US007188180B2
`
`(12) United States Patent
`Larson et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,188,180 B2
`Mar. 6, 2007
`
`(54) METHOD FOR ESTABLISHING SECURE
`COMMUNICATION LINK BETWEEN
`COMPUTERS OF VIRTUAL PRIVATE
`NETWORK
`
`(75)
`
`Inventors: Victor Larson, Fairfax, VA (US);
`Robert Durham Short, III, Ieesburg,
`VA (US); Edmund Colby Munger.
`Crownsville, MD (US); Michael
`Williamson, South Riding, VA (US)
`
`(56)
`
`References Cited
`
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`Subject to any disclaimer, the term of this
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`
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`
`(Continued)
`Primary Examiner—Krisna Lim
`(74) Attorney, Agent, or Firm—Banner & Witcoff. Ltd.
`
`Related U.S. Application Data
`
`(57)
`
`ABSTRACT
`
`(60) Division of appiicaiioii N0’ 09/558’209’ flied on Apr’
`26’ 2000’ now abandoned’ which is a C°iiiiiiiiaii0ii'
`impan of application NO‘ 09‘/504=783= filed on Feb‘
`15«~ 20005 “OW Pat N” 655025135 which is 3‘ C011‘
`Iinuati°n‘in‘P3-H of application No- 09/429543» filed
`on Oct’ 29> 1999: “OW Pat N°~ 7>O10:604~
`provisional application No. 60/375704’ filed on Jun.
`7, l999: provisional appllcatlop N0. 60/l06:26l, filed
`on ()Ct_ 30 l9r)g_
`i
`
`(60)
`
`(51)
`
`Im;_ C|_
`(2005_() 1)
`G061? 15/173
`(52) U.S. Cl.
`..................................... .. 709/227; 709/228
`(58) Field of Classification Search ...... .. 709/225—229,
`709/245
`Scc application filc for complete Search history.
`
`A technique is disclosed for establishing a secure commu-
`nication link between a first computer and a second com-
`puter over a computer network. Initially, a secure commu-
`nication mode of communication is enabled at a first
`computer without a user cntcring any cryptographic infor-
`mation for establishing the secure communication mode of
`corInI1L1r1icatior1. Then, a secure communication link is estab-
`lished between the first computer and a second computer
`over a computer network based on the enabled secure
`communication mode of communication. The secure com-
`munication link is a Virtual private network communication
`link over the computer. network in which one or more data
`Ya1ueSthf1TV'ar&' according I0 a PSeud0-random Sequence are
`msefied “H0 each dam Packet
`
`41 Claims, 40 Drawing Sheets
`
`REWIVE
`DMS RE UEST
`FORTARG
`SF|'E
`
`\
`PASSTNRU
`REUUESTTO
`OHS SERVER
`
`2705
`\
`RETURN
`'HOS'1éUN
`C/I/N‘
`
`
`ACCESTD
`SECURE SITE
`REQUESTED?
`
`TARGETSITE
`
`1
`
`MICROSOFT 1025
`
`1
`
`MICROSOFT 1025
`
`

`
`US 7,188,180 B2
`Page 2
`
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`
`EP
`EP
`EP
`EP
`EP
`GB
`GB
`GB
`WO
`WO
`W0
`WO
`W0
`W0
`WO
`
`0 814 589
`0 814 589 A
`0 838 930
`0 838 930 A
`0 858 189
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`2 317 792 A
`2 334 181 A
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`Internet: URL:
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`springerlink.com/contenD’4uacOtbOhecoma89/fulltext .pdf>
`(Abstract).
`
`* cited by examiner
`
`2
`
`

`
`U.S. Patent
`
`Mar. 6,2007
`
`Sheet 1 of 40
`
`US 7,188,180 B2
`
`ORIGINATING
`TERMINAL
`
`
`
`JE
`
`
`
`IF PACKET
`
`
`
`
`
`IP ROUTER
`2_2
`
`IP ROUTER
`31
`- _
`
`
`
`
`
`
`
`
`IP ROUTER
`E
`
`
`
`up ROUTER
`
`23.
`
`
`
`INTERNET
`m
`
`IP ROUTER
`fl
`
`up ROUTER
`A
`
`“OUTER
`A
`
`:9 ROUTER
`A
`
`IP ROUTER
`2
`
`
`
`IP ROUTER
`
`E
`
`up ROUTER
`
`_2g _
`
`
`
`
`
`M
`
`
`
`48 ENCRYPTION KEY
`
`DESTINATION
`TERMINAL
`
`FIG. 1
`
`3
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 2 of 40
`
`US 7,188,180 B2
`
` TARP
`TERMINAL
`
`“L0
`
`
`
`TARP PACKET
`
`
`
` IP ROUTER
`:——
`
`
`
`
`
`ROUTER
`
`
`
`FIG. 2
`
` TARP
`TERMINAL
`
`
`M
`
`IP ROUTER
`
`TARP
`
`
`
`RAQFAER
`124
`
`M
`
`IP ROUTER
`M
`
`
`
`4
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 3 of 40
`
`US 7,188,180 B2
`
`2°75‘
`
`207b
`
`207C
`
`207d
`
`° ' '
`
` ‘\330 SESSION-KEY-ENCRYPTED
`
`PAYLOAD DATA
`
`‘\34o TARP PACKET WITH
`ENCRYPTED PAYLOADS
`
`
`
`TARP
`DESTINATION
`
`
`
`‘\ 350 LINK-KEY-ENCRYPTED
`TARP PACKETS
`
`""'"7"~"5"": “\ 360 IP PACKETS w/
`ENCRYPTED TARP
`PACKETS AS PAYLOAD
`
`5
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 4 of 40
`
`US 7,188,180 B2
`
` goyb
`
`207(;
`
`gm . . .
`
`/300 DATASTREAM
`
`
`
`48
`Ifljlliljllijjjj
`
`
`‘\52o BLOCK-ENCRYPTED
`(SESSION-KEY) PAYLOAD
`
`SEQUENCE
`- -"‘-"5-59 :3: ‘\522 ENCRYPTED BLOCK
`
`DIVIDED INTO PAYLOADS
`
`
`
`DIVIDED INTO PAYLOADS
`INTERLEAVED
`
`5‘ ‘\523 ENCRYPTED BLOCK
`DNIDED INTO PAYLOADS
`INTERLEAVED
`
`‘\34o TARP PACKETS WITH
`ENCRYPTED PAYLOADS
`
`6
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 5 of 40
`
`US 7,188,180 B2
`
`TARP TRANSCEIVER
`E
`
`NETWORK (|P) LAYER
`M
`
`
`
`ONE ALTERNATIVE TO
`COMBINE
`TARP PROCESSING
`WITH OIS IP
`PROCESSOR
`
`TARP LAYER
`M
`
`OTHERALTERNATIVE
`T0 COMBINE
`TARP PROCESSING
`WITH D.L. PROCESSOR
`(e.g., BURN INTO BOARD
`
`PROM) PROTOCOL WRAPPER
`
`DATA LINK LAYER
`fl
`
`FIG. 4
`
`7
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 6 of 40
`
`US 7,188,180 B2
`
`
`
`BACKGROUND LOOP - DECOY
`GENERATION
`
`AUTHENTICATE TARP
`PACKET
`
`OUTER LAYER DECRYPTION
`OF TARP PACKET USING
`LINK KEY
`
`
`CHECK FOR DECOY AND
`INCREMENT PERISHABLE
`
`DECOY COUNTER AS-
`
`APPROPRIATE
`
`TRANSMIT DECOY?
`
`YES
`
`DECREMENT
`TTL TTL > 0?
`
`S5
`
`S7
`
`
`
`
`
`
`
`
`
`DUMP DECOY
`
`
`
`
`GENERATE NEXT-HOP TARP
`ADDRESS AND STORE LINK
`KEY AND IPADDRESS
`
`
`
`DETERMINE DESTINATION
`TARP ADDRESS AND STORE
`LINK KEY AND IP ADDRESS
`
`
`
`
`
`
`GENERATE NEXT-HOP TARP
`ADDRESS AND STORE LINK
`KEYAND IP ADDRESS
`
`
`
`
`
`GENERATE IP HEADER
`AND TRANSMIT
`
`
`310
`
`S11
`
`FIG. 5
`
`8
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 7 of 40
`
`US 7,188,180 B2
`
`BACKGROUND LOOP - DECOY
`GENERATION
`
`GROUP RECEIVED IP PACKETS
`INTO INTE RLEAVE WINDOW
`
`DETERMINE DESTINATION TARP
`
`ADDRESS, INITIALIZE TTL, STORE
`IN TARP HEADER
`
`RECORD WINDOW SEQ. NOS. AND
`INTERLEAVE SEQ. NOS. IN TARP
`HEADERS
`
`CHOOSE FIRST HOP TARP
`ROUTER, LOOK UP IP ADDRESS
`AND STORE IN CLEAR IP HEADER,
`OUTER LAYER ENCRYPT
`
`INSTALL CLEAR IP HEADER AND
`TRANSMIT
`
`FIG. 6
`
`9
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 8 of 40
`
`US 7,188,180 B2
`
`S49
`
`
`
`DIVIDE BLOCK INTO PACKETS
`USING WINDOW SEQUENCE
`DATA, ADD CLEAR IP HEADERS
`GENERATED FROM TARP
`HEADERS
`
`HAND COMPLETED IP PACKETS
`TO IP LAYER PROCESS
`
`
`
`$50
`
`BACKGROUND LOOP - DECOY
`GENERATION
`
`S40
`
`AUTHENTICATE TARP PACKET
`RECEIVED
`
`S42
`
`DECRYPT OUTER LAYER
`ENCRYPTION WITH LINK KEY
`
`S43
`
`INCREMENT PERISHABLE
`COUNTER IF DECOY
`
`S44
`
`THROW AWAY DECOY OR KEEP
`IN RESPONSE TO ALGORITHM
`
`S45
`
`S47
`
`CACHE TARP PACKETS UNTIL
`WINDOW IS ASSEMBLED
`
`S46
`
`DEINTERLEAVE PACKETS
`FORMING WINDOW
`
`DECRYPT BLOCK
`
`348
`
`FIG. 7
`
`10
`
`10
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 9 of 40
`
`US 7,188,180 B2
`
`T{(:'H/§|r‘|£;1,;,|_
`301
`
`SSYN
`PAg2K|ET
`
`SSYN ACK
`PACKET
`822
`
`SSYN ACK
`ACK PACKET
`823
`
`
`
`825
`SECURE SESSION
`|N|T|AT|0N ACK
`
`824
`SECURE SESS|ON
`INITIATION
`
`FIG. 8
`
`11
`
`11
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 10 of 40
`
`US 7,188,180 B2
`
` ROUTER
`
`TRANSMIT TABLE
`RECEIVE TABLE
`921
`924
`TAT L.
`131.218.204.98
`-
`131.218.204.65
`131.218.204.98
`-
`131.218.204.65
`131.218.204.221
`-
`131.218.204.97
`131.218.204.221
`-
`131.218.204.97
`131.218.204.139
`.
`131.218.204.186
`131.218.204.139
`-
`131.218.204.188
`131.218.204.12
`-
`131.218.204.55
`131.218.204.12
`.
`131.218.204.55
`
`TRANSMIT TABLE
`RECEIVE TABLE
`923
`922
`233 2:52
`131.218.204.151
`-
`131.218.204.89
`131.218.204.161
`-
`131.218.204.89
`131.218.204.66
`-
`131.218.204.212
`131.218.204.66
`-
`131.218.204.212
`131.218.204.201
`.
`131.218.204.127
`131.218.204.201
`-
`131.218.204.127
`131.218.204.119
`-
`131.218.204.49
`131.218.204.119
`-
`131.218.204.49
`
`.
`
`12
`
`12
`
`

`
`U.S. Patent
`
`Mar. 6,2007
`
`Sheet 11 of 40
`
`US 7,188,180 B2
`
`FIG. 10
`
`13
`
`13
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 12 of 40
`
`US 7,188,180 B2
`
`8:
`
`8:
`
`
`
`$3:m_>_<Emzfifi
`
`
`
`
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`
`14
`
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`
`
`
`
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 13 of 40
`
`US 7,188,180 B2
`
`o3:01;:
`
`EgEEQm
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`$3
`
`zo_E_§<
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`
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`
`15
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`
`15
`
`
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 14 of 40
`
`US 7,188,180 B2
`
`
`
`
`
`MODE
`OR
`
`
`
`
`1.PROM|SCUOUS
`
`HARDWARE
`
`IP ADDRESSES
`
`DlSCR|MINATOR FIELD
`
`SAME FOR ALL NODES
`
`OR %9\ArGE%Eh}ELY
`
`°A'Y,§§Q’,fi‘§'E“
`
`CA“"$‘§,‘,’,§§'ED
`
`2. PROMISCUOUS
`PER VPN
`
`
`
`FIXED FOR EACH VPN
`
`
`
`CAN BE VARIED
`lN SYNC
`
`
`
`
`CAN BE VARIED
`WSYNC
`
`3. HARDWARE
`HOPPING
`
`CAN BE VARIED
`IN SYNC
`
`CAN BE VARIED
`IN SYNC
`
`CAN BE VARIED
`IN SYNC
`
`
`
`
`
`FIG. 12B
`
`16
`
`16
`
`

`
`S.U
`
`4|.nmM
`
`wM
`
`.mHm7M2/09
`
`US 7,188,180 B2
`
`mE8
`
`.32
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`82
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`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 16 of 40
`
`US 7,188,180 B2
`
`CURRENT IP PAIR ‘R---
`
`SENDER'S ISP
`
`CURRENT IP PAIR
`
`ckpt_o
`ckpt_n
`
`TRANSMITTER
`
`REC|P|ENT'S ISP
`
`KEPT IN SYNC FOR SENDER T0 RECIPIENT SYNCHRONIZER 4 --------------------- - - >
`
`KEPTIN SYNC FOR RECIPIENT TO SENDER SYNCHRONIZER
`
`FIG. 14
`
`18
`
`18
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 17 of 40
`
`US 7,188,180 B2
`
`@
`
`SYNC_REQ
`
`@ WHEN SYNCHRONIZATION
`BEGINS TRANSMIT (RETRANSMIT
`PERIODICALLY UNTIL ACKed)
`SYNC_REQ USING NEW
`TRANSMITTER CHECKPOINT IP
`PAIR ckpI_n AND GENERATE
`NEW RECEIVER RESPONSE
`
`CHECKPOINT ckpI_r
`
`# WHEN SYNC_ACK
`ARRIVES WITH INCOMING
`
`HEADER = ckptjz
`GENERATE NEW
`CHECKPOINT IP PAIR
`
`ckpI_n IN TRANSMITTER
`
`II
`
`* WHEN SYNC_REQ ARRIVES
`WITH INCOMING HEADER =
`
`W
`
`RECEIVER'S cI(pt_n:
`-UPDATE WINDOW
`-GENERATE NEW
`CHECKPOINT IP PAIR
`ckpt_n IN RECEIVER
`-GENERATE NEW
`CHECKPOINT IP PAIR
`
`ckpI_r IN TRANSMITTER
`-TRANSM IT SYNC_ACK
`USING NEW CHECKPOINT
`
`IP PAIR ckpI_r
`
`FIG. 15
`
`19
`
`19
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 18 of 40
`
`US 7,188,180 B2
`
`20
`
`20
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 19 of 40
`
`US 7,188,180 B2
`
`000 —
`
`
`
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`
`C
`
`W'””°W'S'ZE Vllllllllll
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`
`VIIIIIIIIIIIA
`
`WIIIIIIIIIII.
`WIIIIIIIIIIA
`
`‘ VIIIIIIIIIIJ
`
`21
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 20 of 40
`
`US 7,188,180 B2
`
`
`
`VIIIIIIIIIIA
`
`O O
`
`VIIIIIIIIIIIA
`WIIIIIIIIIIA
`WIIIIIIIIIIA
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`%555%555i
`
`000
`
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`
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`
`22
`
`22
`
`

`
`U.S. Patent
`
`Mar. 6,2007
`
`Sheet 21 of 40
`
`US 7,188,180 B2
`
`WIIIIIIIIIII
`
`
`
`
`
`
`
`TIIIIIIIIIIA
`VIIIIIIIIIIA
`VIIIIIIIIIIA
`
`
`
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`I INACTIVE
`Q ACTIVE
`E USED
`
`WIIIIIIIIIJI
`WIIIIIIIIIIJ
`WIIIIIIIIIIA
`WIIIIIIIIIIZ
`WIIIIIIIIIIA
`
`
`
`
`
`000
`
`
`
`711111111114
`
`
`
`FIG. 19
`
`23
`
`
`
`O00
`
`W|NDOW_S|ZE
`
`W|NDOW_SlZE
`
`23
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 22 of 40
`
`US 7,188,180 B2
`
`
` COMPUTER #2
`
`
`
`
` COMPUTER#1
`
`2008
`
`24
`
`24
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 23 of 40
`
`US 7,188,180 B2
`
`ADTABLE
`
`2101
`
`2102
`
`2103
`
`so TABLE
`
`- 2104
`
`BE TABLE
`
`LINKDOWN V 2105
`
`BFTABLE
`
`lIIII|I|lIIIlII|l|IlIII|
`
`2106
`
`2107
`
`2108
`
`CFTABLE
`
`FIG. 21
`
`25
`
`25
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 24 of 40
`
`US 7,188,180 B2
`
`
`
`
`
`
`MORE THAN
`ONE TRANSMITTER
`
`TURNED ON?
`
`MEASURE
`QUALITY OF
`TRANSMISSION
`PATH X
`
`PATH X
`QUALITY < THRESHOLD?
`
`
`PATH X
`WEIGHT LESS THAN
`STEADY STATE
`
`VALUE?
`
`DECREASE WEIGHT
`FOR PATH X
`
`2208
`
`
`
`
`INCREASE
`WEIGHT FOR PATH X
`TOWARD STEADY
`STATE VALUE
`
`2206
`
`ADJUST WEIGHTS
`FOR REMAINING
`PATHS SO THAT
`WEIGHTS EQUAL ONE
`
`
`
`
`
`FIG. 22A
`
`26
`
`26
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 25 of 40
`
`US 7,188,180 B2
`
`(EVENT) TRANSMITTER
`FOR PATH X
`TURNS OFF
`
`
`
`
`2210
`
`AT LEAST
`ONE TRANSMITTER
`TURNED ON?
`
`
`DROP ALL PACKETS
`UNTILATRANSMITTER
`
`TURNS 0N
`
`SET WEIGHT
`
`TO ZERO
`
`ADJUST WEIGHTS
`
`
`
`
`
`
`FOR REMAINING PATHS
`
`
`SO THAT WEIGHTS
`
`EQUAL ONE
`
`
`
`FIG. 22B
`
`27
`
`27
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 26 of 40
`
`US 7,188,180 B2
`
`PATH X1
`
`
`
`
`
`2308
`\
`
`TRANSMIT TABLE
`
`2302
`
`PACKET
`TRANSMITTER
`
`PATH X2
`
` w (X1) = 0.2
`w (X2) = 0.1
`
`w (X3) = 0.6
`
`w (X4) = 0.1
`
`2301
`
`
`
`
`
`
`
`LINK QUALITY
`MEASUREMENT
`FUNCTION
`
`FIG. 23
`
`28
`
`28
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 27 of 40
`
`US 7,188,180 B2
`
`
`
`
`COMPUTER
`
`2403
`
`2404
`
`
`9 100Mb/s MESST= 32 9
`
`
`
`COMPUTER
`
`9 25Mb/s MESST=8
`
`FIG. 24
`
`29
`
`29
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 28 of 40
`
`US 7,188,180 B2
`
`2501
`
`2504
`
`WEB
`BROWSER
`
`
`
`2502
`
`
`
`PAGE RESP
`
`FIG. 25
`(PRIOR ART)
`
`30
`
`30
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 29 of 40
`
`US 7,188,180 B2
`
`2602
`
`VVEB
`
`BROWSER
`
`
`
`
`GAIEKEEPER 2603
`
`IP
`HOPHNG
`
`UNSECURE
`TARGET
`$TE
`
`
`
`FIG. 26
`
`2611
`
`31
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 30 of 40
`
`US 7,188,180 B2
`
`
`
` RECEIVE
`DNS REQUEST
`FOR TARGET SITE
`
`
`
`USER
`AUTHORIZED TO
`CONNECT?
`
`
`
`
`RETURN
`"HOST UNKNOWN"
`ERROR
`
`FIG. 27
`
`32
`
`2701
`
`2706
`
`32
`
`

`
`U.S. Patent
`
`Mar. 6,2007
`
`Sheet 31 of 40
`
`US 7,188,180 B2
`
`2803
`
`HOST
`
`EDGE
`ROUTER
`
` 2801
`COMPUTER#1
`
`2804
`
`HOST
`COMPUTER#2
`
`
`
`FIG. 28
`
`33
`
`33
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 32 of 40
`
`US 7,188,180 B2
`
`2901
`
` HOSTCOMPUTER#1
`
`EDGE
`ROUTER
`
`HOSTCOMPUTER#2
`
`
`
`
`2902
`
`
`TX
`
`2903
`
`RX
`
`FIG. 29
`
`34
`
`34
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 33 of 40
`
`US 7,188,180 B2
`
`gzoawm
`Ema3
`
`
`
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`
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`
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`
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`
`35
`
`35
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 34 of 40
`
`US 7,188,180 B2
`
`3103
`
`CLlENT#2
`
`
`
`
`3105
`
`HACKER
`
`FIG. 31
`
`36
`
`36
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 35 of 40
`
`US 7,188,180 B2
`
`CLIENT
`
`SERVER
`
`PASS DATA UP STACK
`
`ckpI_o=ckpt_n
`GENERATE NEW ckpI_n
`GENERATE NEW ckpt_r FOR
`TRANSMITTER SIDE
`
`TRANSMIT SYNC_ACK
`CONTAINING ckpI_o
`
`ckpt_o=ckpI_n
`GENERATE NEW ckpt_n
`GENERATE NEW ckpt_r FOR
`TRANSMITTER SIDE
`
`TRANSMIT SYNC_ACK
`CONTAINING ckpt_o
`
`SEND DATA PACKET
`
`USING ckpI_n
`CKPT_D=ckpI_n
`GENERATE NEW ckpI_n
`START TIMER, SHUT TRANSMITTER
`OFF
`
`IF CKPT_O IN SYNC_ACK
`MATCHES TRANSMITTER'S
`
`ckpt_o
`UPDATE RECEIVER'S
`
`ckpt_r
`KILL TIMER, TURN
`TRANSMITTER ON
`
`SEND DATA PACKET
`
`USING ckpI_n
`ckpt_o=ckpI_n
`GENERATE NEW ckpI_n
`START TIMER, SHUT TRANSMITTER
`OFF
`
`WHEN TIMER EXPIRES
`TRANSMITSYNC_REQ
`USINGTRANSMITTERS
`
`ckpI_o,STARTTIMER
`
`IF ckpI_o IN SYNC_ACK
`MATCHES TRANSMITTER'S
`
`ckpt_o
`UPDATE RECEIVER'S
`
`ckpt_r
`KILL TIMER, TURN
`TRANSMITTER ON
`
`SYNC-REQ
`
`FIG. 32
`
`37
`
`37
`
`

`
`U.S. Patent
`
`3
`
`4
`
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`
`2
`
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`
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`
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`38
`
`38
`
`
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 37 of 40
`
`US 7,188,180 B2
`
`3400
`
`3401
`
`
`
`DISPLAY WEB PAGE
`CONTAINING GO
`SECURE HYPERLINK
`
` E
`
`
`
`LAUNCH LINK TO
`.COM SITE
`
`DOWNLOAD AND
`INSTALL PLUG-IN
`
`CLOSE CONNECTION
`
`3404
`
`3405
`
`3406
`
`AUTOMATIC REPLACEMENT OF TOP—LEVEL
`DOMAIN NAME WITH SECURE TOP-LEVEL
`DOMAIN NAME
`
`3407
`
`3412
`
`DISPLAY "SECURE" ICON
`
`ACCESS SECURE PORTAL AND
`SECURE NETWORK AND SECURE DNS
`
`OBTAIN SECURE COMPUTER NETWORK
`ADDRESS FOR SECURE WEBSITE
`
`ACCESS GATE KEEPER AND RECEIVE
`PARAMETERS FOR ESTABLISHING VPN
`WITH SECURE WEBSITE
`
`3408
`
`3409
`
`3410
`
`3413
`
`
` TERMINATE
`
`
`SECURE
`CONNECTION
`
`YES
`REPLACESECUREWLEVEL
`DOMAIN NAME WITH NON-SECURE
`TOP-LEVEL DOMAIN NAME
`
`3414
`
`3415
`
`DISPLAY "GO SECURE" HYPERLINK
`
`CONNECT TO SECURE WEBSITE
`USING VPN BASED ON PARAMETERS
`ESTABLISHED BY GATE KEEPER
`
`I
`
`3411
`
`FIG. 34
`
`39
`
`39
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 38 of 40
`
`US 7,188,180 B2
`
`3501
`
`
`
`
`AND LOGS mm SECURE
`DOMAIN NAME REGISTRY SERVICE
`
`REQUESTORACCESSES WEBSITE
`
`3500
`
`\
`
`REQUESTER COMPLETES ONLINE
`REGISTRATION FORM
`
`
`
`QUERY STANDARD DOMAIN NAME
`SERVICE REGARDING OWNERSHIP
`OF EQUIVALENT NON-SECURE
`DOMAIN NAME
`
`DOMAIN NAME REGISTRY
`
`RECEIVE REPLY FROM STANDARD
`
`
`
`INFORM REQUESTOR
`OF CONFLICT
`
`3506
`
`3505
`
`NO
`
`VERIFY INFORMATION AND
`ENTER PAYMENT INFORMATION
`
`3507
`
`
`
`REGISTER SECURE DOMAIN NAME
`
`
`
`3508
`
`FIG. 35
`
`40
`
`40
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 39 of 40
`
`US 7,188,180 B2
`
`3611
`
`3610
`
`
`
`WEB SERVER
`
`SERVER PROXY
`
`VPN GUARD
`
`
`
`COMPUTER NETWORK
`
`3602
`
`
`
`FIREWALL
`
`
`
`CLIENT COMPUTER
`
`3607
`
`3604
`
`FIG. 36
`
`41
`
`

`
`U.S. Patent
`
`Mar. 6, 2007
`
`Sheet 40 of 40
`
`US 7,188,180 B2
`
`to~.n :3O
`
`/
`
`GENERATE MESSAGE PACKETS
`
`3701
`
`MODIFY MESSAGE PACKETS WITH PRIVATE
`CONNECTION DATA AT AN APPLICATION LAYER
`
`3702
`
`SEND TO HOST COMPUTER
`THROUGH FIREWALL
`
`RECEIVE PACKETS AND AUTHENTICATE
`AT KERNEL LAYER OF HOST COMPUTER
`
`RESPOND TO RECEIVED MESSAGE
`PACKETS AND GENERATE REPLY
`MESSAGE PACKETS
`
`MODIFY REPLY MESSAGE PACKETS WITH
`PRIVATE CONNECTION DATA AT A
`KERNEL LAYER
`
`SEND PACKETS TO CLIENT COMPUTER
`THROUGH FIREWIRE
`
`RECEIVE PACKETS AT CLIENT
`COMPUTER AND AUTHENTICATE AT
`APPLICATION LAYER
`
`FIG. 37
`
`3703
`
`3704
`
`3705
`
`3705
`
`3707
`
`3703
`
`42
`
`

`
`US 7,188,180 B2
`
`1
`METIIOD FOR ESTABLISIIIIVG SECURE
`COMMUNICATION LINK BETWEEN
`COMPUTERS OF VIRTUAL PRIVATE
`NETVVORK
`
`CROSS-RF,FF,RFNCF, TO RFI .ATF,T)
`APPLICATIONS
`
`This application claims priority from and is a divisional
`patent application ofU.S. application Ser. No. 09/558,209,
`filed Apr. 26, 2000, now abandoned which is a continuation-
`in-part patent application of previously-filed U.S. applica-
`tion Ser. No. 09/504,783, filed or1 Feb. 15, 2000, now U.S.
`Pat. No. 6,502,135,
`issued Dec. 31, 2002, which claims
`priority from and is a continuation-in-part patent application
`of previously—filed U.S. application Ser. No. 09/429,643,
`filed on Oct. 29, 1999. now U.S. Pat. No. 7,010,604, issued
`Mar. 7, 2006, The subject matter ofU.S. application Ser. No.
`09/429,643, which is bodily incorporated herein, derives
`from provisional U.S. application Nos. 60/106,261 (filed
`Oct. 30, 1998) and 60/137,704 (filed Jun. 7, 1999). The
`present application is also related to U.S. application Ser.
`No. 09/558,210, filed Apr. 26, 2000, and which is incorpo-
`rated by reference herein.
`BACKGROUNT) OF THF, INVFNTION
`
`A tremendous variety of met iods have been proposed and
`implemented to provide security and anonymity for com-
`munications over the Internet. The variety stems, in part,
`from the dilferent needs of di “erent Internet users. A basic
`heuristic framework to aid in discussing these di erent
`security techniques is illustrated ir1 FIG. 1. Two terminals, an
`originating terminal 100 and a destination terminal 110 are
`in communication over the Internet. It is desired for the
`communications to be secure, that is, innnune to eavesdrop-
`ping. For example, terminal 100 may transmit secret infor-
`mation to terminal 110 over the Internet 107. Also, it may be
`desired to prevent an eavesdropper from discovering that
`terminal 100 is in communication with terminal 110. For
`example, if terminal 100 is a user and terminal 110 hosts a
`web site, terminal 100’s user may not want anyone in the
`intervening networks to know what web sites he is "visit-
`ing.” Anonymity would thus be an issue, for example, for
`companies that want to keep their market research interests
`private and thus would prefer to prevent outsiders from
`knowing which web-sites or other Internet resources they
`are “visiting.” These two security issues may be called data
`security and anonymity, respectively.
`Data security is usually tackled using some form of data
`encryption. An encryption key 48 is known at both the
`originating and terminating terminals 100 and 110. The keys
`may be private and public at the originating and destination
`terminals 100 and 110, respectively or they may be sym-
`metrical keys (the same key is used by both parties to
`encrypt and decrypt). Many encryption methods are known
`and usable in this context.
`To hide traffic from a local administrator or ISP, a user can
`employ a local proxy server in communicating over an
`encrypted channel with an outside proxy such that the local
`administrator or ISP only sees the encrypted traflic. Proxy
`servers prevent destination servers from determining the
`identities of the originating clients. This system employs an
`intermediate server interposed between client and destina-
`tion server. The destination server sees only the Internet
`Protocol
`address of the proxy server and not
`the
`originating client. The target server only sees the address of
`
`2
`the outside proxy. This scheme relies on a trusted outside
`proxy server. Also, proxy schemes are vulnerable to traffic
`analysis methods of determining identities of transmitters
`and receivers. Another important limitation of proxy servers
`is that the server knows the identities of both calling and
`called parties. In many instances, an originating terminal,
`such as tenninal A, would prefer to keep its identity con-
`cealed from the proxy, for example, if the proxy server is
`provided by an Internet service provider (ISP).
`To defeat traffic analysis, a scheme called Chaum’s mixes
`employs a proxy server that transmits and receives fixed
`length messages,
`including dummy messages. Multiple
`originating terminals are cormected through a r11ix (a server)
`to multiple target servers. It is difiicult to tell which of the
`originating terminals are communicating to which of the
`cormected target servers, and the dummy messages confuse
`eavesdroppers’ elforts to detect communicating pairs by
`analyzing traflic. A drawback is that there is a risk that the
`mix server could be compromised. One way to deal with this
`risk is to spread the trust among multiple mixes. If one mix
`is compromised, the identities of the originating and target
`terminals may remain concealed. This strategy requires a
`number of alternative mixes so that the intermediate servers
`interposed between the originating and target terminals are
`not determinable except by compromising more than one
`mix. The strategy wraps the mes sage with multiple layers of
`encrypted addres ses. The first mix in a sequence can decrypt
`only the outer layer of the message to reveal
`the next
`destination mix in sequence. The second mix can decrypt the
`message to reveal the next mix and so on. The target server
`receives
`the message
`and,
`optionally,
`a
`rnulti-layer
`encrypted payload containing return information to send
`data back in the same fashion. The only way to defeat such
`a mix scheme is to collude among mixes. If the packets are
`all fixed-length and intermixed with dummy packets, there
`is no way to do any kind of traffic analysis.
`Still another anonymity technique, called ‘crowds,’ pro-
`tects the identity of the originating terminal from the inter-
`mediate proxies by providing that originating terminals
`belong to groups of proxies called crowds. The crowd
`proxies are interposed between originating and target tenni-
`nals. Each proxy through which the message is sent
`is
`randomly chosen by an upstream proxy. Each intermediate
`proxy can send the message either to another randomly
`chosen proxy in the “crowd” or to the destination. Thus,
`even crowd members cannot determine if a preceding proxy
`is the originator of the message or if it was simply passed
`fron1 another proxy.
`7.KS (7ero-Knowledge Systems) Anonymous IP Protocol
`allows users to select up to any of five different pseudonyms,
`while desktop software encrypts outgoing traffic and wraps
`it ir1 User Datagram Protocol (UDP) packets. The first server
`in a 2+-hop system gets the UDP packets, strips olf one layer
`of encryption to add another, then sends the tralfic to the next
`server, which strips olf yet another layer of encryption and
`adds a new one. The user is permitted to control the number
`of hops. At the final server, traflic is decrypted with an
`untraceable IP address. The technique is called onion-rout-
`ing. This method can be defeated using tralfic analysis. For
`a simple example, bursts of packets from a user during
`low-duty periods can reveal the identities of sender and
`receiver.
`Firewalls attempt to protect LANs from unauthorized
`access and hostile exploitation or damage to computers
`cormected to the LAN. Firewalls provide a server through
`which all access to the LAN must pass. Firewalls are
`centralized systems that require administrative overhead to
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`maintain. They can be compromised by virtual-machine
`applications (“applets”). They instill a false sense of security
`that leads to security breaches for example by users sending
`sensitive information to servers outside the firewall or
`encouraging use of modems to sidestep the firewall security.
`Firewalls are not useful for distributed systems such as
`business travelers, extranets, small teams, etc.
`
`SUMMARY OF Tl TE TNVENTTON
`
`A secure n1ecl1anisn1 for co1nn1unicati11g over the i11ten1et,
`including a protocol referred to as the Tunneled Agile
`Routing Protocol (TARP), uses a unique two—layer encryp-
`tion format and special TARP routers. TARP routers are
`similar ir1 function to regular lP routers. Each TARP router
`has one or more IP addresses and uses normal IP protocol to
`send lP packet messages (“packets” or “datagrams”). The lP
`packets exchanged between TARP terminals via TARP rout-
`ers are actually encrypted packets whose true destination
`address is concealed except to TARP routers and servers.
`The normal or “clear” or “outside” lP header attached to
`TARP IP packets contains only the address of a next hop
`router or destination server. That is, instead of indicating a
`final destination in the destination field of the IP header, the
`TARP packet’s lP header always points to a next-hop in a
`scrics of TARP routcr hops, or to thc final dcstination. This
`means there is no overt indication from an intercepted TARP
`packet of the true destination of the TARP packet since the
`destination could always be next-hop TARP router as well as
`thc final dcstination.
`
`Each TARP packet’s true destination is concealed behind
`a layer of encryption generated using a li11k key. The li11k key
`is the encryption key used for encrypted communication
`between the hops intervening between an originating TARP
`terminal and a destination TARP terminal. Each "ARP
`router can remove tl1e outer layer of encryption to reveal tl1e
`destination router for each TARP packet. To identify the link
`key needed to decrypt the outer layer of encryption of a
`TARP packet, a receiving TARP or routing terminal may
`identify tl1e transmitting terminal by tl1e sender/receiver IP
`numbers in the cleartext lP header.
`
`Once the outer layer of encryption is removed, the TARP
`router determines the final destination. Each TARP packet
`140 undergoes a 111inin1un1 ntunber of hops to help foil traflic
`analysis. The hops may be chosen at random or by a fixed
`Value. As a result, each TARP packet may make random trips
`among a number of geographically disparate routers aefore
`reacl1ing its desti11ation. Each trip is highly likely to be
`dififerent
`for each packet composing a given message
`because each trip is independently randomly determined.
`This feature is called agile routing. The fact that di erent
`packets take different routes provides distinct advantages by
`making it diflicult for an interloper to obtain all the packets
`forming an entire multi-packet message. The associated
`advantages have to do with the inner layer of encryption
`discussed below. Agile routing is combined with another
`feature that furthers this purpose; a feature that ensures that
`any message is broken into multiple packets.
`The IP address of a TARP router can be changed, a feature
`called IP agility. Each TARP router, independently or u11der
`direction from another TARP terminal or router, can change
`its IP address. A separate, unchangeable identifier or address
`is also defined. "his address. called the TARP address, is
`known only to TARP routers and terminals and may be
`correlated at any time by a TARP router or a TARP terminal
`using a Lookup Tablc (LUT). Whcn a TARP routcr or
`
`4
`terminal changes its IP address, it updates the other TARP
`routers and temiinals which in turn update their respective
`LUTs.
`The message payload is hidden behind a11 inner layer of
`encryption in the TARP packet that can only be unlocked
`using a session key. The session key is not available to any
`of the intervening TARP routers. The session key is used to
`decrypt the payloads of the TARP packets permitting the
`data stream to be reconstructed.
`Communication may be made private using link and
`session keys, which in turn may be shared and used accord-
`ing to any desired method. For example, public/private keys
`or synunetric keys may be used.
`To transmit a data stream, a TARP originating terminal
`constructs a scrics of TARP packets from a series of IP
`packets generated by a network (IP) la