CN105959098A - Format-reserved encryption algorithm based on multi-segmented Feistel network - Google Patents

Abstract

The invention relates to a format-reserved encryption algorithm based on multi-segmented Feistel network, and the algorithm comprises the following steps: according to the inherent format of a plaintext space, the plaintext space is divided into t parts: S1, S2, ..., St; wherein the size of the set is n; a secret key k used by round times and round function of a Feistel network, wherein the round times r is an even number related to a partition number; given plaintext m can be formatted as shown in the description; x1, x2,..., xn serve as t inputs for partitioning Feistel network, or the inputs can be recorded as (x1, x2, ..., xt); r round operation is executed, and the final output cryptograph is as shown in the description; the advantages of the algorithm are that: sensitive data is segmented, different segmented range is defined, self-defined pseudorandom function, modular addition and modular minus operation are adopted, the Feistel network is adopted to execute round operation of even number, so that the encryption which can reserve the format can be realized, a numeric data encryption scheme which can reserve any given format can be supported, the data and database cannot be influenced after the encryption, and a possibility of the numeric personal identification information encipherment protection in a database application system in the prior art can be provided.

Description

Reservation form AES based on multi-split Feistel network

Technical field

The invention belongs to field of data encryption, be specifically related to a kind of numeric type encryption method retaining any given form, The method can application in needing the environment (data base, network, smart card virtual machine etc.) being encrypted sensitive information.

Background technology

The fast development of the Internet so that the sensitive data in storage medium (data base, mobile device, smart card etc.) is more The most easily to be stolen, basic reason is that they still use mode in plain text to the storage of these sensitive datas, and encrypts It it is the most effective mode strengthening the sensitive data safety stored.Sensitive data often comprises the set form of self, example Such as identification card number, bank's card number etc..But traditional AES, such as AES, 3DES etc., all can destroy the form of data so that Data after encryption cannot store in original data base or node, and can destroy the function of existing operation system.As The encryption of these information is not the most destroyed its intrinsic form, to guarantee that existing operation system, database store structure to the greatest extent may be used by what The change that energy is few, is a problem that have to solve.

Summary of the invention

The present invention seeks to solve traditional AES and can destroy the form of data so that the data after encryption cannot be The problem of storage in the storage mediums such as original data base, mobile device or smart card, it is provided that the reservation of a kind of sensitive data Form encryption method.

The present invention for achieving the above object, is achieved through the following technical solutions:

Reservation form AES based on multi-split Feistel network, the method comprises the steps:

1.1. by plaintext spaceSIt is divided into according to its intrinsic formtPart:S ₁ , S ₂ , … ,S _t .Wherein remember setS _i Size Forn _i 。

1.2. the wheel number of times of Feistel network is setrThe key used with round functionk, wherein take turns number of timesrFor with segmentation NumbertRelevant even number；

1.3. for given plaintextm, formatted expression:m =x ₁ || x ₂ || … || x _t , wherein:x ₁ ∈S ₁ , x ₂ ∈S ₂ ,… ,x _t ∈S _t ；Willx ₁ , x ₂ , … ,x _n AstSegmentation Feistel networktIndividual input, or remember that input is。

1.4. performing the wheel computing of r wheel, the ciphertext of final output isc =y ₁ || y ₂ || … || y _t , wherein:y ₁ ∈S ₁ , y ₂ ∈S ₂ ..., y _t ∈S _t 。

Wheel computing in 1.4:

2.1. segmentation Feistel network operations is taken turns for each, if input is:

Then it is output as:

First pass through pseudo-random permutation function

WillPass throughFIt is mapped toOn.

If 2.2.S _i Size ben _i , then can be byS _i It is considered as ring, thenFFor by this, to take turns encryption key well-determined On displacement:

。

2.3. random permutationFThe standard encryption methods such as AES/DES can be used, encrypted result is being carried out corresponding modular arithmetic ?.

The mould used in 2.1 adds computing:

3.1. mould adds computingResult belong to set, above-mentioned mould adds computing abstract representation and is:

The most right, have

Further, still can be byS _i It is considered as ring, thus

3.2. mould adds computingDetailed process (here withAs a example by):

The most in following manner, respectively willWithIt is embedded intoUpper:

,。

Specifically, as,；

B. the above results is existedIn carry out additive operation (being addition of integer), i.e. existIn carry out additive operation:

C. willMiddle element carries out mouldComputing, obtainsIn result, such as:

In sum, complete mould to add。

In this example, it is specially,。

It is an advantage of the current invention that: by by sensitive data segmentation the codomain that defines different segmentation, using self-defining Pseudo-random function, Mo Jia and mould subtract computing, use Feistel network to perform the wheel computing of even number round, to realize retaining form Constant encryption, can support to retain the numeric type data encipherment scheme of any given form, does not affect data and data after encryption The compatibility of storehouse, node and operation system, for the encipherment protection of numeric type personally identifiable information in the application system of data with existing storehouse Provide possibility.

Accompanying drawing explanation

Fig. 1 is that I type t of the present invention splits Feistel AES schematic diagram.

Detailed description of the invention

Reservation form AES based on multi-split Feistel network of the present invention comprises the steps:

1. a sensitive cleartext information is divided, according to its given format, be divided intotIndividual data segment.That is, by plaintext spaceSIt is divided into according to its intrinsic formtPart:S ₁ , S ₂ , … ,S _t .So,SJust can be expressed as:

Wherein, if note is gatheredS _i Size ben _i , the most further can be bySIt is expressed as:

2. determinetThe wheel number of times of segmentation Feistel networkr, and the key that every round function is used

,

Wherein take turns number of timesrFortEven-multiple；

3. useRepresent a legal sensitive data, wherein:x ₁ ∈S ₁ ,x ₂ ∈S ₂ ,… ,x _t ∈S _t ；The most respectively willx ₁ , x ₂ , … ,x _n AstThe segmentation Feistel network first roundtIndividual input.

4. perform the wheel computing of r wheel: if a certain input taken turns is

Then it is output as:

,y ₁ ∈S ₁ , y ₂ ∈S ₂ ..., y _t ∈S _t

According to Fig. 1tSegmentation Feistel network,It is:

The most each take turns used dynamic analog and add the result of computing and belong to set, above-mentioned mould adds computingAbstract representation is:

The most right, have

Further, can be byS _i It is considered as ring, thus

6. mould adds computingDetailed process (here withAs a example by):

The most in following manner, respectively willWithIt is embedded intoUpper:

,。

Specifically, as,；

B. the above results is existedIn carry out additive operation (being addition of integer), i.e. existIn carry out additive operation:

C. willMiddle element carries out mouldComputing, obtainsIn result, such as:

In sum, complete mould to add。

In this example, it is specially,。

The basic concepts relevant with data encryption that the present invention relates to:

(1) block cipher: block cipher be by clear-text message coded representation after numeral (be called for short in plain text numeral) sequence, be divided into The packet (can regard the vector of a length of n as) of a length of n, each packet is transformed into isometric output the most under the control of the key Numeral (being called for short ciphertext numeral) sequence.

(2) 3DES:3DES(or referred to as Triple DES) it is triple DEA (TDEA, Triple Data Encryption Algorithm) common name of block cipher.It is the equal of that each packet is applied three des encryptions calculate Method.Due to the enhancing of Computing ability, the key length of master DES password becomes easily by Brute Force；3DES is i.e. Be designed to provide for a kind of relatively simple method, i.e. by increase attack that the key length of DES avoids being similar to rather than Design a kind of brand-new block cipher.

(3) AES: the Advanced Encryption Standard (Advanced Encryption Standard, AES) in cryptography, is beautiful A kind of block encryption standard that federal government of state uses.This standard is used for substituting original DES, has in many ways been analyzed and extensively Used by the whole world.Through the selection flow process of 5 years, Advanced Encryption Standard was by National Institute of Standards and Technology (NIST) it is published on FIPS PUB 197 November 26 calendar year 2001, and becomes effective standard on May 26th, 2002.2006 Year, Advanced Encryption Standard becomes one of most popular algorithm in symmetric key encryption already.

(4) Feistel network: Feistel network is a kind of symmetrical structure for block cipher design.A lot of password marks Standard all have employed Feistel structure, including DES.The advantage of Feistel is: owing to it is symmetrical cryptography architecture, So the most very much like to the encryption of information and the process of deciphering, the most just the same.This allows for during implementing, right The requirement of encoding amount and line transmission just decreases almost half.

(5) pseudo-random permutation function: in computer, communication system use random number, random code be pseudo random number, Pseudo noise code.So-called " random code ", it is simply that no matter this yard has the phenomenon how long circulated all without appearance, and " pseudo noise code " exists Can start the cycle over from its first when code length reaches to a certain degree, owing to the length of the cycle occurred is quite big, such as CDMA uses The pseudo noise code of 42, the probability of repetition is 4.4 part per trillion, it is possible to use as random code.

The segmentation of the sensitive information with specific format represents

The segmentation of the sensitive information that the present invention provides is expressed as follows:

One sensitive information is divided into t data sectional by its feature:, each data sectional is by having phase Form with the numerical value of data characteristics, can express with an integer finite field.

Such as, the ID (identity number) card No. of legal 18 can be divided into seven parts: , represent area code, year of birth, the birth moon, date of birth, sequence code and check code respectively.Wherein, the character length of every part is: 6、4、2、2、3、1；The codomain of every part is: S₁={0, …, 999999}, S₂={1900, …, 2050}, S₃={1, …, 12}, S₄={1, …, 31}, S₅={1, …, 999}, S₆={0, …, 9, ‘X’}。

The encryption method retaining form based on t segmentation, as a example by ID (identity number) card No., is described in detail by the present invention.

AES:

The first, the ID (identity number) card No. of legal 18 is divided into six parts:, point Do not represent area code, year of birth, the birth moon, date of birth, random number and check code.Wherein, often part is a length of: 6,4, 2,2,3,1；The codomain of every part is:S ₁=0 ..., 999999}(ignores the meaning of area code here, is considered as being 0, ..., 999999 set constituted),S ₂={1901, …, 2050}, S ₃={1, …, 12}, S ₄={0, …, 31}, S ₅ ={1, …, 999}, S ₆={0, …, 9, ‘X’}；WhereinS ₆Value can by first five part use check code computing and Draw, but herein for convenient narration, it is assumed that it is independent with first five part.

UseRepresent a legal ID (identity number) card No., wherein:x ₁ ∈S ₁ ,x ₂ ∈S ₂ ,… ,x ₆ ∈S ₆ 。

The second, in order to ciphering process is described, set I type 6 and split the wheel number of times of Feistel networkrThe actual application of=6(is taken turns Number of times is the multiple of 6, and needs to take turns more than 6), and random permutation functionFThe key needed。

3rd, willAs the input of Feistel network, perform altogetherrThe wheel fortune that=6 take turns Calculate:

The first round:

Second takes turns input is, the rest may be inferred.

4th, complete the 6th take turns after, obtain one isometric with input and have the output of same format, wherein:y ₁ ∈S ₁ , y ₂ ∈S ₂ ..., y ₆ ∈S ₆ ；

5th, decrypting process and the 3rd encryption are contrary, willAs input, perform altogetherr=6 take turns Wheel computing:

The first round:

Wherein e isInverse operation；

Second takes turns input is, the rest may be inferred.

Specifically perform process:

Ciphering process:

Input ID (identity number) card No. is 370722196304091511 in plain text, in conjunction with above Definition, its obtaining actually entering formats statement:.Here random permutation functionAdopt Use standard AES encryption, if plaintext space is, then encrypted result is carried out mouldOperation so that displacement result still falls within。

------------------------r=1 (first round)------------------------

Input:, wherein:

Calculate:

,

Output:

------------------------r=2(second takes turns)------------------------

Input:

Calculate:

,

Output:

-----------------------r=3(third round)------------------------

Input:

Calculate:

,

Output:

-----------------------r=4(fourth round)------------------------

Input:

Calculate:

,

Output:

-----------------------r=5(the 5th takes turns)------------------------

Input:

Calculate:

,

Output:

-----------------------the r=6(first round)------------------------

Input:

Calculate:

,

Output:

Finally it is reduced to identification card number form obtain:

I.e.。

Decrypting process:

Input ID (identity number) card No. ciphertext is 370903202306042605,

-----------------------the r=1(first round)------------------------

Input:

Calculate:

,

Output:

-----------------------r=2(second takes turns)------------------------

Input:

Calculate:

,

Output:

-----------------------r=3(third round)------------------------

Input:

Calculate:

,

Output:

-----------------------r=4(fourth round)------------------------

Input:

Calculate:

,

Output:

------------------------r=5(the 5th takes turns)------------------------

Input:

Calculate:

,

Output:

------------------------the r=1(first round)------------------------

Input:, wherein:

Calculate:

,

Output:

Finally it is reduced to identification card number form obtain:

Obtain 370722196304091511.

Claims (3)

1. reservation form AES based on multi-split Feistel network, it is characterised in that: the method comprises the steps:

1.1. by plaintext spaceSIt is divided into according to its intrinsic formtPart:S ₁ , S ₂ , … ,S _t , wherein remember setS _i Size ben _i ；

1.2. the wheel number of times of Feistel network is setrThe key used with round functionk, wherein take turns number of timesrFor with segmentation numbert Relevant even number；

1.3. for given plaintextm, formatted expression:m =x ₁ || x ₂ || … || x _t , wherein:x ₁ ∈S ₁ , x ₂ ∈S ₂ ,… ,x _t ∈S _t ；Willx ₁ , x ₂ , … ,x _n AstSegmentation Feistel networktIndividual input, or remember that input is;

1.4. performing the wheel computing of r wheel, the ciphertext of final output isc =y ₁ || y ₂ || … || y _t , wherein:y ₁ ∈S ₁ , y ₂ ∈S ₂ ..., y _t ∈S _t 。

2. reservation form AES based on multi-split Feistel network, it is characterised in that: the wheel computing in 1.4:

2.1. segmentation Feistel network operations is taken turns for each, if input is:

Then it is output as:

First pass through pseudo-random permutation function

WillPass throughFIt is mapped toOn;

If 2.2.S _i Size ben _i , then can be byS _i It is considered as ring, thenFFor by this, to take turns encryption key well-determinedOn Displacement:

；

2.3. random permutationFThe standard encryption methods such as AES/DES can be used, encrypted result is being carried out corresponding modular arithmetic i.e. Can.

3. reservation form AES based on multi-split Feistel network, it is characterised in that: the mould used in 2.1 adds computing:

Mould adds computingResult belong to set, above-mentioned mould adds computing abstract representation and is:

The most right, have

Further, still can be byS _i It is considered as ring, thus

；

3.2. mould adds computingDetailed process (here withAs a example by)；

The most in following manner, respectively willWithIt is embedded intoUpper:

,；

Specifically, as,；

B. the above results is existedIn carry out additive operation (being addition of integer), i.e. existIn carry out additive operation:

C. willMiddle element carries out mouldComputing, obtainsIn result, such as:

In sum, complete mould to add；

In this example, it is specially,。