Mail encryption method, decryption method and device
By introducing modality conversion during the email encryption process, the encrypted email is converted into different modalities and additional information is generated, which solves the problem of insufficient security caused by the single encryption method in the existing technology and achieves higher security and concealment.
Patent Information
- Application Number
- CN202411951881.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2026-06-30
AI Technical Summary
Existing email encryption technologies suffer from limited security due to their simplistic encryption methods, making encrypted messages easily identifiable and decipherable by attackers.
Introducing modality conversion during email encryption transforms part or all of the encrypted email into a different modality, such as converting text into audio, images, or video, and generates additional information to indicate the conversion rules and locations, thereby increasing encryption complexity.
By using modal switching, attackers' analysis of encrypted emails is disrupted, significantly improving the security and concealment of email transmission and increasing the difficulty of cracking.
Smart Images
Figure CN122316653A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of information and communication technology, and in particular relates to an email encryption method, decryption method and device. Background Technology
[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.
[0003] Traditional encryption technologies mainly include two types: symmetric encryption and asymmetric encryption. Symmetric encryption algorithms, such as DES and AES, use the same key for both encryption and decryption; asymmetric encryption algorithms, such as RSA and ECC, use both public and private keys for encryption and decryption. Both encryption technologies play a role in ensuring the security of email transmission.
[0004] Existing email encryption technologies offer a degree of security for email transmission, but they still have certain limitations. For example... Figure 1 As shown, existing email encryption technology typically encrypts the email content using existing encryption algorithms when the user sends the email, resulting in an encrypted email. However, because existing encryption methods are relatively simple, and the ciphertext in the email is usually in encoded form, it is easily recognized by attackers. Furthermore, by combining the encoding length and other patterns of the ciphertext, attackers can conduct targeted analysis and decryption, thus email security needs to be improved. Summary of the Invention
[0005] To overcome the shortcomings of the prior art, the present invention provides an email encryption method, decryption method and device, which introduces mode conversion into the email encryption process, increases the encryption complexity and improves the confidentiality and security of email information.
[0006] To achieve the above objectives, a first aspect of the present invention provides an email encryption method applied to a sending terminal, comprising the following steps:
[0007] In response to an email sending request, the plaintext of the email is encrypted to obtain the ciphertext of the email;
[0008] At least a portion of the encrypted email is converted into a different modality than the current modality; additional information is generated, including the encryption algorithm used, the position information of the at least portion before and after the modality conversion, and the modality conversion rules.
[0009] Send encrypted and modally converted email ciphertext, along with the additional information.
[0010] In some embodiments, at least a portion of the encrypted email is converted into another modality different from the current modality, specifically by generating other modal data based on the at least a portion, or by hiding the at least a portion within the data of another modality.
[0011] In some embodiments, the data of the other modalities is data in the current email, or pre-stored data of other modalities.
[0012] A second aspect of the present invention provides an email encryption method applied to a sending terminal, comprising the following steps:
[0013] In response to an email sending request, the plaintext of the email is segmented, and each segment is encrypted to obtain multiple encrypted email segments.
[0014] At least one of the multiple encrypted email segments is converted to a different modality than the current modality; the additional information includes the position information of each segment before and after encryption, the encryption algorithm used, whether modality conversion was performed, and the modality conversion rules;
[0015] The multiple encrypted email segments are merged and sent, along with the additional information.
[0016] In some embodiments, the additional information is encrypted based on a shared key between the sender and receiver terminals before being sent.
[0017] A third aspect of the present invention provides an email decryption method applied to a receiving terminal, comprising the following steps:
[0018] Obtain the ciphertext and additional information of the email generated by the sending terminal based on the email encryption method;
[0019] Based on the additional information, the location of the ciphertext portion that has undergone modality transformation, as well as the modality transformation rules, are obtained through parsing.
[0020] According to the modality conversion rules, the ciphertext portion that has undergone modality conversion is converted back to the original modality to obtain the ciphertext in the original modality.
[0021] Based on the additional information, the encryption algorithm used is parsed, and the ciphertext in the original mode is decrypted to obtain the plaintext of the email.
[0022] A fourth aspect of the present invention provides an email decryption method applied to a receiving terminal, comprising the following steps:
[0023] Obtain the ciphertext and additional information of the email generated by the sending terminal based on the email encryption method;
[0024] Based on the additional information, the position of each segment in the ciphertext is parsed, as well as whether each segment has undergone modality transformation and the modality transformation rules used for segments that have undergone modality transformation.
[0025] According to the modality conversion rules, the segments that have undergone modality conversion are converted into the original modality, and the ciphertext of each segment in the original modality is obtained;
[0026] Based on the additional information, the encryption algorithm used for each segment is parsed, the ciphertext of each segment in the original mode is decrypted, and the segments are combined according to their order in the plaintext of the email to obtain the plaintext of the email.
[0027] In some embodiments, after obtaining the additional information, the additional information is also decrypted based on a shared key between the sender terminal and the sender terminal.
[0028] A fifth aspect of the present invention provides a communication device, the communication device including one or more processors; and a memory; wherein the memory stores one or more computer programs, the one or more computer programs including instructions that, when executed by the communication device, cause the communication device to perform the method.
[0029] A sixth aspect of the present invention provides a computer-readable storage medium storing instructions that, when executed on a communication device, cause the communication device to perform the method.
[0030] In one or more of the above technical solutions, in addition to conventional encryption of plaintext emails, a modality conversion approach is introduced to convert at least part of it into other modalities different from the current modality. This achieves diversified hiding of email content, greatly interferes with attackers' analysis of encrypted emails, increases the difficulty of cracking, and thus greatly improves the security and concealment of email transmission. Attached Figure Description
[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0032] Figure 1 This is a schematic diagram of the email encryption process in existing technologies;
[0033] Figure 2 This is a flowchart of an email encryption method according to an embodiment of the present invention;
[0034] Figure 3 This is a flowchart of another email encryption method in an embodiment of the present invention;
[0035] Figure 4 This is a flowchart of an email decryption method according to an embodiment of the present invention;
[0036] Figure 5 This is a flowchart of another email decryption method in an embodiment of the present invention;
[0037] Figure 6 This is a schematic diagram of the email sending and receiving process based on the email encryption and decryption methods in this embodiment of the invention. Detailed Implementation
[0038] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0039] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0040] In one or more of the following embodiments, the sending terminal and receiving terminal may be personal computers, mobile phones (also known as cell phones), tablet computers, televisions (also known as smart screens or large-screen devices), ultra-mobile personal computers (UMPCs), handheld computers, netbooks, personal digital assistants (PDAs), in-vehicle devices (also known as vehicle systems), wearable electronic devices, virtual reality devices, etc. The embodiments of this application do not impose any limitations on them.
[0041] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.
[0042] As described in the background section, existing email encryption methods are relatively simple, making it easy for attackers to analyze the length and encoding characteristics of ciphertext and thus crack the encryption algorithm. Therefore, one or more embodiments of this invention provide a novel email encryption method that, in addition to traditional encryption of email content, performs modal transformation, converting at least a portion of the email content into a different modality, such as converting text to images, audio, or video, achieving cross-media hybrid encryption and effectively improving the security and practicality of email encryption.
[0043] Figure 2 A flowchart of an email encryption method is shown, including steps S201-S203. The method includes the following steps:
[0044] S201: In response to the email sending request, encrypt the plaintext of the email to obtain the ciphertext of the email;
[0045] S202: Convert at least a portion of the encrypted email into a different modality than the current modality; simultaneously generate additional information, including the encryption algorithm used, the position information of the at least a portion before and after the modality conversion, and the modality conversion rules;
[0046] S203: Send the encrypted and modally converted email ciphertext, along with the additional information.
[0047] After the plaintext of the email is encrypted in a conventional way, at least a portion of it is modally converted. For example, the media format of the plaintext portion of the email that is modally converted is text, and the converted media format can be at least one of audio, image, and video, but it can no longer be text. This achieves diversified hiding of the email content, greatly interferes with the attacker's analysis of the encrypted email, increases the difficulty of cracking it, and thus greatly improves the security and concealment of email transmission.
[0048] In step S201, encrypting the plaintext email can be achieved using any existing encryption algorithm. As an example, both the sending and receiving terminals have multiple pre-configured encryption algorithms for each modality of data, thus enabling encryption of any modality of data in the plaintext email. For example, for text data, encryption algorithms such as AES and RSA are pre-configured. When encrypting the plaintext email, encryption is performed based on an algorithm selected by the user from the multiple encryption algorithms, or by an algorithm randomly selected from the multiple encryption algorithms, resulting in ciphertext email.
[0049] When the plaintext of an email contains data in multiple modalities, the appropriate encryption algorithm is selected for each modality. This step does not change the data's modality.
[0050] In step S202, at least a portion of the encrypted email is converted into another modality different from the current modality to generate other modal data based on the at least a portion, or the at least a portion is hidden within the data of another modality. For the second approach, the data of other modalities can be obtained from the content of the email itself or from a pre-stored multimodal database. For example, if the email itself contains multimodal data, such as text and images, then after encrypting both the text and images, the encrypted text can be further embedded into the encrypted images, achieving cross-modal and diverse encryption and increasing the difficulty of cracking.
[0051] The additional information serves as a description of the email encryption process, used by the recipient to decrypt the email after receiving it. The additional information includes the encryption algorithm used, the position information of at least part of the ciphertext before and after modality conversion, and the modality conversion rules. The encryption algorithm used is the same as the one employed in step S201; the position information of at least part of the ciphertext before and after modality conversion indicates the position of the ciphertext in the plaintext after decryption, and indicates which part of the ciphertext underwent modality conversion, which can be represented by byte positions or other methods; the modality conversion rules record the algorithm and rules used to convert the modality from the original modality to the current modality, facilitating the recipient's conversion back to the original modality.
[0052] To convert ciphertext from a text modality into an audio modality, the encrypted information can be embedded into a given audio file using methods such as frequency modulation and phase coding. As an example, the ciphertext is first encoded (e.g., ASCII or Unicode) and converted into a binary data sequence. Then, the carrier signal of the given audio is modulated based on a preset modulation scheme (e.g., BPSK or QAM), thus hiding the ciphertext from the text modality within the audio file.
[0053] The given audio can be audio from an email or pre-stored audio. In this case, the modality conversion rules in the additional information must include the embedding position of the ciphertext in the audio file, the modulation method used, and the encoding method of the ciphertext.
[0054] To convert ciphertext from a text modality to an image modality, the ciphertext can be embedded into the pixel values, color channels, or metadata of an image file, or hidden in the frequency domain, achieving covert transmission of information. As an example of hiding by modifying pixel values, the ciphertext is first encoded (e.g., ASCII or Unicode) and converted into a binary data sequence with a length less than or equal to the number of pixels in the image. Then, the pixels of the given image are traversed, and for each pixel's color channel, the least significant bit of the binary representation of its corresponding channel value is replaced with the corresponding bit in the ciphertext binary sequence, thus completing the embedding of all ciphertext. As an example of hiding in the frequency domain, the ciphertext is first encoded (e.g., ASCII or Unicode) and converted into a binary data sequence. Then, the given image is transformed from the spatial domain to the DCT or wavelet domain, and the binary data sequence is embedded into the transform domain coefficients of the image according to certain rules. Finally, an inverse transform is performed on the image to obtain the image with the embedded text.
[0055] The given image can be an image in an email or a pre-stored image. If the ciphertext is hidden by modifying pixel values, the modal conversion rules in the additional information must include the embedding rules of the ciphertext in the image and the encoding method of the ciphertext. If the ciphertext is hidden by hiding it in the frequency domain, the modal conversion rules in the additional information must include the image transformation algorithm used, the embedding rules of the ciphertext in the transform domain coefficients, and the encoding method of the ciphertext.
[0056] To convert ciphertext from a text modality to a video modality, similar to embedding images, video files offer more embedding space. The ciphertext can be hidden by modifying specific portions of the video frames or adding invisible layers. As an example of hiding via video frame modification, the ciphertext is first encoded (e.g., ASCII or Unicode) and converted into a binary data sequence. One or more video frame images are extracted from the given video based on the length of the binary data sequence, such that the length of the binary data sequence is less than or equal to the total number of pixels in the one or more video frame images. The pixels of each video frame image are then iterated through sequentially, and for each pixel's color channel, the least significant bit of the binary representation of its corresponding channel value is replaced with the corresponding bit from the ciphertext binary sequence, thus completing the embedding of all ciphertext. As an example of adding invisible layers, the ciphertext is encoded according to certain rules into values suitable for embedding in the alpha channel (range 0 to 255), and these values are then filled into the alpha channel of the video frames.
[0057] The given video can be a video in an email or a pre-stored video. If the ciphertext is hidden by modifying video frames, the modality conversion rules in the additional information must include the position information of the video frame image in the given video, the embedding rules of the ciphertext in the image, and the encoding method of the ciphertext. If the ciphertext is hidden by adding an invisible layer, the modality conversion rules in the additional information must include the position information of the video frame image in the given video, the embedding rules of the ciphertext in the alpha channel, and the encoding method of the ciphertext.
[0058] To convert ciphertext from an audio modality to a text modality, the encrypted audio is first converted into a binary data sequence. This binary data sequence is then converted into an ASCII character sequence using Base64 encoding. The ASCII character sequence is then embedded into a given text according to predefined rules. This given text can be text from an email or pre-stored text. The modality conversion rules in the additional information must include the embedding rules for the character sequence in the given text, the character encoding method, and the algorithm for converting the audio to binary data.
[0059] To convert ciphertext from an audio modality to an image modality, the encrypted audio must first be converted into a binary data sequence. Then, the same method used to convert text modality to an image modality can be employed. In this case, the modality conversion rules in the additional information must also include an algorithm for converting audio to binary data.
[0060] To convert ciphertext from an audio modality to a video modality, the encrypted audio must first be converted into a binary data sequence. Then, the same method used to convert text modality to video modality can be employed. In this case, the modality conversion rules in the additional information must also include an algorithm for converting audio to binary data.
[0061] To convert the encrypted image modality into a text modality, the encrypted image is first converted into a binary data sequence. This binary data sequence is then converted into an ASCII character sequence using Base64 encoding. The ASCII character sequence is then embedded into a given text according to predefined rules. This given text can be text from an email or pre-stored text. The modality conversion rules in the additional information must include the embedding rules for the character sequence in the given text, the character encoding method, and the algorithm for converting the image into binary data.
[0062] To convert the encrypted image modality to the audio modality, the encrypted image is first converted into a binary data sequence; then, the same method as converting the text modality to the audio modality can be used. In this case, the modality conversion rules in the additional information also need to include an algorithm for converting the image to binary data.
[0063] To convert ciphertext from an image modality to a video modality, the encrypted image is first converted into a binary data sequence; then, the same method as converting text modality to video modality can be used. In this case, the modality conversion rules in the additional information must also include an algorithm for converting the image to binary data.
[0064] To convert ciphertext from a video modal to text modal, first extract the video frame images frame by frame from the encrypted video; then, the same method as converting ciphertext from an image modal to text modal can be used.
[0065] To convert ciphertext from a video modal to an audio modal, the encrypted video is first extracted frame by frame and converted into a binary data sequence. Then, the same method used to convert text modal to audio modal can be employed. In this case, the modal conversion rules in the additional information must also include an algorithm for converting video to binary data.
[0066] To convert the encrypted video modality to the image modality, the encrypted video is first extracted frame by frame and converted into a binary data sequence. Then, the same method used to convert the text modality to the image modality can be applied. In this case, the modality conversion rules in the additional information also need to include an algorithm for converting the video to binary data.
[0067] In one or more of the above embodiments, after the plaintext email is conventionally encrypted, at least a portion of the ciphertext is modally converted. This modal conversion can be a direct conversion of the at least a portion of the ciphertext into other modalities, or it can be hidden within other modalities. Furthermore, when hiding the ciphertext within other modalities, data from other modalities can be extracted from the email itself as the embedding basis, or pre-stored data from other modalities can be selected as the embedding basis. The encrypted email content exists in the form of a seemingly ordinary media file, making it difficult to attract the attention of attackers and enhancing the stealth during transmission, greatly increasing the difficulty of cracking the email. By providing diverse encryption and conversion methods, users can choose encryption algorithms and conversion methods according to their actual needs, thereby flexibly responding to different security threats and transmission environments.
[0068] Furthermore, if data from other modalities is extracted from this email as the basis for embedding, since the data from those other modalities has already been encrypted in S201, converting and embedding the information from those other modalities further increases the difficulty of cracking.
[0069] As a more specific implementation of the above method, such as Figure 3 As shown, the email encryption method includes the following steps:
[0070] S301: In response to an email sending request, the plaintext of the email is segmented and encrypted to obtain multiple ciphertext segments;
[0071] S302: Convert at least one of the plurality of encrypted email segments into a different mode than the current mode; at the same time generate additional information, the additional information including the position information of each segment before and after encryption, the encryption algorithm used, whether mode conversion was performed, and the mode conversion rules;
[0072] S303: Merge the multiple encrypted email segments and send them, while also sending the additional information.
[0073] In step S301, the plaintext email can be single-modal data or multi-modal data, and the multi-modal information includes at least two of text, images, audio, and video. If the plaintext email is single-modal data, such as text data, it can be segmented with a set character length as the interval or with punctuation marks as the interval; no specific limitation is made here. The encryption algorithms used to encrypt each segment of the plaintext email can be the same or different. If the plaintext email includes multi-modal data, each modality of data can be considered as a segment.
[0074] For specific encryption methods, please refer to the relevant explanation in step S201. Understandably, the encryption algorithms used in each segment can be the same or different.
[0075] In step S302, depending on the encryption level, one or more of the encrypted email segments can be modally converted. Understandably, the more segments and the more modal conversions performed, the higher the encryption level. At the highest encryption level, each encrypted email segment can be converted to a different modality than the current one.
[0076] The additional information serves as a description of the email encryption process, used by the recipient to decrypt the email after receiving it. This additional information includes the position information of each segment before and after encryption, the encryption algorithm used, whether modality conversion was performed, and the modality conversion rules. Specifically, the position information of each segment before encryption indicates its position in the plaintext of the email and can be represented using a sequential index; the position information of each segment after encryption indicates its position in the ciphertext; the encryption algorithm used is the same as the encryption algorithm used for that segment; whether modality conversion was performed can be represented by 0 or 1; if modality conversion was performed, the segment also has modality conversion rules.
[0077] Depending on the mode type before and after the mode transition, the mode transition rules will differ. Please refer to the relevant explanation in step S202 for details.
[0078] In step S303, it is understood that when merging the multiple encrypted email segments, they can be merged in any order, and the recipient can restore the order based on the position of the segments in the additional information.
[0079] By flexibly segmenting email content, different encryption algorithms can be applied to each segment, and modality conversion can be selectively performed to achieve a higher level of cross-media hybrid encryption. Compared to plaintext emails, ciphertext emails can include more modalities. For example, while the original plaintext email contains only text, the ciphertext includes images, audio, and video, increasing the complexity and security of encryption. This avoids the vulnerability of using a single encryption method or algorithm to targeted analysis by attackers, effectively improving the security and practicality of email encryption.
[0080] To further enhance security, the sending terminal and the receiving terminal also pre-store a shared key, or apply for a temporary service key when establishing a communication connection, which is used to encrypt the additional information in step S203 or step S303.
[0081] After the email is sent using the encryption method described above, the ciphertext and additional information are sent to the recipient via email. The additional information is encrypted before being transmitted to the recipient. The recipient then parses the received media file based on the decrypted additional information to obtain the ciphertext of the email. The recipient then uses the same decryption algorithm as the sender to decrypt the ciphertext, obtaining the plaintext email. Figure 4 This diagram illustrates the overall flowchart of an email decryption method applied to email recipients, specifically including the following steps:
[0082] S401: Retrieve encrypted email content and additional information;
[0083] S402: Based on the additional information, the location of the ciphertext portion that has undergone modality conversion, and the modality conversion rules are parsed out;
[0084] S403: According to the modality conversion rule, the ciphertext portion that has undergone modality conversion is converted into the original modality to obtain the ciphertext in the original modality;
[0085] S404: Based on the additional information, the encryption algorithm used is parsed, and the ciphertext in the original mode is decrypted to obtain the plaintext of the email.
[0086] Understandably, if the email encryption process is segmented based on steps S301-S303, then, accordingly, Figure 5 As shown, the email decryption method specifically includes the following steps:
[0087] S501: Retrieve encrypted email content and additional information;
[0088] S502: Based on the additional information, parse the position of each segment in the ciphertext, whether each segment has undergone modality transformation, and the modality transformation rules used for segments that have undergone modality transformation;
[0089] S503: According to the modality conversion rule, the segments that have undergone modality conversion are converted into the original modality to obtain the ciphertext of each segment in the original modality;
[0090] S504: Based on the additional information, the encryption algorithm used for each segment is parsed, the ciphertext of each segment in the original mode is decrypted, and the segments are combined according to their order in the plaintext of the email to obtain the plaintext of the email.
[0091] Understandably, if the additional information is encrypted in step S203 or step S303, then the additional information obtained in step S401 or S501 is encrypted. The additional information is first decrypted to obtain the additional information before subsequent operations are performed.
[0092] Figure 6 The diagram illustrates the process of encryption and decryption based on the above methods. The sending terminal divides the plaintext text of the email into three segments, then converts each segment into a different modality before sending it. Upon receiving the encrypted email, the receiving terminal first converts each segment into ciphertext segments of the original modality according to the modality conversion rules in the attachment information. These ciphertext segments are then decrypted to obtain the plaintext segments, which are then combined sequentially to obtain the original plaintext. Based on this method, in the undecrypted state, the user can normally see the images, audio, and video converted from the ciphertext. Only after modality conversion and decryption can the plaintext be obtained, enhancing the confidentiality of the email content. Furthermore, the increased encryption complexity and flexibility significantly increase the difficulty of deciphering the ciphertext, thereby improving the security of email transmission.
[0093] One or more embodiments of the present invention also provide a communication device that can be used to implement the methods executed in the sending terminal and receiving terminal of the above embodiments. The communication device includes one or more processors, one or more memories coupled to the processors, and a communication module coupled to the processors.
[0094] The memory may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, at least one of the following: read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, hard disk, compact disc (CD), digital video disc (DVD), or other magnetic and / or optical storage. Examples of volatile memories include, but are not limited to, at least one of the following: random access memory (RAM), or other volatile memories that do not persist during power-off periods. The computer program may be stored in the ROM. When the processor executes the computer program, it implements any of the above methods.
[0095] In some embodiments, the program may be tangibly contained in a computer-readable storage medium, which may include in a device (such as in memory) or other storage device accessible by the device. The program may be loaded from the computer-readable storage medium into RAM for execution. The computer-readable storage medium may include any type of tangible non-volatile memory, such as ROM, EPROM, flash memory, or hard disk, storing a computer program that, when executed by a processor, implements any of the methods described above.
[0096] Various embodiments of the present invention can be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects can be implemented in hardware, while others can be implemented in firmware or software, which can be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of this disclosure are shown and described as block diagrams, flowcharts, or represented using some other illustration, it should be understood that the blocks, apparatuses, systems, techniques, or methods described herein can be implemented as, as non-limiting examples, in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.
[0097] Although the operation of the method of the present invention is described in a specific order in the accompanying drawings, this does not require or imply that the operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Rather, the steps depicted in the flowcharts may be performed in a different order. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps. It should also be noted that the features and functions of two or more devices according to this disclosure may be embodied in one device. Conversely, the features and functions of one device described above may be further divided and embodied by multiple devices.
Claims
1. An email encryption method, applied to a sending terminal, characterized in that, Includes the following steps: In response to an email sending request, the plaintext of the email is encrypted to obtain the ciphertext of the email; At least a portion of the encrypted email is converted into a different modality than the current modality; additional information is generated, including the encryption algorithm used, the position information of the at least portion before and after the modality conversion, and the modality conversion rules. Send encrypted and modally converted email ciphertext, along with the additional information.
2. The email encryption method as described in claim 1, characterized in that, Converting at least a portion of the encrypted email into a different modality from the current modality specifically involves: generating other modal data based on the at least a portion, or hiding the at least a portion within the data of other modalities.
3. The email encryption method as described in claim 2, characterized in that, The data in the other modalities refers to the data in the current email or other pre-stored modal data.
4. An email encryption method, applied to a sending terminal, characterized in that, Includes the following steps: In response to an email sending request, the plaintext of the email is segmented, and each segment is encrypted to obtain multiple encrypted email segments. Convert at least one of the plurality of encrypted email segments into a different modality than the current modality; The additional information includes the position information of each segment before and after encryption, the encryption algorithm used, whether mode conversion was performed, and the mode conversion rules; The multiple encrypted email segments are merged and sent, along with the additional information.
5. The email encryption method according to any one of claims 1-4, characterized in that, Before sending the additional information, the additional information is also encrypted based on a shared key between the sender and receiver terminals.
6. An email decryption method, applied to a receiving terminal, characterized in that, Includes the following steps: Obtain the ciphertext and additional information of the email generated by the sending terminal based on the email encryption method as described in any one of claims 1-3 and 5; Based on the additional information, the location of the ciphertext portion that has undergone modality transformation, as well as the modality transformation rules, are obtained through parsing. According to the modality conversion rules, the ciphertext portion that has undergone modality conversion is converted back to the original modality to obtain the ciphertext in the original modality. Based on the additional information, the encryption algorithm used is parsed, and the ciphertext in the original mode is decrypted to obtain the plaintext of the email.
7. An email decryption method, applied to a receiving terminal, characterized in that, Includes the following steps: Obtain the ciphertext and additional information of the email generated by the sending terminal based on the email encryption method as described in claim 4 or 5; Based on the additional information, the position of each segment in the ciphertext is parsed, as well as whether each segment has undergone modality transformation and the modality transformation rules used for segments that have undergone modality transformation. According to the modality conversion rules, the segments that have undergone modality conversion are converted into the original modality, and the ciphertext of each segment in the original modality is obtained; Based on the additional information, the encryption algorithm used for each segment is parsed, the ciphertext of each segment in the original mode is decrypted, and the segments are combined according to their order in the plaintext of the email to obtain the plaintext of the email.
8. A method for decrypting emails as described in claim 6 or 7, characterized in that, After obtaining the additional information, the additional information is also decrypted based on the shared key between the sender terminal and the sender terminal.
9. A communication device, the communication device comprising one or more processors; and a memory; wherein, The memory stores one or more computer programs, the one or more computer programs including instructions, characterized in that, when the instructions are executed by the communication device, the communication device performs the method according to any one of claims 1-8.
10. A computer-readable storage medium storing instructions, characterized in that, When the instructions are executed on the communication device, the communication device performs the method according to any one of claims 1-8.