CN101848079A - Perturbation method and encryption method for character-oriented sequence with memory - Google Patents

Abstract

The present invention relates to a kind of character-oriented, the sequence perturbation motion method with memory and encryption methods, belong to information processing and transmission field. Its perturbation motion method are as follows: 1) preset 2m memory unit and assign initial value; 2) each word xi of input is successively carried out: a) takes the value h of xi high m bit; If the content yh of h unit, output word ; B) the value t of the low m bit of xi is taken; Content yt exclusive or by xi through S box transformed value and t unit, as a result updates yt; By updated yt through S box transformed value and yh exclusive or, yh is as a result updated; 3) using the word zi being sequentially output as the key stream sequence after upsetting. This encryption method are as follows: 1) message sender generates key stream; Then it by itself and origination message step-by-step exclusive or, encrypts origination message and sends it to message receiver; 2) message receiver generates key stream; Then itself and the encryption message step-by-step exclusive or received, decryption encryption message obtain origination message. The present invention improves encryption software and realizes speed, and safety is stronger.

Description

A kind of sequence perturbation motion method and encryption method towards word, band memory

Technical field

The present invention relates to the method for a kind of message transmission and processing, relate to a kind of sequence perturbation motion method and encryption method or rather towards word, band memory.Employing is based on the mixed type band memory logic of whole word operation, with the anti-analytic intensity of enhancement sequences cryptographic algorithm.

Background technology

Cryptographic technique is with a long history; be used for the military and diplomatic correspondence safety of protection at first, still, along with popularizing of communication network and computer network; the application of contemporary cryptology no longer is confined to politics, military affairs and diplomatic, and its commercial value and social value have obtained approval widely.Maintaining secrecy is cryptographic core, is the utility that acquired information is maintained secrecy and encrypt.

Cryptographic algorithm is divided into public key algorithm and private key cryptographic algorithm.The private key cryptographic algorithm is divided into block cipher and stream cipher algorithm again.Block cipher generally carries out block encryption to message, and a bigger message blocks is once encrypted in the algorithm operation.Stream cipher algorithm generally with the key of a weak point, with specific key stream generating algorithm, generates and the suitable key stream sequence of message-length that will encrypt, key stream sequence and plaintext step-by-step XOR is reached the purpose of encryption.And deciphering side generates same key stream sequence, with the ciphertext XOR, can obtain expressly.So the key of stream cipher algorithm is a design safety key stream generating algorithm fast.Traditional every operation of key stream generating algorithm once only produces the key stream of a bit.

To the attack of stream cipher algorithm, mainly be the safety defect of seeking the key stream sequence at present, reach the recovery encryption key, or key stream sequence and true random sequence are distinguished, or attempt generating the purpose of key stream sequence.Main attack method has algebraically to attack, distinguish and attack, guess and determine attack, correlation attack, differential attack etc.From design angle, what be difficult to resist most is to distinguish to attack, and to this analysis based on statistics of stream cipher algorithm, its success or failure depend on the design of key stream sequence formation logic to a great extent.

The present technique field generally believes, adopting band memory logic in the cryptographic algorithm is to strengthen a kind of basic measures of key stream formation logic, it can enhancement algorithms resist the linear performance of distinguishing attack and difference analysis, therefore is with the reasonable utilization of memory logic to be likely the optimal selection that the opposing differentiation is attacked.

Along with the high speed development of communication network and computer network, the key stream generating method that traditional operation once generates a bit can not satisfy needs, especially the software realization aspect on the realization speed.Some word-oriented key stream generating methods are devised gradually.I.e. operation once generates the key word of some bits, forms the key stream sequence by key word.For example SNOW3G algorithm, Rabbit algorithm.

In stream cipher algorithm design, whole word band memory logic has been become in recent years main flow design philosophy as the nonlinear transformation assembly.Make a general survey of disclosed at present stream cipher algorithm, the application of whole word band memory logic begins to take shape, and shows a variety of whole word memory forms.For example: the RC4 algorithm be in fact a kind of be the algorithm of core to stir the whole word band memory of type logic.The so-called finite automata that is adopted among the SNOW comes down to a kind of whole word band memory of the type that adds up logic of complexity.

Patent CN1829142A has invented a kind of new " is the sequence upset method of feature based on byte manipulation, with the band memory ".This method allows the key stream sequence be unit with the byte, by behind the disarrangement device with the byte being unit output again.This disarrangement device is that a whole word band of strengthening character string is remembered non-linear logic, has the feature that stirs type and add up type band memory logic concurrently.It is characterized in that comprising:

Steps A presets 2 ^mIndividual mnemon, 0,1,2 ..., 2 ^m-1, deposit a byte content in each mnemon;

Step B is to the byte sequence of input x=(x ₀, x ₁...) in each byte x _i, be done as follows:

A) get x _iThe value h of high m bit, h is less than 2 ^mValue;

B) behind known h, with the content y in h the mnemon _hWith input byte x _iCarry out xor operation, the byte z of output after upsetting _i, promptly

C) upgrade mnemon, take out h the content y in the mnemon _hThe value t of low m bit, t also is less than 2 ^mValue.Behind known t, with the content y in h the mnemon _hBe updated to

With the content y in t the mnemon _tBe updated to

Promptly

Wherein S represents a non-linear function transformation, is a displacement from the byte to the byte.

The value of described m is 3 or 4 or 5 or 6.

The sequence upset method of this invention when design is remembered logic based on the band of byte input and output, whole word arithmetic, has reasonably strengthened the mnemon scale, has strengthened the performance of this memory logic aspect anti-linearity and difference analysis.

But, the sequence that above-mentioned sequence perturbation motion method generates, balance is bad, i.e. each element value skewness in element value space in the sequence that generates after disturbance of random sequence.This will make the sequence of output that very big safety defect is arranged.

Summary of the invention

The objective of the invention is to overcome the deficiencies in the prior art, a kind of sequence perturbation motion method and encryption method towards word, band memory is provided.This sequence perturbation motion method is a feature based on whole word operation, with band memory, that is to say to allow the sequence be the unit input with the word, and be unit output again with the word behind the disarrangement device by a band memory.In the stream cipher design,, improve key stream randomicity of sequences and anti-analysis ability by setting up this disarrangement device.

If no special instructions, the word of mentioning among the present invention is the n bit words.

In order to reach the foregoing invention purpose, this method comprises 2 ^mIndividual mnemon, a S box.The input word sequence, the word sequence of output after upsetting is characterized in that comprising:

Steps A presets 2 ^mIndividual mnemon Deposit a n bit words in each mnemon; M, n are natural number;

Step B is to the word sequence of input x=(x ₀, x ₁...) in each word x _i, be done as follows:

A) get x _iThe value h of high m bit;

B) behind known h, with the content y in h the mnemon _hWith input word x _iCarry out xor operation, the word z of output after upsetting _i, promptly

C) upgrade mnemon, get x _iThe value t of low m bit.Behind known t, calculate earlier

Promptly use

Upgrade the value of t mnemon.Calculate again

Promptly with the y that had been updated _tAfter the effect of S box with y _hXOR upgrades the value of h mnemon.Wherein S represents an orthomorphic permutation from the word to the word.S (x _i), S (y _t) respectively with x _i, y _tBe input, calculate the functional value of S, the input and output of this nonlinear function are a n bit words.

Among described steps A, the B, n gets 8 usually, also can be 6,4.

In the described steps A, initially preset described 2 with the initial key of cryptographic algorithm or initial vector or random value or certain group constant ^mThe content of each mnemon in the individual mnemon.

Among the described step a, get x _iThe value h of high m bit, be to x _iDo the operation of the n-m position that moves to right, i.e. h=x _i＞＞(n-m);

Among the described step c, get x _iThe value t of low m bit, be to x _iDo mould 2 ^mOperation, i.e. t=x _iMod 2 ^m

Among the described step c, use x _iValue and y through the conversion of S box _tXOR is used to upgrade the content of t mnemon;

Among the described step c, use value and the y of the content of t the mnemon that has been updated through the conversion of S box _hXOR is used to upgrade the content of h mnemon;

Among the described step c, the content of removing t, h mnemon is updated, and all the other mnemon contents are constant.Behind word of every output, generally to upgrade 2 ^mIn the individual mnemon two, but twice situation also can appear same mnemon upgraded sometimes.

The value of described m is the integer between 1 to n-1;

It is orthomorphic permutation that described S box requires, promptly function S (x) and

It all is displacement.

Another object of the present invention is to provide a kind of encryption method, utilize key stream sequence provided by the invention, clear data stream is word for word encrypted, stream cipher arithmetic structural representation of the present invention as shown in Figure 2.

A kind of encryption method, its step comprises:

1) message sender generates key stream according to encryption key and initial vector, and the method that generates key stream is as follows:

1-1) utilize linear feedback shift register to generate source sequence;

1-2) choose some words, import a nonlinear transformation unit, export a word from source sequence;

1-3) with the random source sequence method of reinforcement of the present invention to step 1-2) word that generates carries out conversion;

1-4) with step 1-3) output and word XOR of shift register generate the key stream word.

Repeat above-mentioned 4 steps, can obtain key stream word sequence.

2) key stream that obtains and origination message step-by-step XOR are realized origination message is encrypted, and encrypting messages are sent to message receiver;

3) message receiver has decruption key identical with encryption key and initial vector, utilizes step 1) to generate the method for key stream, obtains key stream;

4) key stream that obtains and encrypting messages step-by-step XOR are realized the deciphering to encrypting messages, obtain origination message.

Described step 1-2) the nonlinear transformation unit in is selected finite state machine usually for use or is not realized with the nonlinear function of memory.

The scale of mnemon has material impact to algorithm security, and sequence upset method of the present invention has been improved the sequence balance defect of bad after original technology disturbance.When this method is put in order the band memory logic of word arithmetic in design based on whole word input, output, reasonably strengthen the scale of mnemon, strengthened the performance of this memory logic aspect anti-algebraical sum difference analysis, and the sequence of output has had good balance.Compare with single-bit band memory logic, remember logic based on the band of word and not only be easy to strengthen the scale of mnemon, and on application efficiency, can significantly improve.Sequence upset method based on the mixed type band memory logic of putting in order word operation of the present invention comprises transforming function transformation function and S box, and it is exported by word after utilizing transforming function transformation function and S box to upset to each word of importing again.Article one, the relatively more fragile key stream sequence of anti-analysis ability is passed through its upset, and sequence complexity can be enhanced.Why saying that this class band memory logic is a mixed type, is because it has the double grading that the type band memory logic box that adds up stirs type band memory logic concurrently.This scheme can be used for the design of stream cipher algorithm and Hash function easily.

Compared with prior art, the good effect that has of the present invention is:

Sequence perturbation motion method of the present invention has improved the unbalanced problem of sequence after original technology disturbance.Encryption method of the present invention is word for word encrypted clear-text message, has improved the software of encrypting and has realized speed.The key stream sequence has stronger fail safe through upsetting.

Description of drawings

Fig. 1 is n=8, and the m=4 time series is upset schematic diagram;

Fig. 2 is the stream cipher arithmetic structural representation.

Embodiment

When implementing technical scheme of the present invention, at first, select suitable n, m.Generally, n is an even number, and m gets n/2.Secondly, select the good orthomorphic permutation of algebraically, difference, linear behavio(u)r as the S box.The S box can be regarded as system key, also can not maintain secrecy.

Enforcement can be divided into two basic steps:

Steps A is to 2 ^mThe content of individual mnemon

Initialize.Application mode according to concrete can be provided by the basic key or the initial vector of cryptographic algorithm, also can be by presetting with random number or certain group constant.

Step B is to the input word sequence x=(x ₀, x ₁...) in each word x _i, be done as follows:

a)h＝x _i＞＞(n-m)；

B) output $z_i=x_i\⊕y_h$

C) upgrade mnemon, make t=x _iMod 2 ^mOrder successively

Below, in conjunction with the accompanying drawings 1, n is got 8, the m value is that 4 o'clock embodiment is illustrated.Input this moment, output and mnemon are the byte of 8 bits.If list entries x, output sequence z.

The S box is chosen as follows:

??61	??97	??FF	??E9	??66	??56	??F1	??F3	??54	??72	??CC	??4D	??85	??52	??7A	??70
																??D0	??2E	??4C	??58	??BE	??88	??7F	??5A	??2F	??1B	??47	??AF	??9B	??D5	??BF	??81
??C3	??4E	??86	??2D	??6A	??9C	??CE	??20	??2B	??53	??6D	??FD	??3C	??BC	??33	??22
																??F7	??59	??C9	??63	??6E	??8D	??DD	??F2	??E3	??1A	??75	??DA	??13	??1D	??68	??42
??A4	??3F	??B7	??46	??90	??12	??73	??EB	??FA	??F6	??09	??40	??A5	??E0	??B4	??B1
																??51	??8E	??06	??34	??7D	??DF	??99	??6F	??AA	??0B	??80	??95	??25	??EA	??87	??CD
??DC	??0C	??43	??FB	??A7	??BD	??9E	??FC	??EE	??9F	??74	??B6	??CF	??EF	??16	??0F
																??78	??D1	??92	??64	??D6	??84	??48	??41	??08	??60	??5D	??2A	??B8	??4F	??E2	??69
??01	??C1	??31	??5F	??62	??49	??B2	??93	??00	??CB	??04	??18	??07	??71	??17	??E4
																??AC	??8B	??B0	??7E	??F8	??44	??5B	??AD	??98	??A0	??27	??4B	??3A	??B5	??F0	??83

??61	??97	??FF	??E9	??66	??56	??F1	??F3	??54	??72	??CC	??4D	??85	??52	??7A	??70
																??F9	??14	??E7	??23	??77	??D2	??10	??AE	??B3	??36	??30	??3B	??1C	??03	??82	??38
??0E	??7B	??50	??A6	??1F	??7C	??CA	??C2	??02	??2C	??A9	??8A	??39	??15	??F4	??D9
																??A3	??55	??32	??96	??C8	??8C	??C0	??05	??67	??1E	??EC	??19	??29	??89	??F5	??21
??37	??BB	??E1	??57	??A2	??C7	??E6	??8F	??AB	??91	??35	??28	??D3	??D7	??79	??BA
																??A1	??6C	??B9	??DE	??A8	??5E	??FE	??6B	??C5	??ED	??65	??9A	??45	??C6	??C4	??9D
??94	??24	??0D	??0A	??E5	??76	??3D	??E8	??26	??5C	??D4	??4A	??D8	??11	??DB	??3E

Annotate: numeral is 16 systems and represents in the form.

When m=4, have 16 mnemons, establish 16 mnemons and be by random initializtion:

(0xea，0x63，0xe6，0x57，0xa8，0xd6，0x54，0x2e，0x17，0x4f，0x98，0x40，0x2b，0xfd，0xc1，0x9a)。

As x=(0x4a, 0x77 ...).

x ₀=0x4a, h=4, then Shu Chu first byte is

T=10 calculates

Then the 10th mnemon is updated to 0x91, and the 4th mnemon is updated to 0x23.At this moment, 16 mnemons are updated to:

(0xea，0x63，0xe6，0x57，0x23，0xd6，0x54，0x2e，0x17，0x4f，0x91，0x40，0x2b，0xfd，0xc1，0x9a)。

After byte of every output, generally to upgrade two in 16 mnemons, but also can occur same mnemon upgraded twice situation sometimes.Primary renewal meeting this moment is upgraded for the second time to cover.

For example, x ₁=0x77, then h=t=7.Second byte of output is

Calculate

Then the 7th mnemon is updated to 0x60, and at this moment, 16 mnemons are updated to:

(0xea，0x63，0xe6，0x57，0x23，0xd6，0x54，0x60，0x17，0x4f，0x91，0x40，0x2b，0xfd，0xc1，0x9a)。

Claims (10)

1. the sequence perturbation motion method towards word, band memory the steps include:

1) presets 2 ^mIndividual mnemon

To the content initialize of each mnemon, store a n bit words; M, n are natural number;

2) for each the word x in the key stream sequence of input _iCarry out following steps successively:

A) get current word x _iThe value h of high m bit; Wherein each word is the n bit words;

B) utilize the content y of h mnemon _hWith input word x _iCarry out xor operation, the word z of output after upsetting _i

C) get current word x _iThe value t of low m bit;

D) with current word x _iThrough the value of S box conversion and the content y of t mnemon _tCarry out XOR, and upgrade y with its output result _t

E) y that step d) was upgraded _tValue and described y through the conversion of S box _hXOR, and export the result with it and upgrade y _h

The word z that 3) will export successively _iAs the key stream sequence after upsetting.

2. the method for claim 1 is characterized in that according to the initial key of cryptographic algorithm or the initial vector content initialize to each mnemon.

3. the method for claim 1 is characterized in that utilizing the content initialize of random number to each mnemon.

4. the method for claim 1 is characterized in that the value of described m is: the integer between 1 to n-1.

5. method as claimed in claim 4 is characterized in that in the described step a), gets current word x _iThe method of value h of high m bit be: to x _iDo the operation of the n-m position that moves to right.

6. method as claimed in claim 4 is characterized in that in the described step c), gets current word x _iThe method of value t of low m bit be: to x _iDo mould 2 ^mComputing.

7. the method for claim 1 is characterized in that described S box is an orthomorphic permutation.

8. an encryption method the steps include:

1) message sender generates key stream according to initial key and initial vector;

2) message sender is realized the key stream and the origination message step-by-step XOR that obtain origination message is encrypted, and encrypting messages is sent to message receiver;

3) message receiver utilizes initial key and initial vector, generates key stream;

4) message receiver is realized the deciphering to encrypting messages with key stream that generates and the encrypting messages step-by-step XOR that receives, and obtains origination message;

Wherein, the method for described generation key stream is: preset 2 ^mIndividual mnemon

To the content initialize of each mnemon, store a n bit words, m, n are natural number; Utilize linear feedback shift register to generate source sequence, and from the source sequence of each generation, choose nonlinear transformation unit of some word inputs, export a word x _iThen to the word x of each output _iCarry out following steps successively: a) get current word x _iThe value h of high m bit; B) utilize the content y of h mnemon _hWith input x _iCarry out xor operation, the word z of output after upsetting _iC) get current word x _iThe value t of low m bit; D) with current word x _iThrough the value of S box conversion and the content y of t mnemon _tCarry out XOR, and upgrade y with its output result _tE) y that step d) was upgraded _tValue and described y through the conversion of S box _hXOR, and export the result with it and upgrade y _hF) with the z that exports _iGenerate the key stream word with a word XOR of shift register; At last, the key stream word according to output successively obtains the key stream sequence.

9. method as claimed in claim 8 is characterized in that described nonlinear transformation unit is a finite state machine or not with the nonlinear function of memory.

10. method as claimed in claim 8 is characterized in that described S box is an orthomorphic permutation; The value of described m is: the integer between 1 to n-1.

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