Description: The Enterasys Networks MIB module for configuring rapid
   rekeying on SNMPv1-only platforms.

   This MIB includes encrypted variants of selected objects
   from the Enterasys 802.1x Rapid Rekeying MIB.

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                             N O T I C E

        Use of this MIB in any product requires the approval
        of the Office of the CTO, Enterasys Networks, Inc.  
        Permission to use this MIB will not be granted for 
        products in which SNMPv3 is now, or will soon be,
        implemented.  Permission to use this MIB in products
        that are never scheduled to implement SNMPv3 will be 
        granted on a case-by-case basis, depending on what 
        other suitable, secure means of configuration are
        available in the product.

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   The following is a discussion of the encoding/decoding and
   encryption/decryption methods that must be used to extract
   data from an encrypted OCTET STRING.  (These methods are the
   same as for the Enterasys Networks encrypted RADIUS Client
   MIB.)
    
   The encryption/decryption methods make use of an agreed-upon
   Secret and an Authenticator shared between the SNMP network
   management system and the entity that implements the MIB.

   The encryption/decryption algorithm, as presented herein, is
   taken from the RADIUS protocol, and is the method specified
   for encryption of Tunnel-Password Attributes in RFC 2868.

   To permit plug-and-play remote installation, configuration,
   and management of the device, the device will algorithmically
   derive the initial shared secret and the initial authenticator.

   For security reasons, the network manager should change the
   authenticator portion of the management encryption key after
   initial configuration.  The methods available for doing this
   are implementation-specific and subject to change.  (On the
   RoamAbout AccessPoint 2000, the encrypted RADIUS client MIB
   contains an authenticator object used for both that MIB and
   this one.)

   All read-write and write-only access objects except the table
   index are encoded into fields in an OCTET STRING.

   Octet String

   Before encryption, the 'native' objects must be encoded into
   a formatted Octet String.  After decryption, the Octet String
   must be decoded to obtain the 'native' objects.

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|     Type      |    Length     |   Salt                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   String ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      
       Type
  
          The data type of the non-encrypted 'native' data:

          1 = Integer32
          2 = OCTET STRING
    
       Length

          The length in octets of the native object sub-field of
          the Octet String, exclusive of any optional padding.
          Note that the Integrity Check sub-fields (CRC, OID-tail,
          Time Stamp, Source IP Address) are not included in this
          length value, but since the IC sub-fields are always
          present and are of fixed length, there is no impediment
          to proper packet parsing.
          
       Salt

          The Salt field is two octets in length and is used to
          ensure the uniqueness of the encryption key used to
          encrypt each object.

          The most significant bit (leftmost) of the Salt field
          MUST be set (1).  The contents of each Salt field in a
          given SNMP packet must be unique.
    
       String

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  CRC (4 bytes)                                                |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  OID-tail (4 bytes)                                           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Time Stamp (4 bytes)                                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Source IP Address (4 bytes)                                  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Object/Padding ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      
          The plain-text String field consists of six logical
          sub-fields: the CRC, OID-tail, Time Stamp, Source IP
          address and native Object sub-fields (all of which are
          required), and the optional Padding sub-field.  The
          String field MUST be treated as a counted-string of
          undistinguished octets, and not as a standard
          C/UNIX-style null-terminated, printable ASCII string.
    
          CRC Sub-field

            The CRC sub-field contains a 32-bit CRC (CRC-32)
            calculated over the following concatentated sub-fields
            of the String: the OID-tail, Time Stamp, Source IP
            Address and unpadded native Object fields.  The CRC
            sub-field acts as an integrity check on the decrypted
            data.
    
          OID-tail Sub-field
    
            The OID-tail sub-field contains the least significant
            four octets of the Object ID of the varbind.  This
            field is included as an integrity check on the OID of
            the varbind.
    
          Time Stamp Sub-field
    
            The Time Stamp sub-field contains a 32-bit unsigned
            integer value representing the time the encrypted
            message was assembled.  This field acts as an
            integrity check by facilitating the disposal of stale
            or replayed messages. The time window of acceptance is
            implementation dependant, and may be the subject of
            local (i.e. managed entity) policy configuration.  The
            Time Stamp is relative time, in units of seconds,
            referenced to the sysUpTime object of the managed
            entity.
    
          Source IP Address Sub-field
    
            The Source IP Address sub-field contains an unsigned
            32-bit representation of the IPv4 address of the
            source of the encrypted message.  This is an added
            check to allow verification of the source of the
            varbind.

          The CRC, OID-tail, Time Stamp, and Source IP Address
          sub-fields are collectively hereinafter refered to as
          the Integrity Check (IC) sub-fields.
    
          Object/Padding Sub-field

            Object 
              The Object sub-field contains the actual or native
              object data followed by padding, if necessary.
    
            Padding
              If the combined length (in octets) of the
              non-encrypted CRC, OID-tail, Time Stamp, Source IP
              Address, and native Object sub-fields is not an even
              multiple of 16, then the Padding sub-field MUST be
              present.  If it is present, the length of the
              Padding sub-field is variable, between 1 and 15
              octets.  The value of the pad octets SHOULD be zero.
    
       Encrypting/Decrypting the String Field

          The entire String field MUST be encrypted as follows,
          prior to transmission:
    
          Construct a plain-text version of the String field by
          concatenating the CRC, OID-tail, Time Stamp, Source IP
          address, and native Object sub-fields.  If necessary,
          pad the resulting string until its length (in octets)
          is an even multiple of 16.  It is recommended that zero
          octets (0x00) be used for padding.  Call this plain-text
          P.

             Shared Secret

                The shared secret is formed from the MAC
                (hardware) address of the primary management
                interface of the managed device (containing the
                RADIUS Client).  The MAC address is represented
                as up-cased, dashed-ASCII, e.g. 08-00-2B-11-22-33.
    
            Authenticator
    
                The 128-bit authenticator is a pre-defined
                constant.  The default value of the authenticator
                is an Enterasys Networks trade secret.  This value
                is settable and the user is advised to change it
                from the default value after initial configuration
                of the system.  Contact the MIB author for
                additional information on the default value.
    
          Call the shared secret S, the [pseudo-random] 128-bit 
          Authenticator R, and the contents of the Salt field A.  
          Break P into 16 octet chunks p(1), p(2)...p(i), 
          where i = len(P)/16.  Call the cipher-text blocks 
          c(1), c(2)...c(i) and the final cipher-text C.
          Intermediate values b(1), b(2)...c(i) are required.
          Encryption is performed in the following manner ('+'
          indicates concatenation):
    
      b(1) = MD5(S + R + A)   c(1) = p(1) xor b(1)   C = c(1)
      b(2) = MD5(S + c(1))    c(2) = p(2) xor b(2)   C = C + c(2)
                   .                       .
                   .                       .
                   .                       .
      b(i) = MD5(S + c(i-1))  c(i) = p(i) xor b(i)   C = C + c(i)
    
          The resulting encrypted String field will contain
          c(1)+c(2)+...+c(i).

          On receipt, the process is reversed to yield the
          plain-text String.