JP2010528511A - Software encryption method, software decryption method, software encryption device, and software decryption device - Google Patents

Abstract

  The present invention relates to the field of computer security, and more particularly to a software encryption method, a software decryption method, a software encryption device, and a software decryption device. The decryption process of the present invention includes the following steps: Step 201, randomly selecting t factors of the threshold secret key from n paragraphs of the second software ciphertext; Restore the first software ciphertext and the private key ciphertext PSK from the software ciphertext, where n is a positive integer greater than 1 and t is less than or equal to n: Step 202: Extract the private key ciphertext PSK Generating a second secret key according to the t factors of the threshold secret key, and decrypting the secret key ciphertext PSK into the first secret key SK using the second secret key; 203. Decrypt the first software ciphertext using the first secret key SK. An advantage of the present invention is that it improves the protection of software encryption keys and makes it difficult for crackers to crack the software by tracking the software loading process.

Description

TECHNICAL FIELD The present invention relates to the field of computer security, particularly to the field of computer encryption, and more particularly to a software encryption method, a software decryption method, a software encryption device, and a software decryption device.

BACKGROUND ART In recent years, software has become a necessity with independent values and functions, execution processes, coding, and the like. In some software, objects tend to be stolen by competitors and other organizations or individuals. Therefore, software, especially software programmed in an intermediate language (Java, NET, etc.) can be very easily decoded by retrograde analysis. This is performed using, for example, NET Reflect (a retrograde analysis tool from Microsoft) or JAD (a retrograde analysis tool from Java). This gives information about the core algorithm, encoding, etc., and when such information is used maliciously by a cracker, for example when imitating the core algorithm of a software and approaching registered software, This is a loss for developers.

  In the prior art, measures to confuse crackers in cracking behavior by renaming internal functions, rearranging control flows or other methods have some effect and were de-encoded by this measure Software programs have been read, made difficult to understand, or read, making them impossible to understand. However, this kind of protection mechanism for the source code cannot avoid the software program being de-encoded, so the possibility of losing the software program information still remains.

  The article "Using DES Encryption Algorithm to Protect Java Source Code" (published in Computer and Information technology in May 2005) discloses a solution for encrypting software compiled by Java and decrypting it during operation. . This solution uses the Data Encryption Standard (DES) to encrypt the Java execution program, stores the encrypted encoding program and private key in the memory, and uses the loader to encrypt the encrypted Java encoding program. And the key is loaded into the system, the secret key is extracted, the encoding program is decrypted, it is converted into an executable encoding form, and this is loaded into the Java virtual machine and activated.

  The method described above is very easily traceable by the cracker, and from the start of the program, the cracker can track each step with just a debug tool. If the program accesses a particular file every time it runs and gets the private key or system symbol name from this file, this allows the cracker to compare the file in the comparison table for the private key or system symbol name for the program. If one guesses and the cracker confirms that this file is a private key file, the cracker will try every possible means of cracking the file; and once the file is cracked, the ciphertext in the software coding Converted to plain text in software coding, the source code for this software is generated by retrograde analysis, which causes losses to the software owner.

In order to solve the above-described problems and increase the difficulty of software decompilation, the object of the present invention is to provide the following software encryption method and corresponding decryption method. Here, a threshold encryption feature is included, and each time the software is started, the obtained threshold secret key factor address is different. This makes it impossible for the cracker to specify the secret key address.

  The present invention also provides a software encryption device and a corresponding decryption device. The device can store multiple factors of the threshold secret key in different paragraphs of the software, and at decryption, these factors of the threshold secret key can be randomly extracted from several paragraphs of the software. Can be obtained for decryption.

Step 101: The software plaintext in the storage medium is encrypted into the first software ciphertext using the first encryption module. Here, the secret key for decryption is the first secret key SK;
Step 102: The second encryption module creates a second secret key using n factors of the threshold secret key, and uses the second secret key to generate the first secret key SK. The private key ciphertext PSK is encrypted, and this private key ciphertext PSK is spliced to the first software ciphertext. Where n is a positive integer greater than 1;
Step 103: Dividing the secret key ciphertext PSK and the first software ciphertext into n paragraphs as a whole by using an encapsulation module, and converting the threshold secret key factor into the paragraphs Splicing is performed to form a second software ciphertext, and the second software ciphertext is stored in the storage medium.

  In another aspect of the encryption method of the present invention, the encryption method identified in step 101 includes a symmetric encryption algorithm or an asymmetric encryption algorithm.

  In yet another aspect of the encryption method of the present invention, the threshold secret key algorithm used in step 102 comprises a Shamir threshold secret key scheme.

ここで×は算術的な乗算演算であり、同時にしきい値秘密鍵ファクタｋのハッシュ値ｈが計算され、Ｃ’_０〜Ｃ’_ｍの値が結合されてＣ’が形成され、ｎ個のパラグラフの複数のこのＣ’およびその相応するハッシュ値ｈがスプライス接続されて、前記第２のソフトウェア暗号文が形成される。 In yet another aspect of the encryption method of the present invention, in the step 103, the encapsulation module divides the secret key ciphertext PSK and the first software ciphertext into n paragraphs as a whole as a statistical data. C represents any paragraph in the n paragraphs, paragraph C includes blocks C ₀ , C ₂ ,..., C _m−1 , and the following equation is performed in each paragraph C, which Corresponding to k:

Here, x is an arithmetic multiplication operation. At the same time, a hash value h of the threshold secret key factor k is calculated, and the values of C ′ _{0 to} C ′ _m are combined to form C ′. A plurality of this C ′ in the paragraph and its corresponding hash value h are spliced together to form the second software ciphertext.

The method for software decryption includes the following steps during the process of loading the software:
Step 201: The t-factor of the threshold secret key is selected at random from the n paragraphs of the second software ciphertext by the decapsulation module; from the second software ciphertext to the first software cipher Reconstructs the text and private key ciphertext PSK, where t is greater than or equal to 1 and less than or equal to n and n is a positive integer greater than 1;
Step 202: Extract the secret key ciphertext PSK, create a second secret key by a second decryption module according to the t factors of the threshold secret key, and use the second secret key Decrypting the secret key ciphertext PSK into a first secret key SK;
Step 203: The first decryption module decrypts the first software ciphertext using the first secret key SK, sends the software plaintext to the CPU, and executes the software.

In another aspect of the cryptanalysis method of the present invention, in step 201, the decapsulation module performs calculations in each of n paragraphs of the second software ciphertext: C ₀ , C ₁ ,. Remove C _m-1 to obtain the following equation:
^{_{0 = -C 'm k m +}} C' m-1 × k m-1 -C 'm-2 × k m-2 + ··· + (- 1) m-1 × C' 0 (P0)
If the hash value of k corresponds to the corresponding hash value h of paragraph C ′, k in this equation is solved and the values of C _{0 to} C _m−1 are changed from C ′ _{0 to} C ′ _m−1 to k And C ₀ -C _m-1 are combined to give paragraph C. This paragraph is one of the integrated n paragraphs of the first software ciphertext and the second secret key ciphertext; n k are solved, and the first software ciphertext and The second secret key ciphertext PSK is restored from the second software ciphertext.

  In yet another aspect of the decryption method of the present invention, a polynomial Newton iteration method is used to solve k in this equation (P0).

  The software encryption device has the following features. That is, the apparatus includes a first encryption module, a second encryption module, and an encapsulation module; using the first secret key SK, the first encryption module converts the software plaintext to the first software encryption. A second encryption module connected to the first encryption module uses the n factors of the threshold secret key to form a second encryption module; A first secret key SK is encrypted into a secret key ciphertext PSK using a secret key, and the secret key ciphertext PSK is stored in the first software ciphertext; connected to the second encryption module; The encapsulation module divides the first software ciphertext into n paragraphs, splices the factor of the threshold secret key into the paragraphs; To form a software cipher text.

  An apparatus for software decryption has the following characteristics. That is, the apparatus includes a decapsulation module, a second decryption module, and a first decryption module; wherein the decapsulation module stores a second software ciphertext in a first Decapsulates the software ciphertext and the private key ciphertext PSK, and randomly selects t factors of the threshold secret key from n paragraphs of the second software ciphertext; The second decryption module connected to the module forms a second secret key according to the t factors of the threshold secret key and uses this second secret key to secret key ciphertext PSK. Is decrypted into a first secret key SK, and the first decryption module coupled to the second decryption module includes the first soft key Cipher decrypts the wear ciphertext by using the first secret key SK, to give a software plaintext, which feed on the CPU, the software is executed.

  The effect of the present invention is that the protection of the software encryption key is enhanced, making it more difficult for crackers to crack the software. This crack is done by tracking the software loading process and obtaining the physical address of the private key by tracking the software loading process. Here the purpose of cracking the software is achieved by analyzing the secret key. Furthermore, the present invention improves the current solution for encrypting software and improves its security by the technique of dynamically storing private keys.

Flowchart for implementing software encryption in accordance with the present invention Flowchart for performing software decryption in accordance with the present invention Structural scheme of an apparatus for performing software encryption according to the present invention Structural scheme of an apparatus for performing software decryption according to the present invention Structural diagram of an apparatus for carrying out the present invention

Detailed Description of the Preferred Embodiments The present invention is described in detail below in conjunction with the drawings.

  The present invention uses threshold secret key theory to provide further protection for the first secret key, splicing the threshold secret key factor into the encrypted software, thereby tracking the program run Each time you do it, the cracker gets a different jump address. As a result, the cracker cannot specify a location to search for the first secret key. The software protected by the present invention is not limited to an executable program, but includes a functional module and a software core algorithm. The current threshold encryption method uses a random number as a second secret key, encrypts the first secret key SK into a secret key ciphertext PSK, and at the same time calculates a threshold secret for calculating this random number. Create n factors of the key; when it is necessary to decrypt the secret key, t factors of the threshold secret key (t ≦ t) in order to create the second secret key for decryption n) is only required. The purpose of proposing threshold cryptography is to scatter rights and increase security; rights scatter occurs when using threshold cryptography to perform decryption and Is kept only one secret key factor, this decryption is only done if the number of participants has reached a certain number (threshold t); This is a case where encryption becomes meaningless by obtaining one key factor. As a result, it is still impossible to perform decryption unless the number of cracked persons in this group reaches a threshold; on the other hand, loss of key factors that adversely affect normal decryption The case is prevented. This is because cryptanalysis is still feasible as long as the number of people with valid key factors is above a threshold. In this embodiment of the invention, the threshold encryption algorithm uses the Shamir scheme as an example. However, this is not limited to the Shamir scheme, and an Asmuth-Bloom threshold secret key scheme can also be used.

Before selling a piece of software, software vendors encrypt the software plaintext using cryptographic algorithms. This cryptographic algorithm is a currently available symmetric or asymmetric cryptographic algorithm such as AES, DES or RSA, ECC. If a symmetric encryption algorithm is used, the software encryption private key is the same as the decryption private key. This is also used for decryption and the decryption private key is the private key SK (ie the first private key). When an asymmetric encryption algorithm is used, the encryption secret key has a corresponding relationship with the decryption secret key of the asymmetric encryption algorithm, and the decryption secret key is the secret key SK in the present invention (ie, , First secret key). Since the software private key SK determines whether the software is cracked or not, the security of the private key SK is very important, and the present invention particularly uses the Shamir scheme of threshold encryption. to, threshold secret key K _1, K _{2, ···,} the second to create a secret key by calculating the n-number of factors K _n, the second private key, secret key SK Is encrypted into the private key ciphertext PSK, and the private key ciphertext PSK is spliced into the encrypted software, eg, it is spliced into the head or tail of the encrypted software . Furthermore, the n factors of the threshold secret key are spliced into different physical paragraphs of the encrypted software by a strong splice algorithm (or simple splicing mode). For example, it is spliced to the software head or tail. In the present invention, this is performed by: Step 1, encrypting the software that needs protection; Step 2, encrypting the first secret key SK from Step 1; Step 3, Step 2 Splice the secret key factors to perform encryption; and if the software needs to be decrypted for operation, t threshold threshold keys (1 ≦ t ≦ n, where (T and n are both positive integers) are randomly obtained from the protected software ciphertext, and then the first secret key SK of the encrypted software uses the Shamir scheme Thus, the private key ciphertext PSK is decrypted and the software ciphertext is decrypted. This method of restoring the threshold secret key gives dynamic characteristics to the software loading process, each time the threshold secret key for decryption is obtained from different positions in the software. This therefore effectively increases the difficulty of cracking by cracking the method of tracking the software loading process.

  A flowchart of the software encryption process of the present invention is shown in FIG.

  Step 101, select a suitable symmetric encryption algorithm such as AES, DES, etc. and encrypt the software plaintext into a first software ciphertext by using the first encryption module, where the secret key used is The first secret key SK.

Step 102, the second encryption module protects the above-mentioned secret key SK by using the Shamir algorithm in the threshold encryption algorithm, and uses the Shamir scheme of the language complement polynomial algorithm in the Z _p domain, t Generate a -1 order polynomial, where Z _p is the main region:
p _n (x) = a ₀ + a ₁ X + a ₂ X ² +... + a _t−1 X ^t−1
_Here, coefficient _a 0 in _{P n (x), ··· a} n is randomly created.

When X ₁ = 1, calculate p _n (1) = a ₀ + a ₁ + a ₂ +... + A _t−1 ,
When X _n = n, p _n (n) = a ₀ + a ₁ n + a ₂ n ² +... + A _t−1 n ^t−1 is calculated.

Here, p _n (1),... P _n (n) <2 ⁶⁴ , n is a positive integer greater than 1, t is a positive integer greater than or equal to 1, and smaller than n .

Thereafter, n factor pairs K ₁ = (1, P _n (1)),... K _n = (n, P _n (n)) of the threshold secret key are created, and a _{0 is set} to the second The private key SK is encrypted into the private key ciphertext PSK. Alternatively, after encryption, the private key ciphertext PSK is spliced to the head or tail of the first software ciphertext, and a prior art storage method can be used in this step.

  Step 103, dividing the integrated whole of the first software ciphertext and the key ciphertext into n paragraphs using a decapsulation module, and then n factors of this threshold secret key n Splice to the paragraph. Here, each of the n factors of the secret key is directly spliced to the head and tail of each paragraph of the first software ciphertext to form a second software ciphertext. This is stored in a storage medium. As shown, the black part is the secret key factor and the white part is n paragraphs; it is also possible to use the subsequent splice concatenation method to form a more complex second software ciphertext. Is possible.

ここで×は算術的な乗算演算である。有利な実施形態として、各パラグラフＣ_ｉの長さはｋの長さに等しい。すなわち、ｌｅｎｇｔｈ（Ｃ_ｉ）＝ｌｅｎｇｔｈ（ｋ）である。例えば、このソフトウェアは暗号化された後にｎ個のパラグラフに分けられる。ここでは特定のパラグラフＣは１２８バイトの長さを有している。また秘密鍵のファクタは１６バイトの長さを有している。その後Ｃは８個のパラグラフに分けられる。すなわちｍ＝７である。Ｃにおける各パラグラフＣ_ｉの長さは、１６バイトの長さを有する。同時にｈ＝ｈａｓｈ（ｋ）が計算される。すなわち、しきい値秘密鍵ファクタｋのハッシュ値が記録される。これは、復元されたしきい値ファクタが、暗号解読時に正しいか否かを検証するために用いられる。完全なＣ’を形成するためにＣ’_０〜Ｃ’_ｍを結合した後、これはハッシュ値ｈ（ｈはパラグラフＣ’の前または後に加えられる）とともにスプライス結合され、その後、格納のための最終的なソフトウェア暗号文、すなわち第２のソフトウェア暗号文が、全てのパラグラフＣ’および相応するハッシュ値ｈをスプライス結合することによって形成され、この第２のソフトウェア暗号文が記憶媒体内に格納される。 C represents a particular paragraph of the first software ciphertext, where each paragraph C includes C ₀ , C ₂ ,..., C _m−1 , and k is the threshold secret key factor pair K _i. Where P _n (i) is a specific splicing process:

Here, x is an arithmetic multiplication operation. As an advantageous embodiment, the length of each paragraph C _i is equal to the length of k. That is, length (C _i ) = length (k). For example, the software is encrypted and divided into n paragraphs. Here a particular paragraph C has a length of 128 bytes. The secret key factor has a length of 16 bytes. C is then divided into 8 paragraphs. That is, m = 7. The length of each paragraph C _i in C has a length of 16 bytes. At the same time, h = hash (k) is calculated. That is, the hash value of the threshold secret key factor k is recorded. This is used to verify whether the restored threshold factor is correct at the time of decryption. After combining C ′ _{0 to} C ′ _m to form complete C ′, this is spliced together with a hash value h (h is added before or after paragraph C ′) and then for storage The final software ciphertext, ie the second software ciphertext, is formed by splicing all the paragraphs C ′ and the corresponding hash value h, and this second software ciphertext is stored in the storage medium. The

Within the Shamir threshold encryption scheme, the t factors of the secret key are used to recover the second secret key a ₀ and the PSK is decrypted. Thus, each time the encrypted software is loaded, the software loader randomly chooses n factors t of the private key to decrypt the PSK. Thus, an advanced and powerful protection mechanism with dynamic characteristics is provided, preventing crackers from tracking and analyzing the software loading process.

FIG. 2 is a flowchart of software loading and decryption according to the present invention. At the stage of starting the software, the second software ciphertext is loaded from the storage medium into the memory by the loader. Further, in this figure, the black part is the secret key factor and the white part is the first software ciphertext and PSK; the splicing method illustrated in step 103 is not used in the encryption step, and the secret key factor If only n factors are spliced directly to the corresponding paragraph head or tail of the software ciphertext, t factors of the secret key are randomly generated by the decapsulation module in step 201. , Obtained by directly selecting t paragraphs from the ciphertext. If the splicing method shown in step 103 is used during encryption, one cipher text paragraph C ′ and its corresponding hash value h are selected by the decapsulation module, and the threshold private key The factor k is brought in so that the ciphertext paragraph is restored. The restoration algorithm is shown below:
C _{0 to} C _m−1 are removed from E ₀ to Em, C _m−1 = C ′ _m is substituted into (Em−1), and the formula C _m−2 = C ′ _m−1 −C ′ _m × k + C _m × K ² is obtained. This is substituted by (Em-2),..., (E0); finally the following polynomial is formed.
^{_{0 = -C 'm k m +}} C' m-1 × k m-1 -C 'm-2 × k m-2 + ··· + (- 1) m-1 × C' 0, which as P0 The secret key factor k is the root of the polynomial described above, which is found by computing the polynomial in the numerical domain, and k is the second software ciphertext C ′ ₀ , C ′ ₁ ,. _-Restored from C'm. A Newton iterative algorithm is used in this example to look for one or more roots of the polynomial P0.

を計算する。ここでｉ＝０〜ｍであり、ｆ’（ｋ）はｆ（ｋ）の導関数であり、すなわち、
ｆ’（ｋ）＝−Ｃ’_ｍ×ｍ×ｋ^ｍ−１＋Ｃ’_ｍ−１×（ｍ−１）×ｋ^ｍ−２−Ｃ’_ｍ−２×（ｍ−２）×ｋ^ｍ−３＋・・・＋（−１）^ｍ−２×Ｃ’_１
（ｃ）｜ｋ_ｉ−１−ｋ_ｉ｜＜１になるまでステップｂを繰り返す、その後ｋ_ｉ＋１はＰ１の根に近似する。 _{(A) y = -C 'm} k m + C' m-1 × k m-1 -C 'm-2 × k m-2 + ··· + (- 1) m-1 × C' 0 = f (K) (P1), where the initial value k ₀ is arbitrarily selected, for example, k ₀ = 2 ^{length (k) −1} .
(B)

Calculate Where i = 0 to m and f ′ (k) is the derivative of f (k), ie
f ′ (k) = − C ′ _m × m × k ^m−1 + C ′ _m−1 × (m−1) × k ^m−2 −C ′ _m−2 × (m−2) × k ^m−3 + ... + (-1) ^m-2 × C ′ ₁
(C) Repeat step b until | k _i-1 −k _i | <1, then k _{i + 1} approximates the root of P1.

(D) hash (k _{i + 1} ) = h, or hash (k _{i + 1} +1) = h, hash (k _{i + 1} −1) = h, where h is the h value in the encryption step (4), The k _{i + 1} computed in this step is the threshold secret key factor k in the encryption step and jumps to step (f); if this is not equal, there is no algorithm to find the root of the number, Step (e) is entered. The hash algorithm is a one-way algorithm in the present invention, that is, the original data is not derived in reverse after the data is calculated, so it is necessary to compare whether the data is old before and after transmission. In this case, it is only necessary to compare hash values before and after transmission.

  (E) If k is not found in step (d), this means that P0 has multiple roots, and other actual roots are obtained by the following method.

The root k _{i + 1} obtained in step (d) is used as the new k ₀ .
If b ₀ = −C ′ _m , b _k = (− 1) ^k−1 × C ′ _m−k + k ₀ × b _k−1 (where k = 1, 2,..., m−1) A new polynomial f (k) = b ₀ × k ^m−1 + b ₁ × k ^m−2 +... + B _n−1 (P2) occurs;
Using the steps b to c described above, the actual root of the new equation P2 is calculated, thus obtaining another actual route for P0.

  This step (e) calculates all the actual roots of P0 and checks step (d) each time step (e) is performed to determine whether an actual secret key factor has been obtained; The factor k of the threshold secret key is obtained.

After obtaining a factor k of the secret key in (f) cipher text paragraph, returns by substituting E0 to Em, the first software cipher text _{C 1, C 2, ···,} a _{C m,} the second of software encryption Restored from sentences C ′ ₀ , C ′ ₁ ,..., C ′ _m .

  Steps a to f are performed on n paragraphs C ′ to obtain all factors k of the threshold secret key necessary for decrypting the secret key ciphertext PSK, and all ciphertext C ′ using k. To form a first software ciphertext.

ここでｙ_ｋ＝Ｐ_ｎ（ｘ_ｋ）であり、ｘ_ｉおよびｘ_ｎは復元されたしきい値秘密鍵ファクタペアにおいてｘ_ｉであり、ここでｉ≠ｋであり、最終的にｘ＝０とすると、Ｐ_ｎ（０）＝ａ_０が得られる。 Step 202 restores t factors of the threshold secret key,
K _i = (x _i , p _n (x _i )), 1 ≦ i ≦ t, the second decryption module uses t k to form a new polynomial.

Here is _{y k = P n (x k} ), x i and _{x n} are _{x i} in the restored threshold secret key factor pair, where a i ≠ k, finally x = 0 Then, P _n (0) = a ₀ is obtained.

Extract the PSK in the first software ciphertext, use a ₀ as the secret key for decrypting the secret key ciphertext PSK, and the first secret key SK to decrypt the encrypted software Get.

  Step 203, SK is used to decrypt the encrypted software by the first encryption module. This provides the original software plaintext.

  The CPU operates according to this software plaintext.

  A schematic diagram of the encryption device of the present invention is shown in FIG. The apparatus includes a first encryption module, a second encryption module, and an encapsulation module; the first encryption module converts a software plaintext to a first software ciphertext using a first secret key SK. Encryption; the second encryption module connected to the first encryption module forms a second encryption module using n factors of a threshold secret key, and the first encryption module The private key SK is encrypted in the private key ciphertext PSK using the second private key, and the private key ciphertext PSK is stored in the first software ciphertext; connected to the second encryption module The encapsulated module divides the first software ciphertext into n paragraphs, splices the factor of the threshold secret key into the paragraphs; To form a software cipher text.

  A schematic diagram of the decryption apparatus of the present invention is shown in FIG. The apparatus includes a decapsulation module, a second decryption module, and a first decryption module; the decapsulation module decapsulates a second software ciphertext into a first software ciphertext, and randomly Select t factors of the threshold secret key from n paragraphs of the second software ciphertext; the second decryption module connected to the decapsulation module Forming a second secret key according to the t factors and decrypting the secret key ciphertext PSK into the first secret key SK using the second secret key; connected to the second decryption module Wherein the first decryption module decrypts the first software ciphertext using the first secret key SK, That.

  A schematic operational diagram of the device of the present invention is shown in FIG. This also includes a loader for loading software from the storage medium and the encryption device shown in FIG. Here, the redundant description of the same part is not repeated. The loader loads the second software ciphertext from a storage medium (for example, a hard disk) and inputs it to the decryption device. The decryption device converts the second software ciphertext into software plaintext and transmits it to the CPU for execution.

  The effects of the present invention are as follows. That is, encrypting executable software, making it difficult for crackers to obtain a secret key by simply tracking the software loading process, and preventing the software from being decrypted and compiled by methods such as retrograde analysis That's it. This improves the protection of the encryption key of the software and allows the cracker to achieve the goal of cracking the software by obtaining the physical address of the private key by tracking the software loading process and analyzing this private key. In addition, the present invention improves upon the currently used solution of encrypting software to increase its security by a technique for dynamically storing private keys.

  The specific embodiments described above are merely used to describe the present invention, and the present invention is not limited thereto.

Claims (9)

A method for encrypting software, the method comprising the following steps:
Step 101: encrypting the software plaintext in the storage medium into a first software ciphertext using a first encryption module, wherein the secret key for decryption is the first secret key SK;
Step 102: The second encryption module creates a second secret key using n factors of the threshold secret key, where n is a positive integer greater than 1,
Encrypting the first secret key SK into a secret key ciphertext PSK using the second secret key, and splicing the secret key ciphertext PSK to the first software ciphertext;
Step 103: Using an encapsulation module, the secret key ciphertext PSK and the first software ciphertext are divided into n paragraphs as a whole, and the factor of the threshold secret key is Splicing the paragraph to form a second software ciphertext, and storing the second software ciphertext in the storage medium;
A method for encrypting software, characterized in that:   The software encryption method according to claim 1, wherein the encryption method specified in step 101 includes a symmetric encryption algorithm or an asymmetric encryption algorithm.   The software encryption method of claim 1, wherein the threshold secret key algorithm used in step includes a Shamir threshold secret key scheme or an Asmuth-Bloom threshold secret key scheme. In step 103, the encapsulation module divides the secret key ciphertext PSK and the first software ciphertext as a whole into n paragraphs; C is any of the n paragraphs; Represents a paragraph, and paragraph C includes blocks C ₀ , C ₂ ,..., C _m−1 , the length of each paragraph is the same as the length of the threshold secret key factor k. This is done in paragraph C, which corresponds to k:

Here, x is an arithmetic multiplication operation. At the same time, the hash value h of the threshold secret key factor k is calculated, the values of C ′ _{0 to} C ′ _m are combined, C ′ is formed, and n 4. The software encryption method of claim 3, wherein a plurality of C ′ and the corresponding hash value h of said paragraph are spliced together to form said second software ciphertext. A method for software decryption comprising the following steps during the process of loading software:
Step 201: The decapsulation module randomly selects t factors of the threshold secret key from n paragraphs of the second software ciphertext, where t is greater than or equal to 1 and less than or equal to n , N is a positive integer greater than 1; restore the first software ciphertext and the private key ciphertext PSK from the second software ciphertext;
Step 202: Extract the secret key ciphertext PSK, create a second secret key by a second decryption module according to the t factors of the threshold secret key, and use the second secret key Deciphering the secret key ciphertext PSK into the first secret key SK;
Step 203: The first decryption module decrypts the first software ciphertext using the first secret key SK, sends the software plaintext to the CPU, and executes the software.
A software decryption method characterized by the above. In step 201, the decapsulation module performs a calculation on each of n paragraphs of the second software ciphertext: C ₀ , C ₁ ,..., C _m−1 are removed according to E0 to Em. And get the following equation:
^{_{0 = -C 'm k m +}} C' m-1 × k m-1 -C 'm-2 × k m-2 + ··· + (- 1) m-1 × C' 0 (P0)
If the hash value of k is equal to the corresponding hash value h of paragraph C ′, k in this equation is solved and the values of C _{0 to} C _m−1 are derived from C ′ _{0 to} C ′ _m−1 , k And C _{0 to} C _m-1 are combined to obtain paragraph C, which is a total of n paragraphs of the total of the first software ciphertext and the secret key ciphertext. 6. The software decryption method according to claim 5, wherein n k are solved, and the first software ciphertext and the private key ciphertext PSK are restored from the second software ciphertext.   The software decryption method of claim 6, wherein the polynomial Newton iteration method is used to solve k in the equation (P0). A software encryption device,
The apparatus includes a first encryption module, a second encryption module, and an encapsulation module;
The first encryption module encrypts software plaintext into a first software ciphertext using a first secret key SK;
The second encryption module connected to the first encryption module forms a second encryption module using n factors of a threshold secret key, and the first secret key Encrypting SK into a secret key ciphertext PSK using the second secret key, and storing the secret key ciphertext PSK in the first software ciphertext;
The encapsulation module connected to the second encryption module divides the first software ciphertext into n paragraphs and splices the factor of the threshold secret key to the paragraphs. And forming a second software ciphertext,
A software encryption device. A software decryption device,
The apparatus includes a decapsulation module, a second decryption module, and a first decryption module;
The decapsulation module decapsulates the second software ciphertext into the first software ciphertext and the secret key ciphertext PSK, and randomly generates a threshold secret from n paragraphs of the second software ciphertext. Select t factors of the key;
The second decryption module connected to the decapsulation module creates a second secret key according to the t factors of the threshold secret key, and uses the second secret key to create a secret Decrypting the key ciphertext PSK into the first secret key SK;
The first decryption module connected to the second decryption module decrypts the first software ciphertext using the first secret key SK, obtains a software plaintext, and Software plaintext is sent to the CPU and the software is executed.
A software decryption device characterized by that.

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