RE: [ipcdn] FW: DISCUSS: draft-ietf-ipcdn-bpiplus-mib-14

["Eduardo Cardona" <[e-mail]>]

Bert, I am not sure if this is just perception from the parser output:
Below is a similar public key pair that indicates the offsets line by
line 
Ofsset 135 (zero  based) indicates the start of the public exponent (5
bytes)
Offset 140 indicates the offset of byte 141



Here is a 140 octets PKCS#1 public key pair

Off  
  0      30 81 89
  3      02 81 81 
  6               00 cf 32 d2 0b 31 d5 47 f9 73 98 8a 83 62 e1 fb
 22               dc e6 3b 0b 4b b8 d6 3b 35 31 5d dc 7a 72 89 fe
 38               e9 18 20 c7 83 7b 76 d7 75 36 91 72 f6 17 8f 5a
 54               59 68 28 87 0d 9b 25 88 52 7b cb a2 52 10 26 89
 70               69 4f 0d d1 d9 2d 71 aa 03 35 e2 81 5d b0 31 8b
 86               4c 3d e9 0a df b4 8c e4 99 7f d1 47 86 5b 9e 3d 
102               07 c3 a8 58 f3 2f f2 d3 09 a6 e3 e5 4c 53 23 44 
118               46 6c 6b 03 ae 90 76 38 60 de 23 02 f9 c0 3b e4 
134               ed
135      02 03 01 00 01
140

Bytes size = 3 + 3 + 129 + 5 = 140

And the output from for the equivalent binary file 
from openssl asn1parse command:

    0:d=0  hl=3 l= 137 cons: SEQUENCE
    3:d=1  hl=3 l= 129 prim: INTEGER           
                             :CF32D20B31D547F973988A8362E1FBDC
                              E63B0B4BB8D63B35315DDC7A7289FEE9
                              1820C7837B76D775369172F6178F5A59
                              6828870D9B2588527BCBA25210268969
                              4F0DD1D92D71AA0335E2815DB0318B4C
                              3DE90ADFB48CE4997FD147865B9E3D07
                              C3A858F32FF2D309A6E3E54C53234446
                              6C6B03AE90763860DE2302F9C03BE4ED
  135:d=1  hl=2 l=   3 prim: INTEGER           :010001



>
>   I do not believe that a five (or even ten) specific sizes can be
>   chosen that accommodate all valid RSA public keys.

 DOCSIS uses a subset of moduli values that matches the sizes described
by the MIB object
 After the explanations above, is this still an issue?


> Can we get an strong
>   integrity algorithm specified?  If not, the last few paragraphs of
>   of the Security Considerations need to be made much more forceful.

I can't disclosure current spec work around DOCSIS protocols in IPCDN
who includes 
persons probably not under CableLabs NDAs. 

Perhaps a reference to section 7.7 of BPI+ specification (available at
http://www.cablelabs.com/specifications/archives/SP-BPI+_I10-030730.pdf
)
will that be sufice by indicate the Protocol extensibility for strong
algorithms 
which are highly recommended. 



7.7 Supporting Alternative Algorithms
The current BPI+ specification requires the use of 56-bit DES for
encrypting packet data, two-key
triple DES for encrypting traffic encryption keys, 1024-bit [RSA] for
encrypting Authorization keys,
and 1024-to-2048-bit [RSA] for signing BPI+ X.509 certificates. The
choice of key lengths and
algorithms, while appropriate for current threat models and hardware
capabilities, may be
inappropriate in the future.
For example, it is generally agreed that DES is approaching the end of
its practical usefulness as the
industry standard for symmetric encryption. NIST is currently overseeing
the development and
adoption of a new standard encryption algorithm, commonly referred to as
the Advanced Encryption
Standard, or AES. Given the nature of the security services BPI+ is
being asked to support (basic
privacy at a level better than or equal to that possible over dedicated
wires, and conditional access to
RF data transport services) as well as the protocol's flexible key
management policy (i.e., setting of
key lifetimes), DOCSIS-based service providers will be justified in the
continued reliance on DES for,
at least, the next five years. Nevertheless, at some future date, DOCSIS
Cable modems will need to
adopt a stronger traffic encryption algorithm, possibly AES.
Adopting a new algorithm for packet data encryption will not require a
redesign of BPI+. The
protocol's consistent use of Type/Length/Value encoding of BPKM
attributes, MAC Header Extended
Header elements, and security capabilities selection in the
authorization exchange guarantee BPI+'s
extensibility. In fact, changes in any of BPI+'s cryptographic
algorithms, or associated key lengths,
will have no impact on the overall structure and operation of the
protocol. 
-----Original Message-----
From: Wijnen, Bert (Bert) [mailto:[e-mail]] 
Sent: Thursday, September 23, 2004 6:12 AM
To: Ipcdn (E-mail)
Subject: [ipcdn] FW: DISCUSS: draft-ietf-ipcdn-bpiplus-mib-14


>  COMMENT
>
>   Please delete the second paragraph of the Abstract prior to
publication
>   as an RFC.
>
>   In the Abstract: s/DOCSIS1.1/DOCSIS 1.1/

OK

Thanks

Eduardo


I am forwarding IESG comments as I receive them.

Answers are fine. Pls do not yet submit a changed document untill we get
ALL the IESG comments. Should be around Tuesday next week.

Bert

-----Original Message-----
From: Russ Housley [mailto:[e-mail]]
Sent: Wednesday, September 22, 2004 21:51
To: [e-mail]
Subject: DISCUSS: draft-ietf-ipcdn-bpiplus-mib-14


Management Information Base for DOCSIS Cable Modems and Cable Modem
Termination Systems for Baseline Privacy Plus (Proposed Standard)

DISCUSS

   The definition of docsBpi2CmPublicKey begins:
   :
   :  docsBpi2CmPublicKey     OBJECT-TYPE
   :       SYNTAX             OCTET STRING (SIZE (74|106|140|204|270))
   :
  The selection of these few octet string sizes is inappropriate.
   PKCS #1 encoding of an RSA public key is a SEQUENCE of two
   INTEGERs.  One example of an acceptable RSA public key that
   cannot be accommodated by this definition follows.  It is 139
   octets.

        0 30  137: SEQUENCE {
        3 02  129:   INTEGER
                 :     00 DD D8 49 85 DD 76 BE 9C 64 D2 6A 0C B3 3A 14
                 :     0B 37 A5 60 97 90 40 3D C0 C6 9C 01 FB D0 6F B6
                 :     49 56 E5 1A 44 F7 C7 1D 23 4C 91 A2 6F BE F7 9A
                 :     D0 5F F0 88 9A 01 A2 0A 20 78 22 45 1A 9D 77 8F
                 :     CA 14 3E 75 44 3C D6 67 16 21 E5 42 B5 EC BF 62
                 :     6C 09 0E 4D D9 79 D0 55 82 5C 9C FD B1 B9 B6 A6
                 :     5B 42 83 FA 90 1E 74 3F 5C 1C 1F D8 73 40 94 3C
                 :     9A 9F 2A 04 FE ED 8C 69 C3 0E 10 A6 3B 0B A7 A4
                 :     CD
      135 02    3:   INTEGER 65537
                 :   }

   I do not believe that a five (or even ten) specific sizes can be
   chosen that accommodate all valid RSA public keys.

   The definition of docsBpi2CmtsAuthCmPublicKey has the same problem.

   The definition of docsBpi2CmTEKDataEncryptAlg begins:
   :
   :  docsBpi2CmTEKDataEncryptAlg   OBJECT-TYPE
   :       SYNTAX         INTEGER {
   :                              none(0),
   :                              des56CbcMode(1),
   :                              des40CbcMode(2)
   :                              }
   :
   And, the definition of docsBpi2CmTEKDataAuthentAlg begins:
   :
   : docsBpi2CmTEKDataAuthentAlg   OBJECT-TYPE
   :      SYNTAX         INTEGER {
   :                             none(0)
   :                             }
   :
   These same values are also used in the
docsBpi2CmCryptoSuiteDataEncryptAlg,
   docsBpi2CmCryptoSuiteDataAuthentAlg, docsBpi2CmtsTEKDataEncryptAlg,
   docsBpi2CmtsTEKDataAuthentAlg, docsBpi2CmtsIpMulticastDataEncryptAlg,
   and docsBpi2CmtsIpMulticastDataAuthentAlg definitions.

   None of the encryption algorithm choices is a strong encryption
   algorithm.  Also, the encryption algorithm choice do not
   provide integrity, so they ought to be used with an integrity
   algorithm, but none are specified.  Can we get a strong
   encryption algorithm added to the list?  Can we get an strong
   integrity algorithm specified?  If not, the last few paragraphs of
   of the Security Considerations need to be made much more forceful.

   COMMENT

   Please delete the second paragraph of the Abstract prior to
publication
   as an RFC.

   In the Abstract: s/DOCSIS1.1/DOCSIS 1.1/


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