CN110418029A - Text Secret Information Hiding and Extracting Method Based on Unicode Encoding - Google Patents

Abstract

The invention discloses a method for hiding and extracting text secret information based on Unicode encoding. The method is: first, the sender replaces each character of the secret information with a binary string using Gödel function encoding, obtains the sender's symmetric key, combines it in front of the binary string of the secret information, and pairs the secret information based on the sender's symmetric key. The binary string is hashed and encrypted, and the hash-encrypted binary string of secret information is replaced by Unicode zero-width control characters with the set rules to form an invisible string and embedded in front of the cover text; then the receiver detects the carrier For the zero-width string in the text, restore the binary string according to the set rules, obtain the receiver's key, and hash and decode the binary string based on the receiver's key; finally authenticate and decode the Gödel function, and output the secret information . The invention improves the transmission security and privacy protection capability of text secret information.

Description

Text Secret Information Hiding and Extracting Method Based on Unicode Encoding

technical field

The invention belongs to the technical field of information hiding, in particular to a method for hiding and extracting text secret information based on Unicode encoding.

Background technique

Information hiding technology is a technology that embeds secret information in original data, such as sensitive information that needs to be hidden. Information hiding techniques can not only be detected and extracted, but also prevent network and text attacks. Information hiding techniques include the embedding and extraction of hidden information. In the embedding stage, it is first necessary to generate a string containing the information that needs to be hidden (such as the author's name, publisher or sensitive information), and then generate the invisible string according to the corresponding algorithm and embed it in a special position in the cover text, For example, document 1 (M.Pal.A survey on digital watermarking and its application[J].International Journal of Advanced Computer Science and Applications, 2016,7(1):153–156.). Text embedded with secret information is transmitted and shared in the Internet. When the secret information of the text needs to be obtained, the secret information can be detected and extracted. After the sensitive information is embedded and before extraction, the hidden secret information should be able to resist various attacks.

Aiming at the problems of text hiding and camouflage, some text watermarking techniques related to Unicode encoding have been proposed by researchers. For example, document 2 (L.Y.Por, K.Wong, K.O.Chee, "A text-based data hiding method using Unicode space characters", The Journal of Systems and Software, 2012, Vol.85, No.5, pp.1075-1082. Doi:10.1016/j.jss.2011.12.023.) proposed a data hiding method called UniSpaCh in 2012, which uses a special space encoded by Unicode to hide secret information in Word. This method utilizes a combination of specific positions and double spaces to hide secret information. The advantage is that the combination of spaces is fully utilized, so it provides higher embedding capacity. But this approach produces some special whitespace in the cover text and is vulnerable to tampering and reformatting types of attacks.

The current text hiding technology has three shortcomings: first, the embedding capacity of text secret information is not high; second, the robustness of secret information against attacks is low; third, secret information may affect the structure and even content of the text, and some The technology does not have good transparency and may create problems that are noticed by attackers.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for hiding and extracting text secret information based on Unicode encoding that can ensure the transmission of secret information in social media, thereby bringing end-to-end security guarantees for SMS and social media users.

The technical solution for realizing the object of the present invention is: a method for hiding and extracting text secret information based on Unicode encoding, comprising the following steps:

Step 1. The sender replaces each character of the secret message with a binary string using the Gödel function encoding;

Step 2. Obtain the sender's symmetric key and combine it in front of the secret information binary string;

Step 3, hashing and encrypting the binary string of the secret information based on the sender's symmetric key;

Step 4. Replace the hash-encrypted binary string of secret information with Unicode zero-width control characters with the set rules to form an invisible string and embed it in front of the cover text;

Step 5. The receiver detects the zero-width character string in the carrier text, and restores the binary character string according to the set rule;

Step 6. Obtain the recipient's key;

Step 7, hash decoding the binary string based on the receiver key;

Step 8: Authenticate and decode the Gödel function, and output the secret information.

Further, the sender described in step 1 replaces each character of the secret information with a binary string using Gödel function encoding, as follows:

Step 1.1. Set η to be any given number, then there is a unique solution <α, β>, let η be the ASCII code of the letter, then <α, β> is the unique number pair of each character of SM:

< ^α ,β>=2α(2β+1)-1 (1)

and 2 ^α (2β+1)≠0

in, is a natural number, exists Make 2 ^α ×k=η+1;

In equation (2), is an odd number;

The embedding algorithm uses equations (2) and (3) to compute <α,β> pairs for each character of the secret message;

Step 1.2. Convert α and β into 6-bit binary strings respectively, and connect them together to generate a 12-bit binary string for each letter;

Step 1.3, splicing the binary strings of each letter together to form a binary string of secret information.

Further, obtaining the sender's symmetric key described in step 2 is combined in front of the secret information binary string, as follows:

Step 2.1. The hash function uses the sending time, that is, the time when the hidden information is generated, as the sender's key, and omits the fourth bit of the time;

Step 2.2. Create a number and convert the number into an 8-bit binary string, that is, the sender's key, which is combined in front of the secret message binary string.

Further, performing hash encryption on the binary string of the secret information based on the sender's symmetric key described in step 3 is as follows:

Step 3.1. The hash function repeats NC times to copy the key binary string to form a hash bit. The NC calculation formula is as follows:

In the formula, LS is the length of the secret information, in characters; LSK is the length of the key binary string, in bits;

Step 3.2, the hash function generates the hashed secret information binary string according to the hash bit or the secret information binary string.

Further, the binary string of the secret information after hash encryption described in step 4 is replaced with the Unicode zero-width control character by the set rule, as follows:

Divide each consecutive 2 bits of the binary string into a group, replace "00", "01", "10", "11" in each group with "0x200C", "0x202C", "0x202D" respectively, "0x200E", thus forming an invisible string.

Further, the receiver described in step 5 detects the zero-width character string in the carrier text, and restores the binary character string according to the set rule, as follows:

The receiver detects the zero-width string in the carrier text, and restores the binary string according to the rules of "0x200C", "0x202C", "0x202D", "0x200E" corresponding to "00", "01", "10", "11" .

Further, obtaining the receiver's key described in step 6 is as follows:

Step 6.1. The hash function uses the receiving time as the receiver's key, and omits the fourth digit of the time;

Step 6.2. Create a number and convert it to an 8-bit binary string, the receiver key.

Further, performing hash decoding on the binary string based on the receiver's key pair described in step 7 is as follows:

Calculate NC according to formula (4), and copy the NC secondary key binary string to form a hash bit set, and perform XOR calculation with the hash bit bit and the secret information binary string to be decrypted.

Further, the authentication described in step 8 and the decoding of the Gödel function are performed, and the secret information is output, as follows:

Compare whether the decoded sender's key and the receiver's key are the same. If they are the same, perform Gödel function decoding on the binary string of the secret information, and then output the secret information; if they are different, it indicates that the extraction of the secret information failed.

Compared with the prior art, the present invention has the following significant advantages: (1) it can hide a large number of secret messages in the short cover message, and the embedded information is invisible, which improves the confidentiality of secret information; (2) utilizes The intelligent double encoding and encryption of secret information improves the transmission security and convenience of text secret information; (3) Combining mathematical function encoding and symmetric key encryption algorithm, the encrypted strings of secret information generated at different times are different , can defend against a variety of network attacks.

Description of drawings

FIG. 1 is a schematic flow chart of a method for hiding and extracting text secret information based on Unicode encoding according to the present invention.

FIG. 2 is an application scene diagram of text information hiding of the present invention.

FIG. 3 is a schematic flowchart of text secret information hiding in an embodiment of the present invention.

Detailed ways

In conjunction with Fig. 1, the present invention is based on the text secret information hiding and extraction method of Unicode encoding, and the steps are:

Step 1. The sender replaces each character of the secret message with a binary string using the Gödel function encoding;

Step 2. Obtain the sender's symmetric key and combine it in front of the secret information binary string;

Step 3, hashing and encrypting the binary string of the secret information based on the sender's symmetric key;

Step 4. Replace the hash-encrypted binary string of secret information with Unicode zero-width control characters with the set rules to form an invisible string and embed it in front of the cover text;

Step 5. The receiver detects the zero-width character string in the carrier text, and restores the binary character string according to the set rule;

Step 6. Obtain the recipient's key;

Step 7, hash decoding the binary string based on the receiver key;

Step 8: Authenticate and decode the Gödel function, and output the secret information.

Further, the sender described in step 1 replaces each character of the secret information with a binary string using Gödel function encoding, as follows:

Step 1.1. Set η to be any given number, then there is a unique solution <α, β>, let η be the ASCII code of the letter, then <α, β> is the unique number pair of each character of SM:

< ^α ,β>=2α(2β+1)-1 (1)

and 2 ^α (2β+1)≠0

in, is a natural number, exists Let 2α×k ⁼ η+1.

In equation (2), is an odd number;

The embedding algorithm uses equations (2) and (3) to compute <α,β> pairs for each character of the secret message;

Step 1.2. Convert α and β into 6-bit binary strings respectively, and connect them together to generate a 12-bit binary string for each letter;

Step 1.3, splicing the binary strings of each letter together to form a binary string of secret information.

Further, obtaining the sender's symmetric key described in step 2 is combined in front of the secret information binary string, as follows:

Step 2.1. The hash function uses the sending time, that is, the time when the hidden information is generated, as the sender's key, and omits the fourth bit of the time;

Step 2.2. Create a number and convert the number into an 8-bit binary string, that is, the sender's key, which is combined in front of the secret message binary string.

Further, performing hash encryption on the binary string of the secret information based on the sender's symmetric key described in step 3 is as follows:

Step 3.1. The hash function repeats NC times to copy the key binary string to form a hash bit. The NC calculation formula is as follows:

In the formula, LS is the length of the secret information, in characters; LSK is the length of the key binary string, in bits;

Step 3.2, the hash function generates the hashed secret information binary string according to the hash bit or the secret information binary string.

Further, the binary string of the secret information after hash encryption described in step 4 is replaced with the Unicode zero-width control character by the set rule, as follows:

Divide each consecutive 2 bits of the binary string into a group, replace "00", "01", "10", "11" in each group with "0x200C", "0x202C", "0x202D" respectively, "0x200E", thus forming an invisible string.

Further, the receiver described in step 5 detects the zero-width character string in the carrier text, and restores the binary character string according to the set rule, as follows:

The receiver detects the zero-width string in the carrier text, and restores the binary string according to the rules of "0x200C", "0x202C", "0x202D", "0x200E" corresponding to "00", "01", "10", "11" .

Further, obtaining the receiver's key described in step 6 is as follows:

Step 6.1. The hash function uses the receiving time as the receiver's key, and omits the fourth digit of the time;

Step 6.2. Create a number and convert it to an 8-bit binary string, the receiver key.

Further, performing hash decoding on the binary string based on the receiver's key pair described in step 7 is as follows:

Calculate NC according to formula (4), and copy the NC secondary key binary string to form a hash bit set, and perform XOR calculation with the hash bit bit and the secret information binary string to be decrypted.

Further, the authentication described in step 8 and the decoding of the Gödel function are performed, and the secret information is output, as follows:

Compare whether the decoded sender's key and the receiver's key are the same. If they are the same, perform Gödel function decoding on the binary string of the secret information, and then output the secret information; if they are different, it indicates that the extraction of the secret information failed.

The present invention will be described in detail below in conjunction with the embodiments.

Example

The specific scene diagram of the embedding of text hidden information and detection and extraction is shown in Figure 2, where SM represents secret information, CM represents cover text, key is the key, and CM _HM is the text containing the secret information. Cover text and secret information. After the secret information is processed, the hidden secret information is embedded in the cover text, and then the carrier text containing the hidden information is transmitted to the receiver through social media or SMS; the receiver enters the carrier text to be detected, Use the key to decrypt the first layer, and then perform the comparison key authentication. If the authentication is successful, output the secret information, otherwise it will prompt that the secret extraction fails. Combined with the flowchart in Figure 1, the specific steps are as follows:

Step 1. The sender replaces each character of the secret message with a binary string using the Gödel function encoding, as follows:

Step 1.1. Set η to be any given number, then there is a unique solution <α, β>, let η be the ASCII code of the letter, then <α, β> is the unique number pair of each character of SM:

< ^α ,β>=2α(2β+1)-1 (1)

and

In equation (2), is an odd number;

The embedding algorithm uses equations (2) and (3) to compute <α,β> pairs for each character of the secret message;

For example, the ASCII code of "z" is 122, that is, n=122. First, by calculating the maximum number of to obtain α:

Step 1.2. Convert α and β into 6-bit binary strings respectively, and connect them together to generate a 12-bit binary string for each letter;

Step 1.3, splicing the binary strings of each letter together to form a binary string of secret information.

Step 2. Obtain the sender's symmetric key and combine it in front of the secret information binary string, as follows:

Step 2.1. Use the hash function to use the sending time, that is, the time when the hidden information is generated, as the sender's key, such as "10:12", and omit the fourth bit of the time;

Step 2.2. Create a number, such as "101", and convert it into an 8-bit binary string, which is the sender's key, and combine it in front of the secret message binary string.

Step 3. Hash and encrypt the binary string of the secret information based on the sender's symmetric key, as follows:

Step 3.1. The hash function repeats NC times to copy the key binary string to form a hash bit. The NC calculation formula is as follows:

In the formula, LS is the length of the secret information, in characters; LSK is the length of the key binary string, in bits;

Step 3.2, the hash function generates the hashed secret information binary string according to the hash bit or the secret information binary string.

Step 4. Replace the hash-encrypted binary string of secret information with Unicode zero-width control characters using the set rules to form an invisible string and embed it in front of the cover text, as follows:

Combined with the example of text secret information hiding in Figure 3, each consecutive 2 bits of the binary string are divided into a group, and "00", "01", "10", and "11" in each group are respectively replaced with "0x200C", "0x202C", "0x202D", "0x200E", the replacement scheme is shown in Table 1:

Table 1 Unicode zero-width character table and replacement scheme

Step 5. The receiver detects the zero-width character string in the carrier text, and restores the binary string according to the set rules, as follows: Detecting the zero-width character string in the carrier text, according to "0x200C", "0x202C", "0x202D" , "0x200E" corresponds to "00", "01", "10", "11" rules to restore binary strings.

Step 6. Obtain the receiver's key, as follows:

Step 6.1. The hash function uses the receiving time as the receiver's key, such as "10:12", and omits the fourth bit of the time;

Step 6.2. Create a number, such as "101", and convert it into an 8-bit binary string, which is the receiver's key.

Step 7, Step 7, hash decoding the binary string based on the receiver key, as follows:

Calculate NC according to formula (4), and copy the NC secondary key binary string to form a hash bit, and perform XOR calculation with the binary string of secret information to be decrypted.

Step 8: Authenticate and decode the Gödel function, and output the secret information, as follows:

Compare whether the decoded sender's key and the receiver's key are the same. If they are the same, perform Gödel function decoding on the binary string of the secret information, and then output the secret information; if they are different, it indicates that the extraction of the secret information failed.

The invention can hide a large number of secret messages in the short cover message, and the embedded information is invisible, which improves the confidentiality of the secret information; the intelligent double encoding and encryption of the secret information improves the transmission security of the text secret information It combines mathematical function encoding and symmetric key encryption algorithm, and the encrypted strings of secret information generated at different times are different, which can resist various network attacks.

Claims (9)

1. A text secret information hiding and extracting method based on Unicode coding is characterized by comprising the following steps:

step 1, a sender replaces each character of secret information with a binary character string by using Godel function coding;

step 2, obtaining a symmetric key of a sender, and combining the symmetric key of the sender in front of the binary string of the secret information;

step 3, carrying out hash encryption on the secret information binary character string based on the symmetric key of the sender;

step 4, replacing the binary character string of the hashed and encrypted secret information with a Unicode zero-width control character according to a set rule to form an invisible character string and embedding the invisible character string in front of a cover text;

step 5, the receiving party detects the zero-width character string in the carrier text and restores the binary character string according to a set rule;

step 6, acquiring a key of a receiver;

step 7, carrying out hash decoding on the binary string based on the key of the receiving party;

and 8, authenticating, decoding the Godel function, and outputting the secret information.

2. The method for hiding and extracting text secret information based on Unicode encoding as claimed in claim 1, wherein the sender in step 1 replaces each character of the secret information with a binary string by using Godel function encoding, specifically as follows:

step 1.1, setting η to any given number, there is a unique solution < α, β >, let η be the ASCII code of the alphabet, then < α, β > is the unique number pair per character of SM:

<α，β>＝2^α(2β+1)-1 (1)

and 2 is^α(2β+1)≠0

Where N is a natural number, there is k ∈ N, such that 2^α×k＝η+1；

In the equation (2), the process is carried out,is odd;

the embedding algorithm calculates the < α, β > pair for each character of the secret information using equations (2) and (3);

step 1.2, respectively converting alpha and beta into 6-bit binary character strings, connecting the 6-bit binary character strings together, and generating a 12-bit binary character string for each letter;

and 1.3, splicing the binary character strings of each letter together to form the binary character string of the secret information.

3. The method for hiding and extracting text secret information based on Unicode encoding of claim 1, wherein the step 2 of obtaining the symmetric key of the sender is combined in front of the binary string of the secret information, specifically as follows:

step 2.1, the hash function takes the sending time, namely the time for generating the hidden information, as a sender secret key, and omits the 4 th bit of the time;

step 2.2, create a number and convert the number into an 8-bit binary string, i.e. the sender key, which is combined before the secret information binary string.

4. The method for hiding and extracting text secret information based on Unicode encoding of claim 1, wherein the step 3 hash-encrypts the binary string of secret information based on the symmetric key of the sender as follows:

step 3.1, the hash function repeats NC times copying the key binary string to form a hash position, and the NC calculation formula is as follows:

wherein LS is the length of the secret information and the unit is character; LSK is the length of the binary string of the key, and the unit is bit;

and 3.2, generating a hashed secret information binary character string by the hash function according to the hash position bit or the secret information binary character string.

5. The method for hiding and extracting text secret information based on Unicode encoding according to claim 1, wherein the step 4 replaces the binary string of the hashed and encrypted secret information with Unicode zero-width control characters by a set rule, specifically as follows:

each consecutive 2 bits of the binary string are divided into one small group, and "00", "01", "10", "11" in each small group are replaced with "0 x 200C", "0 x 202C", "0 x 202D", "0 x 200E", respectively, to form an invisible string.

6. The method for hiding and extracting text secret information based on Unicode encoding according to claim 1, wherein the receiving party detects a zero-width string in the carrier text and restores the binary string according to a set rule as follows:

the receiver detects the zero-width character string in the carrier text, and restores the binary character string according to the rule of "0 x 200C", "0 x 202C", "0 x 202D" and "0 x 200E" corresponding to "00", "01", "10" and "11".

7. The method for hiding and extracting text secret information based on Unicode encoding according to claim 1, wherein the step 6 of obtaining the receiver key specifically comprises the following steps:

step 6.1, the hash function takes the receiving time as a key of a receiving party and omits the 4 th bit of the time;

step 6.2, create a number and convert it into an 8-bit binary string, i.e. the receiver key.

8. The method for hiding and extracting text secret information based on Unicode encoding according to claim 1, wherein the step 7 hash-decodes the binary string based on the key pair of the receiving party as follows:

and (4) calculating NC according to a formula (4), copying the NC-time key binary character string to form a hash bit, and performing exclusive-OR calculation on the hash bit and the secret information binary character string to be decrypted.

9. The method for hiding and extracting text secret information based on Unicode encoding according to claim 1, wherein the authentication in step 8 is performed and the goldel function decoding is performed to output the secret information, specifically as follows:

comparing whether the decoded key of the sender is the same as the key of the receiver, if so, performing Godel function decoding on the binary string of the secret information, and then outputting the secret information; and if the two are different, prompting that the secret information extraction fails.