CN116032509A

CN116032509A - Mail encryption and decryption method and device

Info

Publication number: CN116032509A
Application number: CN202111256524.3A
Authority: CN
Inventors: 王子浩; 张森
Original assignee: China Mobile Communications Group Co Ltd; China Mobile Xiongan ICT Co Ltd; China Mobile System Integration Co Ltd
Current assignee: China Mobile Communications Group Co Ltd; China Mobile Xiongan ICT Co Ltd; China Mobile System Integration Co Ltd
Priority date: 2021-10-27
Filing date: 2021-10-27
Publication date: 2023-04-28
Anticipated expiration: 2041-10-27
Also published as: CN116032509B

Abstract

The application provides a mail encryption and decryption method, a mail encryption and decryption device, electronic equipment and a computer program product, wherein the mail encryption and decryption method comprises the following steps: converting the mail ciphertext into a coding sequence by adopting a preset compression algorithm; style configuration is carried out on the plaintext of the mail based on a preset encryption comparison table and the coding sequence, and information of a copy person is generated; and sending the mail plaintext to a mail receiver according to the information of the transcriber. According to the embodiment of the invention, the text style information of the plaintext and the information of the transcriber of the mail are adopted to carry out steganography on the ciphertext of the mail, the server is not required to host the secret key information, the safety of the encrypted mail is effectively improved, and meanwhile, the corresponding plaintext is reserved in the mail, so that the encryption behavior of the mail is not easy to be perceived, and the disguising property of the encrypted mail is effectively improved.

Description

Mail encryption and decryption method and device

Technical Field

The present invention relates to the field of mail encryption technology, and in particular, to a method and an apparatus for encrypting and decrypting a mail, an electronic device, and a computer program product.

Background

With the high development of social electronic informatization, the use of electronic mail is increasing. The demands for confidentiality of information are also increasing. There are two general schemes for sending secret mail: 1. the mail platform provides encryption technology, a mail sender establishes a string of open mail passwords, and a mail receiver acquires mail information by inputting the passwords. 2. The sender encrypts the sent mail through a conventional encryption algorithm, and the receiver receives the mail and then carries out a decryption algorithm to obtain mail content information.

If the encryption technology provided by the mail platform is used, the following problems exist: the mail ciphertext information in the mail is stored in the mail platform, encryption and decryption are carried out at the server side, and once the mail platform has security problems (such as the attack of the mail server, the information leakage of the mail account and the like), the mail ciphertext in the mail can be stolen. E.g. e-mail encryption using identity based cryptographic techniques, the principle is to use the public identity information of the user (e.g. e-mail address, IP address, name … …, etc.) as a public key of the user, which private key is generated by a trusted center called private key generator, but under this mechanism, the user's secret key is hosted at the server side, and the security of the user's information is also dependent on the security of the server itself and the promise of the service provider.

If the mail is sent using a conventional text encryption algorithm, the security of the mail ciphertext depends on the encryption algorithm. For example, the algorithm of symmetric encryption is used for encrypting by using the hash functions of MD5, SHA1 and SHA25, and the security is gradually reduced as the modern computer has stronger calculation power and lower cost for performing the collision test; and by using asymmetric encryption algorithms such as RSA, elgamal, knapsack algorithm, rabin and the like, the problems of complex algorithm, high complexity of public and private key operation, long operation time consumption and the like are faced. In addition, the encrypted mail ciphertext usually looks like a pile of codes, encryption behaviors are easy to perceive, disguise is insufficient, and once the mail is stolen by a third party, the third party can reversely deduce the algorithm used by the third party through the code length and the rule of the encrypted mail content, so that the risk of decryption still exists.

Disclosure of Invention

The embodiment of the application provides a mail encryption and decryption method, a mail encryption and decryption device, electronic equipment and a computer program product, which are used for solving the technical problems of insufficient disguise and insufficient security of the conventional mail encryption method.

In a first aspect, an embodiment of the present application provides a mail encryption method, including:

converting the mail ciphertext into a coding sequence by adopting a preset compression algorithm;

style configuration is carried out on the plaintext of the mail based on a preset encryption comparison table and the coding sequence, and information of a copy person is generated;

and sending the mail plaintext to a mail receiver according to the information of the transcriber.

In one embodiment, the encryption lookup table includes a font style lookup table, a transcriber address character table, and a transcriber domain name lookup table; the style configuration of the mail plaintext based on the preset encryption comparison table and the coding sequence and the generation of the information of the copy person comprise the following steps:

intercepting a first coding sequence from the coding sequences, and carrying out style configuration on the mail plaintext based on the font style comparison table and the first coding sequence;

and taking the sequences except the first coding sequence in the coding sequences as a second coding sequence, and generating the information of the transcriber based on the transcriber address character table, the transcriber domain name comparison table and the second coding sequence.

In one embodiment, the generating the transcriber information based on the transcriber address character table, the transcriber domain name lookup table, and the second coding sequence with the sequence other than the first coding sequence as the second coding sequence includes:

and converting the second coding sequence into comparison parameters according to a preset conversion algorithm, extracting characters from the transcriber address character table according to the comparison parameters to form a transcriber prefix, extracting a transcriber domain name from the transcriber domain name comparison table, and generating the transcriber information according to the transcriber prefix and the transcriber domain name.

In one embodiment, the converting the second coding sequence into a comparison parameter according to a preset conversion algorithm, extracting characters from the transcriber address character table according to the comparison parameter to form a transcriber prefix, extracting a transcriber domain name from the transcriber domain name comparison table, and generating the transcriber information according to the transcriber prefix and the transcriber domain name, including:

dividing the second coding sequence into a plurality of groups of coding subsequences by taking the character length of the mail plaintext as the dividing length;

Dividing each group of coding subsequences into a front subsequence and a rear subsequence, converting the front subsequence into a first comparison parameter according to a preset conversion algorithm, and converting the rear subsequence into a second comparison parameter according to the conversion algorithm;

and extracting characters from the copying person address character table according to the first comparison parameters to form a copying person prefix, extracting a copying person domain name from the copying person domain name comparison table according to the second comparison parameters, and generating the copying person information according to the copying person prefix and the copying person domain name.

In a second aspect, an embodiment of the present application provides a mail decrypting method, including:

based on a pre-stored encryption comparison table, analyzing the information of the copy person of the mail and the text style information of the plaintext of the mail to obtain a coding sequence;

and converting the coding sequence according to a pre-stored decompression algorithm to obtain a mail ciphertext.

In one embodiment, the encryption reference table includes a font style reference table, a transcriber address character table and a transcriber domain name reference table, and the parsing the transcriber information of the mail and the text style information of the plaintext of the mail to obtain the coding sequence based on the pre-stored encryption reference table includes:

Analyzing text style information of a mail plaintext based on the font style comparison table to obtain a first coding sequence;

analyzing the information of the copying person of the mail based on the copying person address character table and the copying person domain name comparison table to obtain a second coding sequence;

and combining the first coding sequence and the second coding sequence to obtain the coding sequence.

In a third aspect, an embodiment of the present application provides a mail encryption apparatus, including:

the code generation module is used for converting the mail ciphertext into a code sequence by adopting a preset compression algorithm;

the mail steganography module is used for carrying out style configuration on a mail plaintext based on a preset encryption comparison table and the coding sequence and generating information of a transcriber;

and the mail sending module is used for sending the mail plaintext to a mail receiver according to the information of the transcriber.

In a fourth aspect, an embodiment of the present application provides a mail decrypting apparatus, including:

the code analysis module is used for analyzing the information of the transcriber of the mail and the text style information of the plaintext of the mail based on a pre-stored encryption comparison table to obtain a code sequence;

and the mail decryption module is used for converting the coding sequence according to a pre-stored decompression algorithm to obtain a mail ciphertext.

In a fifth aspect, an embodiment of the present application provides an electronic device, including a processor and a memory storing a computer program, where the processor implements the steps of the mail encryption method described in the first aspect or the steps of the mail decryption method described in the second aspect when executing the program.

In a sixth aspect, embodiments of the present application provide a computer program product comprising a computer program which, when executed by a processor, implements the steps of the mail encryption method described in the first aspect or the steps of the mail decryption method described in the second aspect.

According to the mail encryption and decryption method, device, electronic equipment and computer program product, the text style information of the plaintext and the information of the copy person of the mail are adopted to carry out steganography on the mail ciphertext, the server does not need to host secret key information, the safety of encrypted mail is effectively improved, meanwhile, the corresponding plaintext is reserved in the mail, so that the encryption behavior of the mail is not easy to be perceived, and the disguising performance of the encrypted mail is effectively improved.

Drawings

For a clearer description of the present application or of the prior art, the drawings that are used in the description of the embodiments or of the prior art will be briefly described, it being apparent that the drawings in the description below are some embodiments of the present application, and that other drawings may be obtained from these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic flow chart of a mail encryption method according to an embodiment of the present application;

fig. 2 is a schematic flow chart of a mail decryption method according to an embodiment of the present application;

FIG. 3 is a second flow chart of the mail encryption method according to the embodiment of the present application;

FIG. 4 is a second flowchart of a mail decrypting method according to an embodiment of the present disclosure;

fig. 5 is a schematic structural diagram of a mail encryption device provided in an embodiment of the present application;

fig. 6 is a schematic structural diagram of a mail decrypting apparatus provided in the embodiment of the present application;

fig. 7 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

Detailed Description

For the purposes of making the objects, technical solutions and advantages of the present application more apparent, the technical solutions in the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

Fig. 1 is a schematic flow chart of a mail encryption method according to an embodiment of the present application. Referring to fig. 1, an embodiment of the present application provides a mail encryption method, which may include:

S1, converting a mail ciphertext into a coding sequence by adopting a preset compression algorithm;

s2, carrying out style configuration on the plaintext of the mail based on a preset encryption comparison table and a coding sequence, and generating information of a copy person;

and S3, sending the mail plaintext to a mail receiver according to the information of the transcriber.

In this embodiment, a preset compression algorithm is first adopted to convert the mail ciphertext into a code sequence, for example, a binary sequence.

According to a preset encryption comparison table, the text style information of the plaintext and the information of the copy person of the mail can be adopted to carry out steganography on the ciphertext of the mail. For example, comparing the code sequence with an encryption reference table to perform font format setting on plain text, information of the code sequence is steganographically in plain text (text format information); in addition, the coding sequence is compared with the encryption comparison table to generate the information of the transcriber, and the information of the coding sequence is hidden in the information of the transcriber. In a specific embodiment, the style of each font of the plaintext may utilize similar fonts and colors, so as to further improve camouflage performance of the mail encryption behavior, for example, the fonts may adopt "Song Ti" and "new Song Ti", and the adopted font colors RGB are similar styles such as (0, 0) and (1, 1).

After the ciphertext is subjected to steganography to complete encryption of the mail, the plaintext with the specific style is used as mail content, and then the encrypted mail is sent to a mail receiver. It can be understood that even if the mail is intercepted by an attacker, the intercepted mail is only the plaintext part of the mail, the actual ciphertext information cannot be obtained, and the encrypted mail is effectively ensured; and because of the existence of the plaintext, an attacker cannot perceive that the mail is encrypted and hidden, so that the disguising performance of encryption behavior is greatly improved. In addition, it should be noted that, the address of the receiver of the mail is still according to the address actually filled by the sender, and the information of the transcriber is only the hidden writing information used as the ciphertext and is sent to the receiver, so that the receiver of the mail analyzes the received plaintext (text style information) and the information of the transcriber based on the prestored encryption comparison table (consistent with the encryption comparison table of the sender) to obtain the coding sequence of the ciphertext, and further calculates the coding sequence according to the prestored decompression algorithm (corresponding to the compression algorithm of the sender and understood as the inverse operation).

According to the mail encryption method, the text style information of the plaintext and the information of the copy person of the mail are adopted to carry out steganography on the ciphertext of the mail, the server does not need to host key information, the safety of the encrypted mail is effectively improved, meanwhile, the corresponding plaintext is reserved in the mail, so that the encryption behavior of the mail is not easy to be perceived, and the disguising performance of the encrypted mail is effectively improved. In addition, the encryption and decryption algorithm of the embodiment of the application is simple, low in algorithm complexity, low in cost and difficult to decipher, and is a convenient, quick and safe encryption method.

In one embodiment, the encryption lookup table includes a font style lookup table, a transcriber address character table, and a transcriber domain name lookup table; further, step S2 may include:

s21, intercepting a first coding sequence from the coding sequences, and carrying out style configuration on the plaintext of the mail based on a font style comparison table and the first coding sequence;

s22, taking the sequences except the first code sequence in the code sequences as second code sequences, and generating the information of the transcriber based on the transcriber address character table, the transcriber domain name comparison table and the second code sequences.

It should be noted that the encryption reference table may include a font style reference table, a transcriber address character table, and a transcriber domain name reference table. Then the coding sequence of the ciphertext can be divided into two parts, one part is used for comparing with a font style comparison table to select a corresponding font style to set the style of the plaintext, and the other part is used for comparing with a transcriber address character table and a transcriber domain name comparison table to extract corresponding transcriber address information. The first part of the code sequence may be a code sequence with the same number of characters as that of the plaintext, so that each bit code is used to set the font style of each character correspondingly. In other embodiments, an indefinite number of bit code sequences may be used to set the font style of the plaintext, such as setting the style of each two codes for one plaintext font, etc.

It will be appreciated that the first code sequence may be truncated from any position of the code sequence, and that in order to simplify the encryption process, the corresponding first code sequence may be truncated from the head of the code sequence. However, it should be noted that, no matter which part of the coding sequence is intercepted as the first coding sequence, the second coding sequence is necessarily the remaining coding sequence except the first coding sequence, so that all the coding sequences can participate in the steganography of the ciphertext without repeated participation, thereby enabling the encryption and decryption processes to be aligned more neatly and avoiding the ciphertext translation error.

According to the mail encryption method provided by the embodiment of the application, the encryption comparison table is divided into the font style comparison table, the copy person address character table and the copy person domain name comparison table, the coding sequence is further divided into the first coding sequence and the second coding sequence, and the first coding sequence and the second coding sequence are respectively subjected to the steganography of ciphertext information, so that the efficiency and the accuracy of the mail encryption process can be effectively improved.

In one embodiment, further, S22 may include:

s221, converting the second coding sequence into comparison parameters according to a preset conversion algorithm, extracting characters from a copying person address character table according to the comparison parameters to form a copying person prefix, extracting a copying person domain name from a copying person domain name comparison table, and generating copying person information according to the copying person prefix and the copying person domain name.

It should be noted that, obtaining the second code sequence may be tedious and complex, and the corresponding steganographic information cannot be simply and uniquely obtained from the encryption reference table, so that the second code sequence may be simplified by adopting a preset conversion algorithm. For example, the second code sequence is equally divided into several groups, the code of each group is divided into integer or remainder to obtain the number, and the numbers are used to compare with the encryption comparison table to obtain the corresponding content as the information of the transcriber.

According to the mail encryption method provided by the embodiment of the application, the second coding sequence is converted into the comparison parameters by adopting the conversion algorithm, and the comparison parameters are adopted to generate the information of the copy person in comparison from the preset encryption comparison table, so that the complexity of the encryption comparison table can be simplified, and the encryption efficiency is further improved.

In one embodiment, further, S221 may include:

s2211, taking the character length of a mail plaintext as a dividing length, and dividing a second coding sequence into a plurality of groups of coding subsequences;

s2212, dividing each group of coding subsequences into a front subsequence and a rear subsequence, converting the front subsequence into a first comparison parameter according to a preset conversion algorithm, and converting the rear subsequence into a second comparison parameter according to the conversion algorithm;

S2213, extracting characters from the copying person address character table according to the first comparison parameters to form a copying person prefix, extracting the copying person domain name from the copying person domain name comparison table according to the second comparison parameters, and generating copying person information according to the copying person prefix and the copying person domain name.

When the second code sequences are grouped, the length of each group of codes may be set to the length of the characters in the plain text. Each group of coding subsequences corresponds to one copy person information, wherein, for each group of coding subsequences, the coding subsequences can be divided into a front subsequence and a rear subsequence, the front subsequence is used for comparing with a copy person address character table to extract characters to form a copy person prefix, the rear subsequence is used for comparing with a copy person domain name comparison table and extracting a copy person domain name, and then the copy person prefix and the copy person domain name are combined to generate the copy person information of the group of coding subsequences.

According to the mail encryption method provided by the embodiment of the application, the second coding sequences are grouped, each group of coding subsequences is divided into the front subsequence and the rear subsequence, and the prefix of the person to be sent and the domain name of the person to be sent are obtained by comparison, so that the complexity of an encryption comparison table can be further simplified, and the mail encryption efficiency is further improved.

Fig. 2 is a flow chart of a mail decryption method according to an embodiment of the present application. Referring to fig. 2, an embodiment of the present application provides a mail decrypting method, including:

s1, analyzing information of a person copying the mail and text style information of a plaintext of the mail based on a pre-stored encryption comparison table to obtain a coding sequence;

s2, converting the coding sequence according to a pre-stored decompression algorithm to obtain a mail ciphertext.

It should be noted that, the decryption process in the embodiment of the present application and the mail encryption process in the above embodiment may be understood as inverse operations. Firstly, based on a pre-stored encryption comparison table, analyzing the information of the person copying the mail and the text style information of the plaintext of the mail to obtain a coding sequence of the ciphertext. The encryption comparison table is consistent with the encryption comparison table used by the sender for encrypting the mail. And then calculating the ciphertext code sequence obtained by analysis by utilizing a pre-stored decompression algorithm (corresponding to a compression algorithm of a sender and understood to be mutually inverse operation) so as to obtain the mail ciphertext information.

According to the mail decryption method, the pre-stored encryption comparison table is adopted to analyze the information of the person copying the mail and the text style information of the plaintext of the mail to obtain the coding sequence of the ciphertext, and then the pre-stored decompression algorithm is adopted to analyze the ciphertext information of the mail, so that the secret key information of the mail is not required to be managed through a server, the safety of the encrypted mail is effectively improved, and meanwhile, the corresponding plaintext is reserved in the mail, so that the encryption behavior of the mail is not easy to be perceived, and the disguising performance of the encrypted mail is effectively improved.

In one embodiment, the encryption lookup table includes a font style lookup table, a transcriber address character table, and a transcriber domain name lookup table, and step S1 may include:

s11, analyzing text style information of a plaintext of the mail based on a font style comparison table to obtain a first coding sequence;

s12, analyzing the information of the copy person of the mail based on the copy person address character table and the copy person domain name comparison table to obtain a second coding sequence;

s13, combining the first coding sequence and the second coding sequence to obtain a coding sequence.

In the embodiment of the application, the mail receiver compares the text style information of the obtained mail plaintext with a font style comparison table and analyzes a corresponding first coding sequence; and according to the information of the copying person of the mail, the corresponding second coding sequence is analyzed by comparing with the address character table of the copying person and the domain name comparison table of the copying person, and the complete ciphertext coding sequence is obtained by combining according to the decryption strategy corresponding to the encryption strategy of the sender.

According to the mail decryption method, the encryption comparison table is divided into the font style comparison table, the copy person address character table and the copy person domain name comparison table, the first coding sequence and the second coding sequence are respectively obtained through analysis according to the text style information of the plaintext of the mail and the copy person information of the mail, and then the first coding sequence and the second coding sequence are obtained through splicing and combining, so that the efficiency and the accuracy of the mail decryption process can be effectively improved.

In one embodiment, further, step S12 may include:

s121, decomposing the information of the copy person of the mail into a copy person prefix and a copy person domain name, comparing and analyzing a first comparison parameter according to the copy person prefix and a copy person address character table, comparing and analyzing a second comparison parameter according to the copy person domain name and a copy person domain name comparison table, and reversely calculating a second coding sequence according to the first comparison parameter and the second comparison parameter.

According to the mail decryption method provided by the embodiment of the application, the information of the copying person is divided into the copying person prefix and the copying person domain name, the first comparison parameter and the second parameter are respectively analyzed, and the second coding sequence is reversely calculated according to the first comparison parameter and the second comparison parameter, so that the complexity of an encryption comparison table (the copying person address character table and the copying person domain name comparison table) can be simplified, and the decryption efficiency is further improved.

Referring to fig. 3 to fig. 4, based on the above-mentioned scheme, in order to better understand the mail encryption method and the mail decryption method provided by the present invention, the following details are given by way of specific examples:

1. the mail sender and the mail receiver need to acquire a common encryption comparison table, including a font style comparison table, a transcriber address character table and a transcriber domain name comparison table. The specific mode of realizing the step can be realized by presetting related menus of the APP or the plug-in gadget;

2. The encryption program of the mail sender compresses the ciphertext to be sent through a compression algorithm to obtain a binary sequence;

3. the encryption program of the mail sender writes a plaintext of a ciphertext carrier, wherein the plaintext can be a section of text which accords with language logic and is automatically generated by the program, such as a news draft of a certain news or a chapter paragraph of a certain novel, or can be a user-defined sentence paragraph, and the text can be realized by setting an APP or a plug-in widget;

4. binary codes are obtained according to a compression algorithm and are applied to a comparison table, and a plaintext style is set in a correlated manner;

5. and acquiring information of the transcriber according to a specific conversion algorithm. The information of the transcriber is determined by four parameters x, y, z1 and z2, wherein x and y are corresponding characters found from a comparison table and are spliced to be used as the address of the transcriber; the z1, z2 value is the corresponding mailbox domain address found from the lookup table. According to the proposed algorithm, the z2 has a value of z1 which is invalid, so that the x, y, z1 (or x, y, z 2) is spliced together to form the xy@z1 (or xy@z2) which is the domain name of the transcriber address.

6. The mail receiving side decryption program reversely calculates ciphertext information according to the text style information and the information of the copying person in the received mail.

With continued reference to fig. 3 to 4, the following embodiments are provided:

1. the mail sender and the mail receiver need to have a common encryption comparison table, and the specific comparison table is as follows: font style lookup table, transcriber address character table, transcriber domain name lookup table. The following table is used by way of example only and is not limiting. Assuming that the font style comparison table adopts two colors and two fonts, the reference table corresponds to various styles when key values are 0 and 1, and the specific use mode of the comparison table can be as follows: when a certain key value appears for the first time, a pattern of the minimum sequence number i is used, when the subsequent key value appears again, a pattern of the sequence number i+1 is used, if i+1 is larger than the maximum sequence number corresponding to the key value, a pattern of the minimum sequence number is used, and the process is repeated subsequently. Such as "10110". The first character is "1" and "1" is the first appearance, using the pattern of the minimum number 3 corresponding to "1"; the second character is "0", and "0" is the first appearance, using the pattern of the minimum sequence number 1 corresponding to the sequence number "0"; the third digit is "1", at this time "1" does not appear for the first time, the last time the pattern of serial number 3 is used, so this time the pattern of serial number 3+1, namely serial number 4 is used; the fourth number is "1", at which time "1" does not appear for the first time, and because serial number 4+1, i.e., serial number 5, is greater than the maximum serial number corresponding to "1", the pattern of minimum serial number 3 corresponding to "1" is looped back; the fifth number is "0", where "0" does not occur for the first time, using the pattern of sequence number 1+1, namely sequence number 2.

The following font styles are adopted in the embodiment of the application, the color RGB (0, 0) and the color RGB (1, 1) are two kinds of black with very similar colors, and the Song Ti and the new Song body are two kinds of fonts with very similar colors.

Font style look-up table (the number of fonts and the number of colors can be adjusted):

sequence number	Key value	Style of
			1	0	Song Ti + color RGB (0, 0)
2	0	Song Ti + color RGB (1, 1)
			3	1	New Song Ti + colour RGB (0, 0)
4	1	New Song Ti + colour RGB (1, 1)

The address character table x of the sender (the specific content can be adjusted according to actual needs):

the address character table y of the person to be copied (the specific content can be adjusted according to actual needs, and the table is the same as the address character table x of the person to be copied):

the sender domain name comparison table z1:

the sender domain name comparison table z2 (the specific content can be adjusted according to the need):

serial number (z 2 value)	Domain name set
		0	whut.edu
1	hzut.edu
		2	whu.edu
3	hne.edu
		4	wqus.edu
5	cqu.edu
		6	shhu.edu
7	bjju.edu
		8	bjds.edu
9	qweu.edu
		10	ytw.edu
11	clsu.edu

2. The encryption program of the mail sender compresses the ciphertext to be sent to obtain a binary sequence;

and 2, acquiring a binary sequence after ciphertext compression by using a compression algorithm. Assume here that the ciphertext to be transmitted is "today's don't want to go" and its compressed counterpart is encoded as 010101100100111101000101010001100101001101001101010110100100101001001.

3. The mail sender encryption program uses plaintext of user input (or system generation), such as: "today weather is good, I want to go shopping". "

4. Binary codes are obtained according to a compression algorithm, and are compared with a font style comparison table for application, and the style of the plaintext is set in a related manner, specifically as follows:

4-1, obtaining the length of the plaintext character in the step 3. Here we obtain that the length of the plaintext is 12.

4-2, cutting out binary codes with the same length as the plaintext characters from the codes in the step 2. The character intercepted here is 010101100100.

4-3, comparing the font style comparison table according to the comparison method introduced in the step 1 according to the intercepted binary code, and setting the font color style of the plaintext.

5. The values of parameters x, y, z1 and z2 are obtained according to a preset conversion algorithm, corresponding characters are found from a 26 alphabet according to the values of x and y and are spliced to be used as the address of a copying person, and corresponding mailbox domain name addresses are found from a comparison table according to the values of z1 and z2, wherein the algorithm is as follows:

5-1, taking the rest binary codes in the step 2, dividing the binary codes into a group of every 12 bits, and finally adding zero to the right side of less than 12 bits to make up, wherein the added bit number is taken as the value of z 2. The remaining binary codes are thus grouped, the last group having only 9 bits and 3 bits are therefore padded with 3 0 bits to 12 bits, so the value of z2 is 3. The encoded packet values are shown below:

Sequence number	Numerical value
		1	111101000101
2	010001100101
		3	001101001101
4	010110100100
		5	101001001000

5-2, dividing each set of binary codes into a first 9 bits W1 and a last 3 bits W2. The code division value table is as follows:

sequence number	Numerical value	W1	W2
					1	111101000101	111101000	101
2	010001100101	010001100	101
				3	001101001101	001101001	101
4	010110100100	010110100	100
				5	101001001000	101001001	000

5-3 values of x, y, z1 are obtained from x=w1/26 (rounding), y=w1% 26 (remainder), z1=w2. The control parameters are shown below:

5-4, finding letters at corresponding positions in the address character table of the sender according to the values of x and y to serve as prefixes of the sender of the mail, and calculating the address of the sender according to the values of z1 and z 2. The sender information table is as follows:

sequence number	x	y	z1	z2	Address of person to be sent
						1	18	20	5	\	su@qq.com
2	5	10	5	\	fk@qq.com
						3	4	1	5	\	eb@qq.com
4	6	24	4	\	gy@gmail.com
						5	12	17	\	3	mr@hne.edu

Thus, the mail sender sends the mail even if encryption of the mail is completed. If the mail is intercepted by an attacker, the intercepted information is also a plaintext part and cannot be intercepted into ciphertext information.

6. The decryption program of the mail receiver reversely calculates ciphertext information according to text style information of plaintext in the received mail and information of a transcriber of the mail. The decryption process is shown in fig. 4.

6-1 the mail receiver inversely calculates the values of x, y, z1, z2 based on the information of the transcriber in the received mail. The table of correspondence between the information of the transcriber and the comparison parameters is as follows:

6-2 binary codes are calculated from x, y, z1, z 2. The conversion table of the comparison parameters and codes is as follows:

Where w1=x 26+y, w2=z1.

6-3, calculating the binary code 010101100100 according to the font style of the plaintext information.

6-4 splice the above codes together to obtain the overall binary code 010101100100111101000101010001100101001101001101010110100100101001001.

6-5 finally obtaining the mail ciphertext information ' no thinking about going out today ' through a decompression algorithm '.

It is understood that implicit encryption means that the information to be expressed is encrypted in a secret way, so that the information still looks as a plaintext, but not as an original text, and has the advantage that the encryption behavior is not easy to find, so that a stealer is more confused. According to the mail encryption method, the ciphertext is subjected to steganography through the fonts, the colors and the transcriber information of the mail text, and particularly, the similar fonts and colors are utilized, so that a stealer cannot easily perceive the ciphertext. For example, the fonts used in plaintext are "Song Ti" and "new Song Ti", and the colors used RGB are (0, 0) and (1, 1). The plain text appears to be indistinguishable from ordinary text, but in reality the meaning expressed may be "no doors are intended today".

It should be noted that, for the same terminal, only an encryption program (as a mail sender) or only a decryption program (as a mail receiver) may be deployed, or both the encryption program and the decryption program may be deployed. In addition, in the specific application, the encryption program or the decryption program can be realized through a mobile phone APP or a plug-in widget, when a user sends and receives mails, the mobile phone terminal can encrypt and decrypt the mail ciphertext through the APP, and the PC terminal can encrypt and decrypt the mail ciphertext through the plug-in widget. It can be appreciated that the method is suitable for application scenarios such as sending and receiving mails in the military, government and enterprises. The method can encrypt and steganographically the internal mails of enterprises or government authorities and the like, and even if an external attacker obtains the mail information through an illegal way, the ciphertext content of the mail cannot be known. The mail encryption and decryption method of the invention can more secretly improve the confidentiality of the mail on the premise of simple encryption and decryption algorithm, low cost and difficult decryption.

It should be noted that, for simplicity of description, the above method or flow embodiments are all described as a series of combinations of acts, but it should be understood by those skilled in the art that the embodiments are not limited by the order of acts described, as some steps may occur in other orders or concurrently in accordance with the embodiments herein. Further, those skilled in the art will appreciate that the embodiments described in the specification are all alternative embodiments, and that the acts referred to are not necessarily required by the embodiments of the present application.

The mail encryption device provided in the embodiment of the present application will be described below, and the mail encryption device described below and the mail encryption method described above may be referred to correspondingly to each other.

Referring to fig. 5, an embodiment of the present application provides a mail encryption device, including:

the code generation module 1 is used for converting the mail ciphertext into a code sequence by adopting a preset compression algorithm;

the mail steganography module 2 is used for carrying out style configuration on a mail plaintext based on a preset encryption comparison table and the coding sequence and generating information of a transcriber;

and the mail sending module 3 is used for sending the mail plaintext to a mail receiver according to the information of the transcriber.

Further, the encryption comparison table comprises a font style comparison table, a transcriber address character table and a transcriber domain name comparison table; the mail steganography module 2 is specifically configured to:

Further, the generating the information of the transcriber based on the transcriber address character table, the transcriber domain name comparison table, and the second coding sequence with the sequence other than the first coding sequence as a second coding sequence includes:

Further, the converting the second coding sequence into a comparison parameter according to a preset conversion algorithm, extracting characters from the address character table of the transcriber according to the comparison parameter to form a prefix of the transcriber, extracting a domain name of the transcriber from the domain name comparison table of the transcriber, and generating the information of the transcriber according to the prefix of the transcriber and the domain name of the transcriber, including:

It can be understood that the embodiment of the device item corresponds to the embodiment of the method item of the present invention, and the mail encryption device provided in the embodiment of the present application may implement the mail encryption method provided in any one of the embodiments of the method item of the present invention.

The mail decryption device provided in the embodiment of the present application will be described below, and the mail decryption device described below and the mail decryption method described above may be referred to correspondingly to each other.

Referring to fig. 6, an embodiment of the present application provides a mail decrypting apparatus, including:

the code analysis module 1 is used for analyzing the information of the copy person of the mail and the text style information of the plaintext of the mail based on a pre-stored encryption comparison table to obtain a code sequence;

and the mail decryption module 2 is used for converting the coding sequence according to a pre-stored decompression algorithm to obtain a mail ciphertext.

The encryption comparison table comprises a font style comparison table, a transcriber address character table and a transcriber domain name comparison table, and the code analysis module 1 is specifically configured to:

It can be understood that the embodiment of the device item corresponds to the embodiment of the method item of the present invention, and the mail decryption device provided in the embodiment of the present application may implement the mail decryption method provided in any one of the embodiments of the method item of the present invention.

Fig. 7 illustrates a physical schematic diagram of an electronic device, as shown in fig. 7, which may include: processor 710, communication interface (Communication Interface) 720, memory 730, and communication bus 740, wherein processor 710, communication interface 720, memory 730 communicate with each other via communication bus 740. Processor 710 may invoke a computer program in memory 730 to perform the steps of any of the mail encryption methods or any of the mail decryption methods provided by the embodiments described above, including, for example:

converting the mail ciphertext into a coding sequence by adopting a preset compression algorithm; style configuration is carried out on the plaintext of the mail based on a preset encryption comparison table and the coding sequence, and information of a copy person is generated; sending the mail plaintext to a mail receiver according to the information of the transcriber; or:

based on a pre-stored encryption comparison table, analyzing the information of the copy person of the mail and the text style information of the plaintext of the mail to obtain a coding sequence; and converting the coding sequence according to a pre-stored decompression algorithm to obtain a mail ciphertext.

Further, the logic instructions in the memory 730 described above may be implemented in the form of software functional units and may be stored in a computer readable storage medium when sold or used as a stand alone product. Based on such understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

In another aspect, embodiments of the present application further provide a computer program product, where the computer program product includes a computer program, where the computer program is capable of being stored on a non-transitory computer readable storage medium, where the computer program, when executed by a processor, is capable of performing the steps of any one of the mail encryption methods or any one of the mail decryption methods provided in the embodiments above, for example, including:

In another aspect, embodiments of the present application further provide a processor-readable storage medium storing a computer program for causing a processor to execute the steps of any one of the mail encryption methods or any one of the mail decryption methods provided in the above embodiments, for example, including:

The processor-readable storage medium may be any available medium or data storage device that can be accessed by a processor, including, but not limited to, magnetic storage (e.g., floppy disks, hard disks, magnetic tape, magneto-optical disks (MOs), etc.), optical storage (e.g., CD, DVD, BD, HVD, etc.), semiconductor storage (e.g., ROM, EPROM, EEPROM, nonvolatile storage (NAND FLASH), solid State Disk (SSD)), and the like.

The apparatus embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.

From the above description of the embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus necessary general hardware platforms, or of course may be implemented by means of hardware. Based on this understanding, the foregoing technical solution may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a computer readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the respective embodiments or some parts of the embodiments.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the corresponding technical solutions.

Claims

1. A mail encryption method, characterized by comprising:

2. The mail encryption method according to claim 1, wherein the encryption reference table includes a font style reference table, a transcriber address character table, and a transcriber domain name reference table; the style configuration of the mail plaintext based on the preset encryption comparison table and the coding sequence and the generation of the information of the copy person comprise the following steps:

3. The mail encryption method according to claim 2, wherein the generating the transcriber information based on the transcriber address character table, the transcriber domain name lookup table, and the second code sequence using the sequence other than the first code sequence as a second code sequence includes:

4. A mail encryption method according to claim 3, wherein the converting the second code sequence into a comparison parameter according to a preset conversion algorithm, extracting characters from the transcriber address character table according to the comparison parameter to form a transcriber prefix, extracting a transcriber domain name from the transcriber domain name comparison table, and generating the transcriber information according to the transcriber prefix and the transcriber domain name includes:

5. A mail decrypting method, characterized by comprising:

6. The mail decrypting method as claimed in claim 5, wherein the encryption reference table includes a font style reference table, a transcriber address character table and a transcriber domain name reference table, and the parsing the transcriber information of the mail and the text style information of the plaintext of the mail based on the pre-stored encryption reference table to obtain the coding sequence includes:

7. A mail encryption device, characterized by comprising:

8. A mail decrypting apparatus, characterized by comprising:

9. An electronic device comprising a processor and a memory storing a computer program, characterized in that the processor, when executing the computer program, implements the steps of the mail encryption method of any one of claims 1 to 4 or the steps of the mail decryption method of any one of claims 5 to 6.

10. A computer program product comprising a computer program, characterized in that the computer program, when being executed by a processor, implements the steps of the mail encryption method of any one of claims 1 to 4 or the mail decryption method of any one of claims 5 to 6.