Cryptography – Key management – Key distribution
Reexamination Certificate
2002-07-03
2004-12-14
Vu, Kim (Department: 2135)
Cryptography
Key management
Key distribution
C713S152000, C370S465000
Reexamination Certificate
active
06831981
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an information transceiver system, and in particular to an information transmission device or an information reception device in an information transceiver system for transmitting/receiving specific information.
Recently, owing to developments of communication technologies, various forms by which the information transceiver system transmits/receives information such as cells, packets and frames have been reduced to practice.
In such an information transceiver system, it is important to limit information to be transmitted/received within a specific group or to prevent the information from being recognized by others depending on an importance of the information.
2. Description of the Related Art
FIG. 16
shows an ATM-PON (Asynchronous Transfer Mode Passive Optical Networks) system that is one arrangement of an information transceiver system. This network system is composed of an Optical Line Terminator (hereinafter, abbreviated as OLT)
10
, an optical coupler
30
connected to the OLT
10
, and Optical Network Units (hereinafter, abbreviated as ONU's)
20
_
1
-
20
_n (hereinafter, occasionally represented by a reference numeral
20
; n=64 at the maximum) connected to the optical coupler
30
.
In the ATM-PON system, a transmission of information is performed by cells. The OLT
10
transmits a down cell
41
to the ONU's
20
which respectively receive the same down cell
41
through the optical coupler
30
. The ONU's
20
respectively transmit up cells
42
_
1
-
42
_n to the OLT
10
through the optical coupler
30
. After going through the optical coupler
30
, the up cells
42
_
1
-
42
_n are transmitted to the OLT
10
in time sequence.
G.983 that is ITU-T recommendation is set up in the ATM-PON system. The down cell
41
and the up cell
42
respectively have two types of cells, a user cell and a Physical Layer Operation And Maintenance Cell (hereinafter, abbreviated as PLOAM cell) for management.
The PLOAM cell is periodically multiplexed into a user cell to be transmitted, so that manager information is exchanged between the OLT
10
and the ONU's
20
by using a message field of the PLOAM cell.
The G.983 prescribes the usage of the message field, that is a message called a vendor specific message. A detailed usage of the vendor specific message is not prescribed in the G.983, so that the vendor specific message is permitted to be freely used per vendor.
FIG. 17
shows a format of a down PLOAM cell. This cell is composed of 53 octets, i.e. 5 octets of octet Nos. “1”-“5” for a header field
45
and
48
octets of octet Nos. “6”-“53” for a payload field
46
. The header field
45
includes a 12-bit Virtual Path Identifier (hereinafter, abbreviated as VPI) field, a 16-bit Virtual Channel Identifier (hereinafter, abbreviated as VCI) field, and a 3-bit Payload Type (hereinafter, abbreviated as PT) field.
Destination addresses of cells are indicated in the VPI and VCI fields, and the type of cells such as a user cell or an OAM cell is indicated in the PT field. When the highest bit is “1” in the PT field, it is indicated that the cell is the PLOAM cell. When the highest bit is “0”, it is indicated that the cell is the user cell. It is to be noted that a user network interface has the VPI field only for the lower 8 bits, and a GFC field for the higher 4 bits.
A vendor specific message field
50
is composed of 13 octets of octet Nos. “40”-“52” in the payload field
46
. The Nos. “40” and “41” are respectively a PON-ID (Passive Optical Network Identifier) field
51
and a message ID field
52
. The octet Nos. “42”-“51” and “52” are respectively a message field
53
and a CRC calculation result field
54
.
The PON-ID field
51
is a field for designating an ONU which receives a message. When all of the ONU's are designated, “01000000” is set. When the ONU's are individually designated, a designating PON-ID is set.
The message ID field
52
is a field for indicating a type of a message. When the value thereof is “01111XXX”, it indicates a vendor specific message.
The vendor specific message may be used for so-called SWDL (SoftWare DownLoad) or the like where the OLT
10
supplies a necessary software to the ONU's
20
. However, when the message field in plain text, not ciphered is transmitted as it is, there is a possibility that the contents of the message is disclosed to the ONU's
20
other than the destination ONU.
However, in the G.983, the method of ciphering the message field of the vendor specific message has not been prescribed.
Also, in the G.983, broadcasting of a vendor specific message in which specific ONU's
20
are regarded as forming a single group has not been prescribed. Namely, it has been impossible to perform the ciphering and the broadcasting of the message field.
On the other hand, broadcasting the user cell can be applied to all ONU's
20
such as a cable TV. However, there is a possibility that the user cell in plain text is received by the ONU's
20
other than the destination ONU.
However, in the G.983, while the ciphering method of the user cell is prescribed by churning/dechurning as a usual key for the case the OLT
10
and the ONU
20
are in a one-to-one relationship, the method is not prescribed for the case the OLT and the ONU are in a one-to-many relationship. Namely, it has been impossible to perform a broadcast ciphering of the user cell.
This will be specifically described referring to
FIGS. 18A-18E
.
FIGS. 18A-18E
show an operation example of the ATM-PON system shown in FIG.
16
. This example especially shows a case where a PLOAM cell
44
in the down cell
41
is transmitted from the OLT
10
to the ONU's
20
_
1
-
20
_
4
. Each ONU
20
has its own identifier, the PON-ID.
FIG. 18A
shows PLOAM cells
44
_
1
-
44
_
4
(hereinafter, represented by a reference numeral
44
) transmitted by the OLT
10
.
FIGS. 18B-18E
show the PLOAM cells
44
_
1
-
44
_
4
respectively received by the ONU's
20
_
1
-
20
_
4
.
Both of the ONU's
20
_
1
and
20
_
2
are devices made by a vendor company A, and their vendor ID is “A”. The ONU's
20
_
3
and
20
_
4
are devices respectively made by a vendor company B and a vendor company C, and their vendor ID's are “B” and “C”.
When transmitting a vendor specific message to the ONU
20
_
1
in
FIG. 18A
, the OLT
10
sets the PON-ID of the ONU
20
_
1
in the PON-ID field
51
(see FIG.
17
), and transmits the PLOAM cell
44
_
1
in which a predetermined message is inserted into the message field
53
.
In
FIG. 18B
, the ONU
20
_
1
receives the PLOAM cell
44
_
1
, and receives the message since the PON-ID of the PON-ID field
51
in the PLOAM cell matches its own PON-ID.
In
FIGS. 18C-18E
, each of the ONU's
20
_
2
-
20
_
4
respectively receives the PLOAM cell
44
_
1
, but does not receive the message since the PON-ID set in the PON-ID field
51
does not match its own PON-ID.
When transmitting the vendor specific message to the ONU's
20
_
1
and
20
_
2
that are the devices made by the same vendor company A, the OLT
10
firstly transmits the PLOAM cell
44
_
1
in which the PON-ID of the ONU
20
_
1
is set in the PON-ID field
51
. The ONU
20
_
1
receives the message.
Furthermore, the OLT
10
transmits the PLOAM cell
44
_
2
in which the PON-ID of the ONU
20
_
2
is set in the PON-ID field
51
. The ONU
20
_
2
receives the message.
Also, when the ONU's
20
_
1
-
20
_
3
are made to form a single group and the same message is transmitted to this group, the OLT
10
sets the PON-ID's of the respective ONU's
20
_
1
-
20
_
3
in the PON-ID fields
51
, and sequentially transmits the PLOAM cells
44
_
1
-
44
_
3
in which the same message is inserted into the message field
53
. The ONU's
20
_
1
-
20
_
3
respectively receive the messages from the PLOAM cells
44
in which their own PON-ID's are set.
In
FIG. 18A
, when transmitting the same message to all of the ONU's
20
, the OLT
Edasawa Masanobu
Kuraya Hisayoshi
Fujitsu Limited
Katten Muchin Zavis & Rosenman
Truong Thanhnga
Vu Kim
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