed according to 1023 [IEEE.P1363.1998] using the ECKAS-DH1 scheme with the identity map as 1024 key derivation function (KDF), so that the premaster secret is the 1025 x-coordinate of the ECDH shared secret elliptic curve point 1026 represented as an octet string. Note that this octet string (Z in 1027 IEEE 1363 terminology) as output by FE2OSP, the Field Element to 1028 Octet String Conversion Primitive, has constant length for any given 1029 field; leading zeros found in this octet string MUST NOT be 1030 truncated. 1032 (Note that this use of the identity KDF is a technicality. The 1033 complete picture is that ECDH is employed with a non-trivial KDF 1034 because TLS does not directly use the premaster secret for anything 1035 other than for computing the master secret. In TLS 1.0 and 1.1, this 1036 means that the MD5- and SHA-1-based TLS PRF serves as a KDF; in TLS 1037 1.2 the KDF is determined by ciphersuite; it is conceivable that 1038 future TLS versions or new TLS extensions introduced in the future 1039 may vary this computation.) 1041 All ECDSA computations MUST be performed according to ANSI X9.62 or 1042 its successors. Data to be signed/verified is hashed, and the result 1043 run directly through the ECDSA algorithm with no additional hashing. 1044 The default hash function is SHA-1 [FIPS.180-2], and sha_size (see 1045 Section 5.4 and Section 5.8) is 20. However, an alternative hash 1046 function, such as one of the new SHA hash functions specified in FIPS 1047 180-2 [FIPS.180-2], may be used instead. 1049 RFC 4492 anticipated the standardization of a mechanism for 1050 specifying the required hash function in the certificate, perhaps in 1051 the parameters field of the subjectPublicKeyInfo. Such 1052 standardization never took place, and as a result, SHA-1 is used in 1053 TLS 1.1 and earlier. TLS 1.2 added a SignatureAndHashAlgorithm 1054 parameter to the DigitallySigned struct, thus allowing agility in 1055 choosing the signature hash. 1057 All RSA signatures must be generated and verified according to 1058 [PKCS1] block type 1. 1060 6. Cipher Suites 1062 The table below defines new ECC cipher suites that use the key 1063 exchange algorithms specified in Section 2. 1065 +---------------------------------------+----------------+ 1066 | CipherSuite | Identifier | 1067 +---------------------------------------+----------------+ 1068 | TLS_ECDHE_ECDSA_WITH_NULL_SHA | { 0xC0, 0x06 } | 1069 | TLS_ECDHE_ECDSA_WITH_RC4_128_SHA | { 0xC0, 0x07 } | 1070 | TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA | { 0xC0, 0x08 } | 1071 | TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA | { 0xC0, 0x09 } | 1072 | TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA | { 0xC0, 0x0A } | 1073 | | | 1074 | TLS_ECDHE_RSA_WITH_NULL_SHA | { 0xC0, 0x10 } | 1075 | TLS_ECDHE_RSA_WITH_RC4_128_SHA | { 0xC0, 0x11 } | 1076 | TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA | { 0xC0, 0x12 } | 1077 | TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA | { 0xC0, 0x13 } | 1078 | TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA | { 0xC0, 0x14 } | 1079 | | | 1080 | TLS_ECDH_anon_WITH_NULL_SHA | { 0xC0, 0x15 } | 1081 | TLS_ECDH_anon_WITH_RC4_128_SHA | { 0xC0, 0x16 } | 1082 | TLS_ECDH_anon_WITH_3DES_EDE_CBC_SHA | { 0xC0, 0x17 } | 1083 | TLS_ECDH_anon_WITH_AES_128_CBC_SHA | { 0xC0, 0x18 } | 1084 | TLS_ECDH_anon_WITH_AES_256_CBC_SHA | { 0xC0, 0x19 } | 1085 +---------------------------------------+----------------+ 1087 Table 5: TLS ECC cipher suites 1089 The key exchange method, cipher, and hash algorithm for each of these 1090 cipher suites are easily determined by examining the name. Ciphers 1091 (other than AES ciphers) and hash algorithms are defined in [RFC2246] 1092 and [RFC4346]. AES ciphers are defined in [RFC5246]. 1094 Server implementations SHOULD support all of the following cipher 1095 suites, and client implementations SHOULD support at least one of 1096 them: 1098 o TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 1099 o TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA 1100 o TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 1101 o TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 1103 7. Security Considerations 1105 Security issues are discussed throughout this memo. 1107 For TLS handshakes using ECC cipher suites, the security 1108 considerations in appendices D of all three TLS base documemts apply 1109 accordingly. 1111 Security discussions specific to ECC can be found in 1112 [IEEE.P1363.1998] and [ANSI.X9-62.2005]. One important issue that 1113 implementers and users must consider is elliptic curve selection. 1114 Guidance on selecting an appropriate elliptic curve size is given in 1115 Table 1. 1117 Beyond elliptic curve size, the main issue is elliptic curve 1118 structure. As a general principle, it is more conservative to use 1119 elliptic curves with as little algebraic structure as possible. 1120 Thus, random curves are more conservative than special curves such as 1121 Koblitz curves, and curves over F_p with p random are more 1122 conservative than curves over F_p with p of a special form (and 1123 curves over F_p with p random might be considered more conservative 1124 than curves over F_2^m as there is no choice between multiple fields 1125 of similar size for characteristic 2). Note, however, that algebraic 1126 structure can also lead to implementation efficiencies, and 1127 implementers and users may, therefore, need to balance conservatism 1128 against a need for efficiency. Concrete attacks are known against 1129 only very few special classes of curves, such as supersingular 1130 curves, and these classes are excluded from the ECC standards that 1131 this document references [IEEE.P1363.1998], [ANSI.X9-62.2005]. 1133 Another issue is the potential for catastrophic failures when a 1134 single elliptic curve is widely used. In this case, an attack on the 1135 elliptic curve might result in the compromise of a large number of 1136 keys. Again, this concern may need to be balanced against efficiency 1137 and interoperability improvements associated with widely-used curves. 1138 Substantial additional information on elliptic curve choice can be 1139 found in [IEEE.P1363.1998], [ANSI.X9-62.2005], and [FIPS.186-4]. 1141 All of the key exchange algorithms defined in this document provide 1142 forward secrecy. Some of the deprecated key exchange algorithms do 1143 not. 1145 8. IANA Considerations 1147 [RFC4492], the predecessor of this document has already defined the 1148 IANA registries for the following: 1150 o NamedCurve Section 5.1 1151 o ECPointFormat Section 5.1 1152 o ECCurveType Section 5.4 1154 For each name space, this document defines the initial value 1155 assignments and defines a range of 256 values (NamedCurve) or eight 1156 values (ECPointFormat and ECCurveType) reserved for Private Use. Any 1157 additional assignments require IETF Consensus action. 1159 9. Acknowledgements 1161 Most of the text is this document is taken from [RFC4492], the 1162 predecessor of this document. The authors of that document were: 1164 o Simon Blake-Wilson 1165 o Nelson Bolyard 1166 o Vipul Gupta 1167 o Chris Hawk 1168 o Bodo Moeller 1170 In the predecessor document, the authors acknowledged the 1171 contributions of Bill Anderson and Tim Dierks. 1173 10. Version History for This Draft 1175 NOTE TO RFC EDITOR: PLEASE REMOVE THIS SECTION 1177 Changes from draft-ietf-tls-rfc4492bis-01 to draft-nir-tls- 1178 rfc4492bis-03: 1180 o Removed unused curves. 1181 o Removed unused point formats (all but uncompressed) 1183 Changes from draft-nir-tls-rfc4492bis-00 and draft-ietf-tls- 1184 rfc4492bis-00 to draft-nir-tls-rfc4492bis-01: 1186 o Merged errata 1187 o Removed ECDH_RSA and ECDH_ECDSA 1189 Changes from RFC 4492 to draft-nir-tls-rfc4492bis-00: 1191 o Added TLS 1.2 to references. 1192 o Moved RFC 4492 authors to acknowledgements. 1193 o Removed list of required reading for ECC. 1195 11. References 1197 11.1. Normative References 1199 [ANSI.X9-62.2005] 1200 American National Standards Institute, "Public Key 1201 Cryptography for the Financial Services Industry, The 1202 Elliptic Curve Digital Signature Algorithm (ECDSA)", ANSI 1203 X9.62, 2005. 1205 [CCITT.X680] 1206 International Telephone and Telegraph Consultative 1207 Committee, "Abstract Syntax Notation One (ASN.1): 1208 Specification of basic notation", CCITT Recommendation 1209 X.680, July 2002. 1211 [CCITT.X690] 1212 International Telephone and Telegraph Consultative 1213 Committee, "ASN.1 encoding rules: Specification of basic 1214 encoding Rules (BER), Canonical encoding rules (CER) and 1215 Distinguished encoding rules (DER)", CCITT Recommendation 1216 X.690, July 2002. 1218 [FIPS.186-4] 1219 National Institute of Standards and Technology, "Digital 1220 Signature Standard", FIPS PUB 186-4, 2013, 1221 . 1224 [PKCS1] RSA Laboratories, "RSA Encryption Standard, Version 1.5", 1225 PKCS 1, November 1993. 1227 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1228 Requirement Levels", BCP 14, RFC 2119, March 1997. 1230 [RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", 1231 RFC 2246, January 1999. 1233 [RFC3279] Bassham, L., Polk, W., and R. Housley, "Algorithms and 1234 Identifiers for the Internet X.509 Public Key 1235 Infrastructure Certificate and Certificate Revocation List 1236 (CRL) Profile", RFC 3279, April 2002. 1238 [RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security 1239 (TLS) Protocol Version 1.1", RFC 4346, April 2006. 1241 [RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., 1242 and T. Wright, "Transport Layer Security (TLS) 1243 Extensions", RFC 4366, April 2006. 1245 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 1246 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 1248 [SECG-SEC2] 1249 CECG, "Recommended Elliptic Curve Domain Parameters", SEC 1250 2, 2000. 1252 11.2. Informative References 1254 [FIPS.180-2] 1255 National Institute of Standards and Technology, "Secure 1256 Hash Standard", FIPS PUB 180-2, August 2002, 1257 . 1260 [I-D.ietf-tls-tls13] 1261 Dierks, T. and E. Rescorla, "The Transport Layer Security 1262 (TLS) Protocol Version 1.3", draft-ietf-tls-tls13-02 (work 1263 in progress), July 2014. 1265 [IEEE.P1363.1998] 1266 Institute of Electrical and Electronics Engineers, 1267 "Standard Specifications for Public Key Cryptography", 1268 IEEE Draft P1363, 1998. 1270 [Lenstra_Verheul] 1271 Lenstra, A. and E. Verheul, "Selecting Cryptographic Key 1272 Sizes", Journal of Cryptology 14 (2001) 255-293, 2001. 1274 [RFC4492] Blake-Wilson, S., Bolyard, N., Gupta, V., Hawk, C., and B. 1275 Moeller, "Elliptic Curve Cryptography (ECC) Cipher Suites 1276 for Transport Layer Security (TLS)", RFC 4492, May 2006. 1278 Appendix A. Equivalent Curves (Informative) 1280 All of the NIST curves [FIPS.186-4] and several of the ANSI curves 1281 [ANSI.X9-62.2005] are equivalent to curves listed in Section 5.1.1. 1282 In the following table, multiple names in one row represent aliases 1283 for the same curve. 1285 Curve names chosen by different standards organizations 1287 +-----------+------------+------------+ 1288 | SECG | ANSI X9.62 | NIST | 1289 +-----------+------------+------------+ 1290 | sect163k1 | | NIST K-163 | 1291 | sect163r1 | | | 1292 | sect163r2 | | NIST B-163 | 1293 | sect193r1 | | | 1294 | sect193r2 | | | 1295 | sect233k1 | | NIST K-233 | 1296 | sect233r1 | | NIST B-233 | 1297 | sect239k1 | | | 1298 | sect283k1 | | NIST K-283 | 1299 | sect283r1 | | NIST B-283 | 1300 | sect409k1 | | NIST K-409 | 1301 | sect409r1 | | NIST B-409 | 1302 | sect571k1 | | NIST K-571 | 1303 | sect571r1 | | NIST B-571 | 1304 | secp160k1 | | | 1305 | secp160r1 | | | 1306 | secp160r2 | | | 1307 | secp192k1 | | | 1308 | secp192r1 | prime192v1 | NIST P-192 | 1309 | secp224k1 | | | 1310 | secp224r1 | | NIST P-224 | 1311 | secp256k1 | | | 1312 | secp256r1 | prime256v1 | NIST P-256 | 1313 | secp384r1 | | NIST P-384 | 1314 | secp521r1 | | NIST P-521 | 1315 +-----------+------------+------------+ 1317 Table 6: Equivalent curves defined by SECG, ANSI, and NIST 1319 Appendix B. Differences from RFC 4492 1321 o Added TLS 1.2 1322 o Merged Errata 1323 o Removed the ECDH key exchange algorithms: ECDH_RSA and ECDH_ECDSA 1324 o Deprecated a bunch of ciphersuites: 1326 TLS_ECDH_ECDSA_WITH_NULL_SHA 1327 TLS_ECDH_ECDSA_WITH_RC4_128_SHA 1328 TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA 1329 TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA 1330 TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA 1331 TLS_ECDH_RSA_WITH_NULL_SHA 1332 TLS_ECDH_RSA_WITH_RC4_128_SHA 1333 TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA 1334 TLS_ECDH_RSA_WITH_AES_128_CBC_SHA 1335 TLS_ECDH_RSA_WITH_AES_256_CBC_SHA 1337 Removed unused curves and all but the uncompressed point format. 1339 Author's Address 1341 Yoav Nir 1342 Check Point Software Technologies Ltd. 1343 5 Hasolelim st. 1344 Tel Aviv 6789735 1345 Israel 1347 Email: ynir.ietf@gmail.com