rfc5246 The Transport Layer Security (TLS) Protocol Version 1.2

The Transport Layer Security (TLS) Protocol
                              Version 1.2
Network Working Group                                          T. Dierks
Request for Comments: 5246                                   Independent
Obsoletes: 3268, 4346, 4366                                  E. Rescorla
Updates: 4492                                                 RTFM, Inc.
Category: Standards Track                                    August 2008

【外部リンク】
https://tools.ietf.org/html/rfc5246
Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   This document specifies Version 1.2 of the Transport Layer Security
   (TLS) protocol.  The TLS protocol provides communications security
   over the Internet.  The protocol allows client/server applications to
   communicate in a way that is designed to prevent eavesdropping,
   tampering, or message forgery.
Table of Contents

   1. Introduction ....................................................4
      1.1. Requirements Terminology ...................................5
      1.2. Major Differences from TLS 1.1 .............................5
   2. Goals ...........................................................6
   3. Goals of This Document ..........................................7
   4. Presentation Language ...........................................7
      4.1. Basic Block Size ...........................................7
      4.2. Miscellaneous ..............................................8
      4.3. Vectors ....................................................8
      4.4. Numbers ....................................................9
      4.5. Enumerateds ................................................9
      4.6. Constructed Types .........................................10
           4.6.1. Variants ...........................................10
      4.7. Cryptographic Attributes ..................................12
      4.8. Constants .................................................14
   5. HMAC and the Pseudorandom Function .............................14
   6. The TLS Record Protocol ........................................15
      6.1. Connection States .........................................16
      6.2. Record Layer ..............................................19
           6.2.1. Fragmentation ......................................19



Dierks & Rescorla           Standards Track                     [Page 1]

RFC 5246                          TLS                        August 2008


           6.2.2. Record Compression and Decompression ...............20
           6.2.3. Record Payload Protection ..........................21
                  6.2.3.1. Null or Standard Stream Cipher ............22
                  6.2.3.2. CBC Block Cipher ..........................22
                  6.2.3.3. AEAD Ciphers ..............................24
      6.3. Key Calculation ...........................................25
   7. The TLS Handshaking Protocols ..................................26
      7.1. Change Cipher Spec Protocol ...............................27
      7.2. Alert Protocol ............................................28
           7.2.1. Closure Alerts .....................................29
           7.2.2. Error Alerts .......................................30
      7.3. Handshake Protocol Overview ...............................33
      7.4. Handshake Protocol ........................................37
           7.4.1. Hello Messages .....................................38
                  7.4.1.1. Hello Request .............................38
                  7.4.1.2. Client Hello ..............................39
                  7.4.1.3. Server Hello ..............................42
                  7.4.1.4. Hello Extensions ..........................44
                           7.4.1.4.1. Signature Algorithms ...........45
           7.4.2. Server Certificate .................................47
           7.4.3. Server Key Exchange Message ........................50
           7.4.4. Certificate Request ................................53
           7.4.5. Server Hello Done ..................................55
           7.4.6. Client Certificate .................................55
           7.4.7. Client Key Exchange Message ........................57
                  7.4.7.1. RSA-Encrypted Premaster Secret Message ....58
                  7.4.7.2. Client Diffie-Hellman Public Value ........61
           7.4.8. Certificate Verify .................................62
           7.4.9. Finished ...........................................63
   8. Cryptographic Computations .....................................64
      8.1. Computing the Master Secret ...............................64
           8.1.1. RSA ................................................65
           8.1.2. Diffie-Hellman .....................................65
   9. Mandatory Cipher Suites ........................................65
   10. Application Data Protocol .....................................65
   11. Security Considerations .......................................65
   12. IANA Considerations ...........................................65
   Appendix A. Protocol Data Structures and Constant Values ..........68
      A.1. Record Layer ..............................................68
      A.2. Change Cipher Specs Message ...............................69
      A.3. Alert Messages ............................................69
      A.4. Handshake Protocol ........................................70
           A.4.1. Hello Messages .....................................71
           A.4.2. Server Authentication and Key Exchange Messages ....72
           A.4.3. Client Authentication and Key Exchange Messages ....74
           A.4.4. Handshake Finalization Message .....................74
      A.5. The Cipher Suite ..........................................75
      A.6. The Security Parameters ...................................77



Dierks & Rescorla           Standards Track                     [Page 2]

RFC 5246                          TLS                        August 2008


      A.7. Changes to RFC 4492 .......................................78
   Appendix B. Glossary ..............................................78
   Appendix C. Cipher Suite Definitions ..............................83
   Appendix D. Implementation Notes ..................................85
      D.1. Random Number Generation and Seeding ......................85
      D.2. Certificates and Authentication ...........................85
      D.3. Cipher Suites .............................................85
      D.4. Implementation Pitfalls ...................................85
   Appendix E. Backward Compatibility ................................87
      E.1. Compatibility with TLS 1.0/1.1 and SSL 3.0 ................87
      E.2. Compatibility with SSL 2.0 ................................88
      E.3. Avoiding Man-in-the-Middle Version Rollback ...............90
   Appendix F. Security Analysis .....................................91
      F.1. Handshake Protocol ........................................91
           F.1.1. Authentication and Key Exchange ....................91
                  F.1.1.1. Anonymous Key Exchange ....................91
                  F.1.1.2. RSA Key Exchange and Authentication .......92
                  F.1.1.3. Diffie-Hellman Key Exchange with
                           Authentication ............................92
           F.1.2. Version Rollback Attacks ...........................93
           F.1.3. Detecting Attacks Against the Handshake Protocol ...94
           F.1.4. Resuming Sessions ..................................94
      F.2. Protecting Application Data ...............................94
      F.3. Explicit IVs ..............................................95
      F.4. Security of Composite Cipher Modes ........................95
      F.5. Denial of Service .........................................96
      F.6. Final Notes ...............................................96
   Normative References ..............................................97
   Informative References ............................................98
   Working Group Information ........................................101
   Contributors .....................................................101