rfc2759.txt

RFC 的详细文档！

   NtPasswordHashEncryptedWithBlock(
   IN  16-octet PasswordHash,
   IN  16-octet Block,
   OUT 16-octet Cypher )
   {
      DesEncrypt( 1st 8-octets PasswordHash,
                  1st 7-octets Block,
                  giving 1st 8-octets Cypher )

      DesEncrypt( 2nd 8-octets PasswordHash,
                  2nd 7-octets Block,
                  giving 2nd 8-octets Cypher )
   }

9.  Examples

   The following sections include protocol negotiation and hash
   generation examples.

9.1.  Negotiation Examples

   Here are some examples of typical negotiations.  The peer is on the
   left and the authenticator is on the right.

   The packet sequence ID is incremented on each authentication retry
   response and on the change password response.  All cases where the
   packet sequence ID is updated are noted below.

   Response retry is never allowed after Change Password.  Change
   Password may occur after response retry.





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9.1.1.  Successful authentication

                         <- Authenticator Challenge
       Peer Response/Challenge ->
                         <- Success/Authenticator Response

   (Authenticator Response verification succeeds, call continues)

9.1.2.  Authenticator authentication failure

                         <- Authenticator Challenge
       Peer Response/Challenge ->
                         <- Success/Authenticator Response

   (Authenticator Response verification fails, peer disconnects)

9.1.3.  Failed authentication with no retry allowed

                         <- Authenticator Challenge
       Peer Response/Challenge ->
                         <- Failure (E=691 R=0)

   (Authenticator disconnects)

9.1.4.  Successful authentication after retry

                         <- Authenticator Challenge
       Peer Response/Challenge ->
                         <- Failure (E=691 R=1), disable short timeout
       Response (++ID) to challenge in failure message ->
                         <- Success/Authenticator Response

   (Authenticator Response verification succeeds, call continues)

9.1.5.  Failed hack attack with 3 attempts allowed

                         <- Authenticator Challenge
       Peer Response/Challenge ->
                         <- Failure (E=691 R=1), disable short timeout
       Response (++ID) to challenge in Failure message ->
                         <- Failure (E=691 R=1), disable short timeout
       Response (++ID) to challenge in Failure message ->
                         <- Failure (E=691 R=0)








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9.1.6.  Successful authentication with password change

                         <- Authenticator Challenge
       Peer Response/Challenge ->
                         <- Failure (E=648 R=0 V=3), disable short
   timeout
       ChangePassword (++ID) to challenge in Failure message ->
                         <- Success/Authenticator Response

   (Authenticator Response verification succeeds, call continues)

9.1.7.  Successful authentication with retry and password change

                         <- Authenticator Challenge
       Peer Response/Challenge ->
                         <- Failure (E=691 R=1), disable short timeout
       Response (++ID) to first challenge+23 ->
                         <- Failure (E=648 R=0 V=2), disable short
   timeout
       ChangePassword (++ID) to first challenge+23 ->
                         <- Success/Authenticator Response

   (Authenticator Response verification succeeds, call continues)

9.2.  Hash Example

   Intermediate values for user name "User" and password "clientPass".
   All numeric values are hexadecimal.

0-to-256-char UserName:
55 73 65 72

0-to-256-unicode-char Password:
63 00 6C 00 69 00 65 00 6E 00 74 00 50 00 61 00 73 00 73 00

16-octet AuthenticatorChallenge:
5B 5D 7C 7D 7B 3F 2F 3E 3C 2C 60 21 32 26 26 28

16-octet PeerChallenge:
21 40 23 24 25 5E 26 2A 28 29 5F 2B 3A 33 7C 7E

8-octet Challenge:
D0 2E 43 86 BC E9 12 26

16-octet PasswordHash:
44 EB BA 8D 53 12 B8 D6 11 47 44 11 F5 69 89 AE





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24 octet NT-Response:
82 30 9E CD 8D 70 8B 5E A0 8F AA 39 81 CD 83 54 42 33 11 4A 3D 85 D6 DF

16-octet PasswordHashHash:
41 C0 0C 58 4B D2 D9 1C 40 17 A2 A1 2F A5 9F 3F

42-octet AuthenticatorResponse:
"S=407A5589115FD0D6209F510FE9C04566932CDA56"

9.3.  Example of DES Key Generation

   DES uses 56-bit keys, expanded to 64 bits by the insertion of parity
   bits.  After the parity of the key has been fixed, every eighth bit
   is a parity bit and the number of bits that are set (1) in each octet
   is odd; i.e., odd parity.  Note that many DES engines do not check
   parity, however, simply stripping the parity bits.  The following
   example illustrates the values resulting from the use of the password
   "MyPw" to generate a pair of DES keys (e.g., for use in the
   NtPasswordHashEncryptedWithBlock() described in section 8.13).

   0-to-256-unicode-char Password:
   4D 79 50 77

   16-octet PasswordHash:
   FC 15 6A F7 ED CD 6C 0E DD E3 33 7D 42 7F 4E AC

   First "raw" DES key (initial 7 octets of password hash):
   FC 15 6A F7 ED CD 6C

   First parity-corrected DES key (eight octets):
   FD 0B 5B 5E 7F 6E 34 D9

   Second "raw" DES key (second 7 octets of password hash)
   0E DD E3 33 7D 42 7F

   Second parity-corrected DES key (eight octets):
   0E 6E 79 67 37 EA 08 FE

10.  Security Considerations

   As an implementation detail, the authenticator SHOULD limit the
   number of password retries allowed to make brute-force password
   guessing attacks more difficult.








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11.  References

   [1]  Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51, RFC
        1661, July 1994.

   [2]  Simpson, W., "PPP Challenge Handshake Authentication Protocol
        (CHAP)", RFC 1994, August 1996.

   [3]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [4]  "Data Encryption Standard (DES)", Federal Information Processing
        Standard Publication 46-2, National Institute of Standards and
        Technology, December 1993.

   [5]  Rivest, R., "MD4 Message Digest Algorithm", RFC 1320, April
        1992.

   [6]  RC4 is a proprietary encryption algorithm available under
        license from RSA Data Security Inc.  For licensing information,
        contact:

             RSA Data Security, Inc.
             100 Marine Parkway
             Redwood City, CA 94065-1031

   [7]  Eastlake, D., Crocker, S. and J. Schiller, "Randomness
        Recommendations for Security", RFC 1750, December 1994.

   [8]  "The Unicode Standard, Version 2.0", The Unicode Consortium,
        Addison-Wesley, 1996. ISBN 0-201-48345-9.

   [9]  Zorn, G. and Cobb, S., "Microsoft PPP CHAP Extensions", RFC
        2433, October 1998.

   [10] "DES Modes of Operation", Federal Information Processing
        Standards Publication 81, National Institute of Standards and
        Technology, December 1980.

   [11] "Secure Hash Standard", Federal Information Processing Standards
        Publication 180-1, National Institute of Standards and
        Technology, April 1995.

   [12] Zorn, G., "PPP LCP Internationalization Configuration Option",
        RFC 2484, January 1999.






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12.  Acknowledgements

   Thanks (in no particular order) to Bruce Johnson, Tony Bell, Paul
   Leach, Terence Spies, Dan Simon, Narendra Gidwani, Gurdeep Singh
   Pall, Jody Terrill, Brad Robel-Forrest, and Joe Davies for useful
   suggestions and feedback.

13.  Author's Address

   Questions about this memo can also be directed to:

   Glen Zorn
   Microsoft Corporation
   One Microsoft Way
   Redmond, Washington 98052

   Phone: [phone]
   Fax:   [phone]
   EMail: [e-mail]
































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14.  Full Copyright Statement

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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