WO2010149041A1

WO2010149041A1 - Radio frequency system, radio frequency device and security processing method

Info

Publication number: WO2010149041A1
Application number: PCT/CN2010/074304
Authority: WO
Inventors: 南相浩
Original assignee: 北京易恒信认证科技有限公司
Priority date: 2009-06-23
Filing date: 2010-06-23
Publication date: 2010-12-29
Also published as: CN101582123A; CN101582123B

Abstract

A radio frequency system, a radio frequency device t and a security processing method are provided. The system comprises a writer, a card reader and a radio frequency card, three Linear Feedback Shift Registers (LFSR) are set respectively corresponding to the User Identifier(UID) domain, the recharging domain, and the balance domain of the radio frequency card; CPK-keys are also comprised and embedded in the writer and the card reader; three keys are set in the CPK-key and are respectively utilized for encrypting a recharging data, a balance data and a controlling parameter; the feedback and the carry bit of the LFSR are controlled by the controlling parameter, and the difficulty of anatomical analysis is increased; the difficulty of counterfeiting is increased by a digital signature participated by the content of the LFSR; and the difficulty of duplicating is increased by a question and answer mechanism.

Description

Wood field

This and the safety technology field are particularly relevant to systems and systems. Background

adoFeq e cy de ca o R wood and you can, the wood foot can be used to establish or connect with the specific system. R wood

In the field of, transportation cards, and so on.

In recent years, there is a new R card in addition to the general R. A Cad ae card has functions other than storage functions.

The R-foot card of the foot is basically the same as the safety requirement. The foot can only solve the physical characteristics. The ability of the method can only solve the physical method. Therefore, the world's physical and combined approach has a physical indication that the physical devices are not enough to prevent the physical devices from being formed like a card.

R is particularly difficult to maintain in all areas of the card, and the most needed users in the R special card are e de ca o 佰 and more.

First of all, the primary characteristic of R is the only one of the user's only ones. in case

That's more.

If 佰, for example, 英西佰一 50 another 佰 1000 then 1000 elements to 50 cards.

If the rest is left, the rest of the remaining ones will be preserved. Otherwise, the remaining surplus will be refurbished.

As shown in Figure 1, she indicated her W e The mutual security of TAG and Reade.

The characteristics of the card reflect the different understanding of the system.

The TAG and Reade's same card highlight the mutual interaction of the device and the device, and thus have to pick up certain intelligent functions for the devices in the middle and the live device. However, it is impossible for the interaction to be sufficient for active devices such as active devices. So there is an insurmountable fatal hole

1 There is a medium in the wood and a 16-segment reverse shift register ea Feedbac Sh Reg e SR.

So well known, the sequence can be sufficient

There is a cphe foot in the wood in the 48 anti-shift register. The cphe's sum and the external input are connected to the generator and the user, so the early-out reverse shift register 佰 provides the dependency.

3 There is a way to analyze the synchronization of the TAG and the cphe in the wood.

As a result, her unreliable recent card cracking and gho's ability to legally produce a legal card will cause a lot of panic and use inside and outside. Content

The purpose of this and the purpose is to provide a systematic and safe method that can greatly improve the security and greatly reduce the stringent requirements of TAG.

The present invention provides a system including a device and a device, and respectively, 佰, and 、, respectively, a three-dimensional inverse shift register

The system includes CP ey which is embedded in the device And the device has a group break function

CP ey is separate from Yu and Yu and controlled

The anti-shift register is inverted and the control is controlled by the inverse of the contents of the shift register.

This and the purpose of the three-in-one 32-reverse anti-shift register to control the TAG, 佰, 余

The first inverse shift register is controlled by the signature 佰 the second inverse shift register is controlled by the signature of the 佰, and the third inverse register is controlled by the signature of the remainder.

This and the purpose of providing a systematic approach to security, including the following steps

Step A: CP ey uses the group break method to be safe. Step B: Embed CP ey and West to make it a group break function.

The rest of the line is safe for her.

The beneficial effects of this and the meta-system, and the security method are based on the group-based method, especially the CPK grouping method, which is signed and controlled by UD and 佰, and the use of multi-reactor is controlled and controlled. The same FD device does not exist to prevent, prevent, and secure the small amount of money in various payment systems.

1 foot has a wooden element system

2 foot and the RF system

3 foot and the security of the metasystem Hugh way

The purpose of this and the wood plan and the clearer understanding of the following combination and the safety of a system, and a safe method. It is understood that this is the use of her and is not intended to limit this. This and the wood of CP are in W e,

The TAG and Reade are the same as the other ones. The groupings are specially made. The CPs are grouped into a wooden and connected to each other to provide a proxy tool such as signature and reconciliation. Because the power-active smart devices of the sum can be mutually equal, the safety can be greatly improved, and the safety is greatly reduced.

Demanding requirements.

In areas such as transportation and transportation cards, the most feared places are enough, 佰, and Yu. Because the birth defects such as the card in the middle are not changed

The TAG is a good solution.

The binary system shown in Figure 2 includes W e Reade and TAG.

W e Reade and TAG respectively include , 佰 , and

The s, s, and s 3, respectively, the same sex inverse shift register division) respectively SR SR FSR as shown in Table 1.

, 佰 , 余 SR

Signature FSR output

6B 8B 32 32

佰6B 8B 32 32 6B 8B 32 32 This system and system include CP ey or your CP chp. It is embedded in We and Reade West to make it better for group break. The function of CP grouping is the same as the Reade and Wee of TAG and Reade.

The function of CP in the 200510002156.4 and your "Life Method" and 200610065663.7 and your "Methods in CP" are in the full text of this article, reference to 200510002156.4 and your "Life Method" And 200610065663.7 and your "in CP" method in the CP other wood program content and not in this one.

CP ey is stored in CP ey in the intersection of 佰 and Yu and control.

The preferred 64b (8B) packet resilience can be sufficient for AES ES and other packet breaks. Better packet breaks Better CP packet breaks CP 98b 2B) The crack is better than your 48b (6B)

The CP group is in place in 200510002156.4 and your "Yusheng Method" and 200610065663.7 and in your "In the Method of CP", some of which refer to 200510002156.4 and your "Life Method" And 200610065663.7 and your "in CP" method in the CP other wood program content and not in this one.

The inverse of the inverse shift register and the control of the control are reversed. The contents of the bit register are grouped, signed, etc.

There is a special foot card in the wood, but the footsteps of the TAG Reade, but the foot and the foot in the way of the WE Reade, there is not much of her, and all of them, such as, and so on, rely on group breaks, especially CP Group breaks and all are in smart We or Reade. CP grouping is easy to sign the signature of the CP signature. Signatures can be signed differently from 2 to 200 seconds, and the cost of CP is only ten yuan. CP signature wood improves the security of the system.

The anti-shift register of the CP signature is stored in the TAG as shown in Table 2.

2 reverse shift register occupied in TAG

Traffic r2 2 3 T3

6B 5B 6B 5B 6B 5B Signature 8B 8B 8B Controls the amount of traffic that is sufficient for grouping and resting. The special TAG and the secrets of the TAG and any secrets are only known by W e and Reade and the security of the ancients.

Better inverse shift register multi-reverse division

The signature of the inverse shift register is changed.

The inverse control of the shift of the sex inverse shift register 1 and the 32nd must have at least 1 of 2 to 31 levels.

8 control of the anti-shift register control

It is better that the input of the anti-shift register of the TAG in the TAG is not full. The input of the anti-shift register is not reversed in the near period.

There is a register and control in a TAG. The control is equal to (23 8 ) 3 2 1034 and the same meta R device does not exist. The frequency of the frequency device is more effective to prevent the possibility of using the crime.

Signature and dense in the device are stored in CP ey without CP ey method and line solution, 佰 and Yu To the purpose of system security.

CP ey and to each Wte operation and each Reade operation operation to insert CP ey for operation is beneficial to the event and the benefit of life.

At the end of the work, CP ey CP ey was pulled out and kept small. The operation of the WE operation and the Reade operation without CP ey does not require special operations and management. Input methods and methods effectively prevent the possibility of using the same crime

Here's the security of her and the meta system. The card includes three inter- versatile anti-shift registers SR and SR SR respectively controlling the TAG, 佰, and 敬.

The inverse inverse shift register SR, which is controlled by the signature of the inverse inverse shift register S than the signature controlled by W e 佰

The residual inverse shift register SR controls the signature of the Reade remainder.

Sexual shift register SR shift together

Sexual inverse shift register S ratio shift 佰 together

The shift of the inverse inverse shift register S is shown together as shown in 2.

The inverse or shift register of the s or s or s and s are respectively shifted to the end of the operation.

The content of the preferred TAG neutral anti-shift register cannot be input by the outside world. The content signature of the anti-shift register is still causing the inverse of the shift register, its content, and the biosignal signature is also generated by the signature 1 E ep e signature

Where the SG foot signature is e ep e full signature g The signature + SR indicates that the TAG and the contents of the memory are not bundled. The SG signature is signed by the CP and is executed by CP - ey.

Better signature, signed by CP, with CP

98b 2B) Its crack is still in your 48b (6B) by CP ey.

W e 签名 Signature SG. , daa+ + SR ) g 2 where SG foot signature with W e foot signature g

佰 daa's signature daa+ + SR means that the sum of the 反 daa and TAG and the anti-shift register contents S are not bundled.

SG signature is signed by CP ey with signatures that can be grouped by AES S and other gods.

Better signature, signed by CP, with CP

98b 2B) Its crack is still in your 48b (6B) by CP ey.

Reade residual signature S de

The SG foot signature is the signature of the Reade' foot. The signature of the daa daa+daa2+ + S indicates that the remaining daa2 and TAG, 佰 daa, and the contents S of the memory are not bundled.

SG signature signed with CP, to be executed by CP - ey

Better signature, signed by CP, with CP

98b 2B) Its crack is still in your 48b (6B) by CP ey.

It includes the control of the control inverse shift register and the control of the inverse inverse shift register.

Better control of the first 32b anti-shift register 32 anti-one if the foot 1 reaction if the foot 0 does not work.

The control of B 8b is decisive for the inverse shift register.

The content of the controlled 佰 and 1 and the 32nd fixed force 1 of at least 30 1 8b cannot be all 0s.

Control the CP to get 5 6B48b, ie E3 = will

TAG.

Inside TAG To solve the problem.

In the case of W e and Reade, 3 nn, where E means that the rest of the game can be used by AES ES, etc., and all of them are used in CP ey.

Preferably, the group used, the break, the CP, the group, the CP, the CP.

98b 2B) Its crack is still in your 48b (6B) by CP ey.

Better line signatures are not free even if they are cracked.

The following is a description of the security of the metasystem. The method is provided by a ac e and TAG.

3 shows the security of the system and the method of the following steps: Step S 0 through CP ey using group break method to be safe

Inserting CP ey into W e using CP grouping, the control generated by the handoff is signed and signed.

OTHER in the TAG

Step S 0 uses CP to generate signature g control

The rest of each W e is provided in the TAG as follows. Step 110 W e First the inverse inverse shift register in the TAG SR uses the W e signature inserted into CP ey ie p,e- + SR) g

The SG foot signature is signed by e ep Se foot + SR footed anti-shift register bundled g foot signature.

SG signature signed with CP, to be executed by CP - ey

CP 98b 2B) its crack is still in your 48b 6B) Step S120 Management Center C) dense, 3 all CP ey which is in the rest of the 。.

Step S130 is generated for each element TAG. Where E3(m) where Yu Nai Yu Yu Yu.

Step S140, the amount of control of the signature g, and

Other W e or W e are provided in the TAG.

Step S200 embeds CP ey into W e and Reade West to make it have the function of CP. The security in the W e TAG secures the rest of her Reade TAG to secure her.

Embed CP ey in W e and Reade West to make it CP-enabled. W e 安全 Safe her Reade

In the rest of the line, she can use the same Reade and We as TAG and Reade.

For a single W e, it can operate with multiple names. Each operation has CP ey. Only the CP ey of the insert operation can operate. The operation of the operation is in W e .

In step S200, the line in the W e TAG secures her. Including the following steps

Step S211 W e utilizes the uniqueness of CP ey TAG

SG

The SG is sufficient to use CP to perform CP 98b 2B by CP ey. The crack is in your 48b (6B). In the CP system, the name is g + SR if g g.

If there is more than 佰, then the remaining steps include step S212 and step S213.

Step S212: If the rest of the TAG is obtained by using the remaining line solution, that is, e2 2

Which means that the code is sufficient for the daa foot.

The rest of the work can be done by a group of gods such as AES ES, all used, all in CP ey.

CP 98b 2B) Its crack is still in your 48b (6B) Step S213 W e TAG

which is

Where SG is enough to use CP to perform CP 98b 2B by CP ey). The crack is still in your 48b (6B)

The g g of the foot is sufficient if g g is.

Step S214 W e TAG 佰 causes

And the shift operation of the sex inverse shift register in the TAG W e

TAG Neutral Inverse Shift Register FSR2 佰 CP ey CP Completion Line Signature SG n,1 aa+ + SR) g 2

Where the SG foot signature is signed by W e

佰 daa's signature daa+ + SR indicates the bundle of 佰 daa and TAG's contents FS.

The SG signature is signed by the CP and executed by CP-ey.

Step S215, using the W e TAG CP CP ey using the packet vacancy method, that is, E (daa ) code

Where E is the daa foot 佰 code foot.

The groupings used can be enough for AES ES and other gods to work, all used, all in CP ey.

It is better to use the AES/ES group.

The operation of 佰 is in the unique, 佰 daa , the remainder daa2 , the sexual inverse shift register SR in step 214 W e

TAG 佰 then shift operation of the inverse shift register S 佰 CP ey uses group breaks, line signature, and the following steps

Step S2141 W e and the command or the inverse inverse shift register S operation

Step S2142 W "e accepts the TAG output of the sex inverse shift register FSR, the pre-existing control of the genie W e will be 2 3 of the first 30 inverse shift register SR Anti 8

Step S2143 W e and the sex inverse shift register SR go on 1 2

Step S2144 TAG output 佰 da

Step S2145 W e on top 佰 daa

Step S2146 W e and one out. 0..31

Step S2147's sexual inverse shift register S is 5 b more than the output

Step S2148 W e 5 b If then 2 (2 0..31) Step S2149 The inverse of the shift register S is output 5 b

Step S21410 W e If then 3 3 0..31)

Step S21411 My My Inverse Shift Register SR Output 3 of 5 b

If everything is there, go to the next step or exit.

Step S2141's sex inverse shift register FSR2 on 2

3 4 Add the 佰 of the 得到 to get the added 佰 S

Step S21413 W e 佰S signature added on 4

Step S21414 W e in the signature g TAG in step S21415 TAG the sex inverse shift register on 1

twenty three .

Next 3 TAG and 3

W e just signed on 5 on 4. Before the air and the 1, 3, 5, etc., they are not signed, but the signatures are 2, 4, 6, etc.

The amount of control that is sufficient to control the amount of traffic is not in this case. For Reade, it can be more Reade. The CP ey Reade operation is still inserted.

Step S2, the remaining line in the Reade TAG, her include and signature, etc.

Step S221 Reade uses the CP ey TAG

Ie e ep + SR) g

The same as W e in step S211 of Reade is therefore not described one by one.

Step S222 If TAG is used by 佰

Reade TAG 佰佰佰 CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP Read Read Read Read Read Read Read Read Read Read Read Read Read Read The groupings used can be sufficient for AES S and other gods to be grouped or CP to be used for rest, all used, all in CP ey.

Step S223 Reade gets 佰, ie S '.

" daa+ + SR ) g

Where SG is sufficient to sign the foot CP with the g 2 foot of the CP ey w e foot if g 2 g .

Step S224 Reade TAG

That is, S 'ea , (daa2+daa+ + SR3 g 3

Where SG is enough to take CP to the foot of CP ey eade

佰daa, saver SR3 if

then.

Step S225. The remaining operation in the Reade TAG and the shift operation of the inverse shift register. CP ey The remaining line signature is SG de daa2+daa+ D+ SR3) g 3

The SG foot signature is daa2 with a new ember xa, The new register SR is signed by its own eade'. The signature will be signed in the TAG in CP ey.

Signature signed with the foot CP.

Step S226 remaining if the remaining in the TAG

Then the remainder of the CP ey is solved by using the grouping method. 2code2 daa2

Among them is the code 2 remaining daa in the Reade TAG. Operate in CP ey.

Step S227 If a new balance is needed, CP ey uses the packet to take the TAG.

Where R is added to the code of the daa2 secret. Operate in the code TAG in CP ey.

In step S225, the shift operation of the inverse shift register is performed. CP ey remaining signatures include the following steps.

Step S2251 Reade and the command or the remainder of the inverse shift register shift operation

Step S2252 Reade accepts the TAG output of the inverse inverse shift register S and the 3 Reade of the control, and the 3 30's first 30 inverse shift register SR is inverted 8.

Step S2253 W e and the sex inverse shift register SR on 1 2

Step S2254 RF TAG output remaining daa

Step S2255 Reade on 2

Step S2256 Reade and out one. 0..32

Step S2257 Sexual Reverse Shift Register S Output 5 Steps S2258 Reade If and then 2

Step S2259's sexual inverse shift register S is 5 more than the output b

Step S22 0 Reade If and then 3

Step S22 1 of the sex inverse shift register SR output 3 of 5 b

If 3 then the next or exit.

Step S22 2 of the sex inverse shift register S on 2

3 4 The result of the operation is obtained S 3 Step S22 Reade S signature on 4

Step S22 4 Reade moves the sexual inverse shift register FS of the step S22 TAG in the signature g TAG by 1 on the 1st and then the next inverse 3 . The shifting operation of any change, , and the same anti-shift register of the s, y, y, and sheng makes the contents of the signature and the signature of the birth. Signature enough to rely on the shifting of the inverse shift register SR. The shifting operation of the operator is required to change the signature. The legal operator has the ability to have a new signature, but the illegal operator has no new signature. .

This and the P-signed signature of the meta-system are safe and effective.

In this and the description of the R system, the shift control of the anti-shift register of the anti-shift register is prohibited. If the content of the anti-shift register is not possible or not, then it can be prevented. The medium embryo considerations and Mingtong use CP ey to solve the problem by using group breaks to secure her.

This can be seen that this and the effective completion of the general security she is using the same step in the analysis of the next step and whether it can resist Gho and fools and anatomy.

The fool has the same difference and only the anti-shift register. Input from the outside world. Can the fool have the same legal card?

First 佰1000

It will be on the fool card, that is, the summer, the operator's signature, and the control of the inverse shift register.

The same will be the 佰 and the rest to the fool card.

The inverse shift register control is not sufficient. The inability to solve the control is not necessarily the next step.

If you want to get the control of the inverse shift register, you must dissect it. If you control it, you can get a legal fool of 1000. If it doesn't, it doesn't work even if it is dissected. Therefore, it is safe to keep the control of the inverse shift register.

It is easy to combine this and other aspects of this and the special aspects of the wood man.

The above and the rest are not used for this and the restrictions and requirements.

Claims

Request phase

1, the system includes the device and the device and respectively include, 佰 and

The s, s, and s, respectively, 3-segment inverse shift register system including CP ey, which is embedded in the sigma, and has the function of grouping and CP signature.

CP ey is separate from Yu and Yu and controlled

The inverse of the inverse shift register is controlled by the control of the inverse shift register. The metasystem of requirement 1 is characterized by one of the grouping of AES or ES grouping.

3. The metasystem of requirement 1 is characterized by the fact that the CP is in full swing and its 98b

4. The metasystem of any of claims 1 to 3 is characterized by a special inverse shift register 32 inverse shift register.

5. The metasystem of requirement 4 is characterized by the division of the anti-shift register and the multi-reverse signature of the inverse shift register.

6. The metasystem of requirement 5 is characterized by the control of the control of the inverse inverse shift register.

7. The metasystem of requirement 1 is characterized by the fact that the inverse of the shift register is not full.

8. It is characterized in that it includes three inter-reverse anti-shift registers that control the TAG, 佰, and Yu.

The first inverse shift register is controlled by the signature

佰 The second sex inverse shift register controls the signature of 佰

The remaining third inverse shift register is controlled by the remaining signature.

9. The element of requirement 8 is characterized by the shift of the first-order inverse shift register.

Second-order inverse shift register shift 佰 together

The shift of the third-order inverse shift register is left together.

10, the requirement of 8 or 9 yuan, including control

The control of the inverse of the shift register and the control of the inverse of the shift register.

11, the requirement of 10 yuan is controlled by the control of the first 32b anti-shift register 32 anti-one if the foot 1 reaction if the foot 0 does not work

Controlled 8b decisive inverse shift register

The control 的 but the control 1 and the 32nd fixed force 1 of 30 contain at least one 18b content cannot be all zeros.

12, the system's security method is characterized by the following steps

Step A through CP ey using grouping and signature features and signatures

Step B embeds CP ey and West to make it safer for her in the group's function and the function of the CP.

13. The method of requesting the security of the system of 12 is characterized by the following steps: Step A includes the following steps

Step A inserts CP ey into the traffic control using the CP group to control the amount of traffic control. The third secret is obtained. The signature is obtained by signing the amount of traffic, the amount of traffic, and the signature.

14. The safety of the system of claim 13 is based on the following steps: Step A uses the CP to generate the signature control volume and the amount of addition.

The first anti-shift register in step A uses the signature inserted into CP ey Step A12 is dense in all CP ey, which is in the rest of

Step A13 is generated for each element. Where ,) where m is

Yu Yu Yu Yu

Step A14 will control the amount of the intersection, and the TAG will provide the other.

15. The security method of the metasystem of any one of 12 to 14 is characterized by the security in step B. She includes the following steps: Step B: Using CP ey to pass the packet method of the TAG

Step B12 TAG 佰 causes the shift operation of the neutral inverse shift register. First, the second-order inverse shift register 佰 CP ey uses CP to perform the line signature

In step B13, the CP ey uses the packet method.

16. The security of the system of claim 15 is based on the same method. Step B and step B12 are the same.

Including the following steps

Step B 1 If the remainder is used, the remaining line is used to obtain the remainder.

The remainder obtained in step B2.

17. The method of claim 15 is to secure the method. The special method is the shift operation in step B 2 and the second inverse shift register.

CP ey uses group breaks to sign the line, including the following steps

Step B 21 and the command or

Second-order inverse shift register operation

Step B122 accepts the output of the second inverse shift register before the first 以及 1 and the controlled r2 will 3 ( ) 2 of the first 30 second reverse shift register reverse 8 Step B123 and the radio frequency second anti-shift register go on 1

2

Step B124 Output 佰 da

Step B125 on 2 佰 daa

Step B126 and one of them 3

The 5 b of the second-order inverse shift register output of step B127 is answered. Step B128 cast 2

5 b of the second-order inverse shift register output of step B129. Steps B 210 and 3

Step B 211 of the second sex inverse shift register SR output 3 5 b force answer

The second polarity inverse shift register of step B 212 is on 2

4 Add the 佰's 佰 to get the added 佰 S 2

Step B 213 adds the 佰 S signature SGw on 4. , S ) g

"

Step B 214 will be signed in g

Step B 215 of the sex inverse shift register on 1 2

3 .

18. The security method of the metadata system of any one of 12 to 14 is characterized in that the remaining line in the radio in step B is safe. The method includes the following steps: Step B21: Using CP ey to pass the group and CP method

middle

Step B22: If the 佰锋 front uses the TAG TAG 佰佰 CP CP CP CP CP CP CP CP CP

Step B23 Reade Get 佰

Step B24 Reade TAG

The remainder of the operation in step B25 and the shift operation of the inverse shift register are used by CP ey to perform the signature of the remaining line.

19. The safety of the metasystem of claim 18 is based on the following steps: Step B26 If there is any remaining, then the remainder of the CP ey will be solved by the group break first.

Step B27 If a new balance is required, CP ey uses the group break.

20. The method of claiming the security of the metasystem of 17 or 18 is characterized by the shifting operation of the neutral inverse shift register in step B25. CP - ey uses the packet break, the signature of the remaining line includes the following steps.

Step B251 and the command or

Third-order inverse shift register shift operation

Step B252 accepts the output of the third-order inverse shift register before the first 以及 1 and the control of the 3 (3) of the first 30 third-order inverse shift register

Step B253 and the third polarity inverse shift register on 1

2

Step B254 Output the remaining daa2

Step B255 on 2

Step B256 and out one of them 0 3

Step B257 of the sexual inverse shift register SR2 output 5 b to answer the answer Step S2258 Reade and

Step S2259's sexual inverse shift register SR2 output 5 b to answer the answer Step S22 0 Reade and 3

Step S22 of the sexual inverse shift register SR2 output 3 5 b force response.

Step B256 and the third polarity inverse shift register on 2

3 4 more operations get the result of the operation S

Step B257 S signature on 4

Step B258 will be signed in g TAG

The third-order inverse shift register of step B259 goes 2 on 1 and then goes to the next.