Encryption Method for 3D Printing Model Slicing Files, Decryption Printing Method and 3D Printing Device

Abstract

The encryption method of the present invention first compresses and performs primary encryption on the layer data generated by slicing the 3D model; then randomly extracts discontinuous layer data from the encryption parameter area and each layer of data for secondary encryption; then performs SHA-256 operation and secondary encryption on the encryption parameter area, preview image, and layer data to obtain the SHA-256 encryption signature and splice it at the end of the file to form an overall signature encrypted file; in its decryption method, after the control unit reads the signature encrypted file, it judges whether the firmware of the control unit and each compatibility information in the signature encrypted file match; then performs secondary decryption on the SHA-256 encryption signature to obtain the string M1; then performs SHA-256 operation on the encryption parameter area, preview image, and layer data in the signature encrypted file to obtain the string M2; if the strings M1 and M2 are the same, decrypt the parameter area and set the printing parameters, then perform secondary decryption, primary decryption, and decompression on the layer data to obtain the plaintext of the layer data, and finally perform layer-by-layer exposure printing.

Description

Technical Field

[0001] This application relates to the field of 3D printing technology, and particularly to an encryption method for 3D printing model slice files, a decryption and printing method, and a 3D printing device. Background Art

[0002] Currently, with the rapid development of 3D printing technology, with the wide application of 3D printers in the manufacturing industry and competition in the consumer market, users increasingly attach importance to the confidentiality of original design files. Therefore, there are increasingly high requirements for the data security and confidentiality of design files in the 3D printing process. Moreover, in the data distribution and sample printing and trial use links of some figurine or industrial model design enterprises, in order to further strengthen the protection of their original works, they will also require serial number authorization for specified 3D printers to make them authorized printing terminals to achieve limited printing under intellectual property authorization. Therefore, it is necessary to encrypt the slice files generated in the 3D printing preprocessing slicing link to generate slice encrypted files with higher security. At the same time, the corresponding 3D printer needs to be able to decrypt, identify, read, and execute printing of the encrypted content in the slice encrypted files.

[0003] In addition, in order to prevent the encrypted slice files from being modified or forcibly cracked, it is necessary to perform SHA-256 algorithm verification on them to ensure the correctness and integrity of the encrypted slice files.

[0004] Furthermore, the original data volume of the slice files generated in the 3D printing preprocessing slicing link is huge and requires a large amount of storage space. Therefore, it is necessary to compress the data to save storage space and further encrypt the slice files on the basis of compression.

[0005] Therefore, in order to comprehensively meet the above requirements, it is necessary to provide an encryption method for 3D printing model slice files, a decryption and printing method, and a 3D printing device. Summary of the Invention

[0006] To meet the requirements in the above-mentioned background technology, the present invention provides an encryption method for 3D printing model slice files; provides a decryption and printing method for 3D printing model slice files; provides two 3D printing devices applying the decryption and printing method. In the encryption method, first, compress and perform primary encryption on the layer data generated from the 3D model slices; then randomly extract discontinuous layer data from the encrypted parameter area and each layer of data for secondary encryption; then perform SHA-256 operation and secondary encryption on the encrypted parameter area, preview image, and layer data to obtain a SHA-256 encrypted signature and splice it at the end of the file to form an overall signature encrypted file; in the decryption method, after the control unit reads the signature encrypted file, determine whether the firmware of the control unit and each compatibility information in the signature encrypted file match; then perform secondary decryption on the SHA-256 encrypted signature to obtain a string M1; then perform SHA-256 operation on the encrypted parameter area, preview image, and layer data in the signature encrypted file to obtain a string M2; if the strings M1 and M2 are the same, decrypt the parameter area and set the printing parameters, then perform secondary decryption, primary decryption, and decompression on the layer data to obtain the plaintext of the layer data, and finally perform layer-by-layer exposure printing. The technical methods adopted by the present invention are as follows:

[0007] Method 1, an encryption method for 3D printing model slice files, which includes the following steps:

[0008] S01. The user performs slicing processing and saves a 3D model through 3D slicing software to obtain a first slice file with multiple layers of data;

[0009] S02. The 3D slicing software compresses and encodes the multiple layers of data in the first slice file to obtain a second slice file with multiple compressed layers of data;

[0010] S03. The 3D slicing software performs primary encryption on the multiple compressed layers of data in the second slice file to obtain a third slice file with multiple primary encrypted compressed layers of data;

[0011] S04. The 3D slicing software performs secondary encryption on the parameter area of the third slice file to obtain a fourth slice file;

[0012] S05. The 3D slicing software randomly extracts discontinuous X layers from the primary encrypted compressed layer data in the fourth slice file for secondary encryption to obtain a fifth slice file;

[0013] S06. The 3D slicing software performs SHA-256 operation on the part other than the recognized file header in the fifth slice file and performs secondary encryption on the operation result to obtain a SHA-256 encrypted signature;

[0014] S07. The 3D slicing software splices the SHA-256 encrypted signature at the end of the fifth slice file to form an overall signature encrypted file;

[0015] S08. The 3D slicing software completes the final storage and renaming of the signed and encrypted file at the specified storage path;

[0016] S09. The process ends.

[0017] Further, the first slice file includes: a file header, a preview image, and layer slice data; wherein, the file header further includes: an identification file header and a parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction orders and their corresponding layer data; wherein, each layer data header is an index of its corresponding layer data;

[0018] The second slice file includes: a file header, a preview image, and layer slice data; wherein, the file header further includes: an identification file header and a parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction orders and their corresponding compressed layer data; wherein, each layer data header is an index of its corresponding compressed layer data;

[0019] The third slice file includes: a file header, a preview image, and layer slice data; wherein, the file header further includes: an identification file header and a parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction orders and their corresponding first-level encrypted and compressed layer data; wherein, each layer data header is an index of its corresponding first-level encrypted and compressed layer data;

[0020] The fourth slice file includes: a file header, a preview image, and layer slice data; wherein, the file header further includes: an identification file header and a second-level encryption parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction orders and their corresponding first-level encrypted and compressed layer data; wherein, each layer data header is an index of its corresponding first-level encrypted and compressed layer data;

[0021] The fifth slice file includes: a file header, a preview image, and layer slice data; wherein, the file header further includes: an identification file header and a second-level encryption parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction orders and their corresponding first-level encrypted and compressed layer data, and a plurality of layer data headers with intermittent construction orders and their corresponding second-level encrypted and compressed layer data; wherein, each layer data header is an index of its corresponding first-level encrypted and compressed layer data or second-level encrypted and compressed layer data;

[0022] The signed and encrypted file includes: a file header, a preview image, layer slice data, and a SHA-256 encrypted signature; wherein, the file header further includes: an identification file header and a secondary encryption parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of sequentially consecutive layer data headers and their corresponding first-level encrypted and compressed layer data, and a plurality of layer data headers with sequential intervals and their corresponding second-level encrypted and compressed layer data; wherein, each layer data header is an index for its corresponding first-level encrypted and compressed layer data or second-level encrypted and compressed layer data; the contents of the three parts of the secondary encryption parameter area, the preview image, and the layer slice data are subjected to SHA-256 operation, and then the operation result is secondarily encrypted to obtain the SHA-256 encrypted signature; the SHA-256 encrypted signature is concatenated at the end of the fifth slice file.

[0023] Preferably, the method adopted for the first-level encryption includes: a substitution cipher algorithm or a shift cipher algorithm; the methods adopted for the second-level encryption include: an AES encryption algorithm, an RSA encryption algorithm, a DES encryption algorithm, or an ECC encryption algorithm.

[0024] Preferably, when the 3D slicing software randomly extracts non-consecutive X layers from the first-level encrypted and compressed layer data in the fourth slice file for secondary encryption, the number of layers of the randomly extracted X layers is concentrated within the range of 11% - 89% of the total layer order;

[0025] Preferably, the value of X is a specified positive integer.

[0026] Preferably, when the 3D slicing software compresses and encodes the multiple layer data of the first slice file to obtain a second slice file with multiple compressed layer data, the rules for compressing and encoding the layer data include: storing the repeated single digits in the continuous data segment into the highest bit of the compressed data segment, and storing the count value into the lower 7 bits of the compressed data segment; or, storing the repeated single digits in the continuous data segment into the lowest bit of the compressed data segment, and storing the count value into the higher 7 bits of the compressed data segment; wherein, the continuous data segment is a data segment composed of continuous single digits, and the compressed data segment includes the value of the single digit and the number of repetitions.

[0027] Method 2, a decryption and printing method for 3D printing model slice files, which includes the following steps:

[0028] SS01. The user imports the signed and encrypted file into the storage unit of the stereolithography printing device;

[0029] SS02. The control unit reads the signed and encrypted file in the storage unit;

[0030] SS03. The control unit determines whether the magic number in its firmware matches the magic number in the identification file header within the signature-encrypted file; if it is determined that the magic number in the control unit's firmware does not match the magic number in the identification file header within the signature-encrypted file, then step SS16 is performed; if it is determined that the magic number in the control unit's firmware matches the magic number in the identification file header within the signature-encrypted file, then step SS04 is performed;

[0031] SS04. The control unit determines whether the slice format version list in its firmware supports the slice format version in the identification file header within the signature-encrypted file; if it is determined that the slice format version list in the control unit's firmware does not support the slice format version in the identification file header within the signature-encrypted file, then step SS16 is performed; if it is determined that the slice format version list in the control unit's firmware supports the slice format version in the identification file header within the signature-encrypted file, then step SS05 is performed;

[0032] SS05. The control unit determines whether the OS version number in its firmware matches the OS version number in the identification file header within the signature-encrypted file; if it is determined that the OS version number in the control unit's firmware does not match the OS version number in the identification file header within the signature-encrypted file, then step SS16 is performed; if it is determined that the OS version number in the control unit's firmware matches the OS version number in the identification file header within the signature-encrypted file, then step SS06 is performed;

[0033] SS06. The control unit performs a secondary decryption on the SHA-256 encrypted signature in the signature-encrypted file to obtain the string M1;

[0034] SS07. The control unit performs a SHA-256 operation on the part other than the identification file header and the signature in the signature-encrypted file to obtain the string M2;

[0035] SS08. The control unit determines whether the strings M1 and M2 are the same; if it is determined that the strings M1 and M2 are different, then step SS16 is performed; if it is determined that the strings M1 and M2 are the same, then step SS09 is performed;

[0036] SS09. The control unit performs a secondary decryption on the parameters in the secondary encryption parameter area and correspondingly sets the plaintext of each decrypted parameter as the print execution parameter of the control unit;

[0037] SS10. The control unit sequentially reads the slice data of the Nth layer;

[0038] SS11. The control unit determines whether the read layer slice data is secondarily encrypted; if it is determined that the read layer slice data is not secondarily encrypted, then step SS13 is performed; if it is determined that the read layer slice data has been secondarily encrypted, then step SS12 is performed;

[0039] SS12. The control unit performs secondary decryption on the read layer slice data;

[0040] SS13. The control unit first performs primary decryption and decompression on the read layer slice data, and then exposes and prints the plaintext of the obtained layer slice data;

[0041] SS14. The control unit determines whether all layer slice data has been completely exposed and printed; if it is determined that all layer slice data has been completely exposed and printed, proceed to step SS17; if it is determined that not all layer slice data has been completely exposed and printed, proceed to step SS15;

[0042] SS15. The control unit sequentially reads the (N + 1)-th layer slice data, and the next step is to proceed to step SS11;

[0043] SS16. The control unit sends out an error signal and exits the program;

[0044] SS17. The process ends.

[0045] Preferably, between the steps SS03, SS04, SS05 and their respective step contents, there are also multiple combined corresponding relationships generated by swapping the step contents in a permutation and combination manner.

[0046] Preferably, the method adopted for the primary decryption includes: substitution cipher algorithm, or shift cipher algorithm; the methods adopted for the secondary decryption include: AES encryption algorithm, or RSA encryption algorithm, or DES encryption algorithm, or ECC encryption algorithm; N is a positive integer starting from 1 and increasing.

[0047] The 3D printing device 1 that decrypts using the above method 2 includes: a control unit, an LCD screen, a motor, a storage unit, a UVLED light source module, a display and operation unit, a forming platform, a liquid tank, a lifting column, a bottom film, photosensitive resin, and a base;

[0048] The control unit, LCD screen, UVLED light source module, and liquid tank are connected to the base; the motor is connected to the forming platform; the lifting column is fixedly connected to the base; the motor is installed on the lifting column to achieve electric drive lifting and drive the forming platform to lift or lower with it; the bottom film is arranged at the bottom of the liquid tank for light transmission; the liquid tank contains photosensitive resin liquid; the control unit is electrically connected to the LCD screen, motor, storage unit, UVLED light source module, display and operation unit; the storage unit stores the signature encrypted file; the control unit reads the signature encrypted file in the storage unit; the control unit performs SHA-256 verification, secondary decryption, primary decryption, and decompression on the signature encrypted file to obtain the plaintext of the printing parameters and the plaintext of the layer data. The control unit sets the plaintext of the printing parameters as the printing execution parameters and performs mask exposure layer by layer on the plaintext of the layer data; the control unit controls the motor to drive the forming platform to perform lifting movement according to the printing execution parameters; the user issues an operation instruction to the control unit through the display and operation unit, so that the control unit responds to the instruction and issues a control signal to control each controlled unit to complete the instruction action to achieve human-computer interaction operation; the control unit outputs signals and data to the display and operation unit to display the 3D model slice mask preview image, printing movement execution parameters, mask image exposure time parameters, system setting options, and system operation parameters; the control unit controls the motor to drive the forming platform to perform lifting movement according to the plaintext of the printing parameters; the control unit controls the UVLED light source module to turn on or off; the UVLED light source module emits ultraviolet light and visible light to expose and irradiate the photosensitive resin in the liquid tank through the mask image and the bottom film in the LCD screen to cure and form; the forming platform is used to attach the cured model resin layer during the curing and forming process to continuously lift and grow until 3D printing is completed; the 3D printing device adopts an upward LCD light-curing 3D printer or a downward LCD light-curing 3D printer.

[0049] The 3D printing device 2 decrypted by using the above method 2 includes: a control unit, a projection device, a motor, a storage unit, a display and operation unit, a forming platform, a liquid tank, a lifting column, a bottom film, photosensitive resin, and a base;

[0050] The control unit, the projection device, and the liquid tank are connected to the base; the motor is connected to the forming platform; the lifting column is fixedly connected to the base; the motor is installed on the lifting column to achieve electric drive lifting and drive the forming platform to lift or lower with it; the bottom film is arranged at the bottom of the liquid tank for light transmission; the liquid tank contains photosensitive resin liquid; the control unit is electrically connected to the projection device, the motor, the storage unit, and the display and operation unit; the storage unit stores the signature encrypted file; the control unit reads the signature encrypted file in the storage unit; the control unit performs SHA-256 verification, secondary decryption, primary decryption, and decompression on the signature encrypted file to obtain the plaintext of the printing parameters and the plaintext of the layer data. The control unit sets the plaintext of the printing parameters as the printing execution parameters and performs mask exposure layer by layer on the plaintext of the layer data; the control unit controls the motor to drive the forming platform to perform lifting movement according to the printing execution parameters; the user issues an operation instruction to the control unit through the display and operation unit, so that the control unit responds to the instruction and issues a control signal to control each controlled unit to complete the instruction action to achieve human-computer interaction operation; the control unit outputs signals and data to the display and operation unit to display the 3D model slice mask preview image, the printing movement execution parameters, the mask image exposure time parameters, the system setting options, and the system operation parameters; the control unit controls the motor to drive the forming platform to perform lifting movement according to the plaintext of the printing parameters; the control unit controls the projection device to light up the screen after loading the plaintext of the layer data and perform mask projection on it according to the plaintext of the printing parameters, and controls the projection device to turn off the screen; the projection device emits ultraviolet light and visible light projection passing through the image mask to expose and irradiate the photosensitive resin in the liquid tank through the bottom film to cure and form it; the forming platform is used to attach the cured model resin layer during the curing and forming process to continuously lift and grow until 3D printing is completed; the projection device uses an LCD projector or a DLP projector based on DMD digital micromirror technology; the 3D printing device uses an upward projection light curing 3D printer or a downward projection light curing 3D printer.

[0051] Compared with the prior art, the beneficial effects of the present invention are:

[0052] 1. The method 1 of the present invention provides an encryption method for 3D printing model slice files. Compressing the layer data generated after model slicing is beneficial to saving data storage space. Performing primary encryption and secondary encryption on the basis of data compression is beneficial to enhancing the data confidentiality effect.

[0053] 2. The method 1 of the present invention provides an encryption method for 3D printing model slice files. Directly performing secondary encryption on the parameter area of the model slice file is beneficial to further enhancing the confidentiality effect of the entire slice file;

[0054] 3. The method 1 of the present invention provides an encryption method for 3D printing model slice files. After performing SHA-256 signature, it is secondarily encrypted and then spliced at the end of the slice file, flowing with the encrypted slice file. This is beneficial to verifying the integrity of the slice data through the SHA-256 algorithm during the decryption process, preventing forced cracking or modification, and further enhancing the data integrity and security during the printing data transfer process.

[0055] 4. The method 1 of the present invention provides an encryption method for 3D printing model slice files. On the basis of primary encryption of each layer of data, randomly select discontinuous X layers for secondary encryption. When extracting discontinuous layers for secondary encryption, the secondary encrypted data of the data layer is not easily captured centrally through the method of dispersing the secondary encryption layers, so as to improve the overall data encryption and confidentiality effect, and it is not necessary to perform secondary encryption on all layers, which can reduce the computational workload during the encryption process and improve the computational efficiency of the entire encryption process.

[0056] 5. The method 1 of the present invention provides an encryption method for 3D printing model slice files. On the basis of primary encryption of each layer of data, randomly select discontinuous X layers for secondary encryption within the range of 11%-89% of the total layer number in sequence; concentrate the secondary encryption layers within the middle range of 11%-89% of the total layer number. After an illegal user forcibly cracks the primary encrypted data and cannot crack the secondary encrypted data, the printing fails when it reaches about half, which can increase the time cost and material cost of the failed printing, thereby enhancing the overall encryption and confidentiality effect.

[0057] 6. The method 2 of the present invention provides a decryption and printing method for 3D printing model slice files. This method is controlled and run by the control unit of the 3D printing device, enabling the 3D printing device to decrypt, identify, read, and execute printing on the slice files encrypted by method 1.

[0058] 7. The method 2 of the present invention provides a decryption and printing method for 3D printing model slice files. In steps 3, 4, and 5 of this method, first, the control unit determines whether the key information in its firmware matches the key information in the signature encrypted file, and then performs decryption and printing, which is beneficial to ensuring that the 3D printing can effectively identify and decrypt the corresponding signature encrypted file, and at the same time can also solve the compatibility discrimination problem of signature encrypted files for different printers of the same brand to ensure the smooth progress of the subsequent printing process.

[0059] 8. The method 2 of the present invention provides a decryption and printing method for 3D printing model slice files. During the decryption process, the integrity of the slice data is verified through the SHA-256 algorithm, preventing forced cracking or modification.

[0060] 9. The encryption method of Method 1 of the present invention is used in conjunction with the decryption and printing method of Method 2, which can meet the enterprise's need to strengthen the protection of original works. In the data distribution and sample printing trial process, the specified 3D printer is authorized with a serial number to become an authorized printing terminal, so as to achieve limited printing under intellectual property authorization. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a flowchart of the encryption method for the 3D printing model slice file of the present invention;

[0062] Figure 2 It is a flowchart of the decryption and printing method for the 3D printing model slice file of the present invention;

[0063] Figure 3 It is a principle block diagram of six states in the encryption process of the 3D printing model slice file of the present invention;

[0064] Figure 4 It is a schematic diagram of the 3D printing model slice of the present invention;

[0065] Figure 5 It is an embodiment of the layer data compression process of the 3D printing model slice file of the present invention;

[0066] Figure 6 is a schematic diagram of the 3D printing model slice processing and the use of the signed and encrypted file of the present invention;

[0067] Figure 7 It is a structural schematic diagram of the 3D printing device 1 applying the decryption and printing method of the present invention;

[0068] Figure 8 It is a structural schematic diagram of the 3D printing device 2 applying the decryption and printing method of the present invention;

[0069] Reference Numeral Description:

[0070] Control unit 1; LCD screen 2; Motor 3; Lifting column 31; Storage unit 4; UVLED light source module 5; Display and operation unit 6; Forming platform 7; Liquid tank 8; Bottom film 80; Photosensitive resin 81; Model forming resin layer 82; Base 9; Projection device 250. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0071] The following further describes the embodiments of the present invention with reference to the drawings.

[0072] Figure 1 It is a flowchart of the encryption method for the 3D printing model slice file of the present invention. As shown in the figure, it includes the following steps:

[0073] S01. The user performs slicing processing and saves the 3D model through 3D slicing software to obtain a first slice file with multiple layer data;

[0074] S02. The 3D slicing software compresses and encodes the multi-layer data of the first slicing file to obtain a second slicing file with multiple compressed layer data;

[0075] S03. The 3D slicing software performs primary encryption on the multiple compressed layer data of the second slicing file to obtain a third slicing file with multiple primary encrypted compressed layer data;

[0076] S04. The 3D slicing software performs secondary encryption on the parameter area of the third slicing file to obtain a fourth slicing file;

[0077] S05. The 3D slicing software randomly extracts non-consecutive X layers from the primary encrypted compressed layer data in the fourth slicing file for secondary encryption to obtain a fifth slicing file;

[0078] S06. The 3D slicing software performs SHA-256 operation on the part other than the identification file header in the fifth slicing file and performs secondary encryption on the operation result to obtain a SHA-256 encrypted signature;

[0079] S07. The 3D slicing software splices the SHA-256 encrypted signature at the end of the fifth slicing file to form an overall signature encrypted file;

[0080] S08. The 3D slicing software completes the final storage and renaming of the signature encrypted file at the specified storage path;

[0081] S09. The process ends.

[0082] Figure 2 This is the flowchart of the decryption and printing method for the 3D printing model slicing file of the present invention. As shown in the figure, it includes the following steps:

[0083] SS01. The user imports the signature encrypted file into the storage unit of the stereolithography printing device;

[0084] SS02. The control unit reads the signature encrypted file in the storage unit;

[0085] SS03. The control unit determines whether the magic number in its firmware matches the magic number in the identification file header of the signature encrypted file; if it is determined that the magic number in the control unit's firmware does not match the magic number in the identification file header of the signature encrypted file, then go to step SS16; if it is determined that the magic number in the control unit's firmware matches the magic number in the identification file header of the signature encrypted file, then go to step SS04;

[0086] SS04. The control unit determines whether the slice format version list in its firmware supports the slice format version in the identification file header of the signed and encrypted file; if it is determined that the slice format version list in the control unit's firmware does not support the slice format version in the identification file header of the signed and encrypted file, then step SS16 is performed; if it is determined that the slice format version list in the control unit's firmware supports the slice format version in the identification file header of the signed and encrypted file, then step SS05 is performed;

[0087] SS05. The control unit determines whether the OS version number in its firmware matches the OS version number in the identification file header of the signed and encrypted file; if it is determined that the OS version number in the control unit's firmware does not match the OS version number in the identification file header of the signed and encrypted file, then step SS16 is performed; if it is determined that the OS version number in the control unit's firmware matches the OS version number in the identification file header of the signed and encrypted file, then step SS06 is performed;

[0088] SS06. The control unit performs secondary decryption on the SHA-256 encrypted signature in the signed and encrypted file to obtain the string M1;

[0089] SS07. The control unit performs SHA-256 operation on the part other than the identification file header and signature in the signed and encrypted file to obtain the string M2;

[0090] SS08. The control unit determines whether the strings M1 and M2 are the same; if it is determined that the strings M1 and M2 are different, then step SS16 is performed; if it is determined that the strings M1 and M2 are the same, then step SS09 is performed;

[0091] SS09. The control unit performs secondary decryption on the parameters in the secondary encryption parameter area and correspondingly sets the plaintext of each decrypted parameter as the printing execution parameter of the control unit;

[0092] SS10. The control unit sequentially reads the slice data of the Nth layer;

[0093] SS11. The control unit determines whether the read layer slice data is secondarily encrypted; if it is determined that the read layer slice data is not secondarily encrypted, then step SS13 is performed; if it is determined that the read layer slice data has been secondarily encrypted, then step SS12 is performed;

[0094] SS12. The control unit performs secondary decryption on the read layer slice data;

[0095] SS13. The control unit first performs primary decryption and decompression on the read layer slice data and then performs exposure printing on the obtained plaintext of the layer slice data;

[0096] SS14. The control unit determines whether all layer slice data has been completely exposed and printed. If it is determined that all layer slice data has been completely exposed and printed, proceed to step SS17. If it is determined that not all layer slice data has been completely exposed and printed, proceed to step SS15.

[0097] SS15. The control unit sequentially reads the slice data of the (N + 1)-th layer, and then proceeds to step SS11.

[0098] SS16. The control unit sends out an error signal and exits the program.

[0099] SS17. The process ends.

[0100] Specifically, for the three judgment steps SS03, SS04, and SS05 in this figure, the judgment contents can be interchanged with each other, and the overall decryption and printing process execution result is not affected after the order is interchanged.

[0101] Figure 3 This is the principle block diagram of the six states in the encryption process of the 3D printing model slice file of the present invention. As shown in the figure, the six states of the slice file in its encryption process respectively correspond to Figure 3 .1, Figure 3 .2, Figure 3 .3, Figure 3 .4, Figure 3 .5, Figure 3 .6;

[0102] Figure 3 .1. The first slice file corresponds to step 1 of the encryption method of the present invention, and it includes: a file header, a preview image, and layer slice data. Among them, the file header further includes: an identification file header and a parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction sequences and their corresponding layer data; among them, each layer data header is an index of its corresponding layer data.

[0103] Figure 3 .2. The second slice file corresponds to step 2 of the encryption method of the present invention, and it includes: a file header, a preview image, and layer slice data. Among them, the file header further includes: an identification file header and a parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction sequences and their corresponding compressed layer data; among them, each layer data header is an index of its corresponding compressed layer data.

[0104] Figure 3The third slice file in .3 corresponds to Step 4 of the encryption method of the present invention, and it includes: a file header, a preview image, and layer slice data; wherein, the file header further includes: an identification file header and a parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction sequences and their corresponding first-level encrypted and compressed layer data; wherein, each layer data header is an index of its corresponding first-level encrypted and compressed layer data;

[0105] Figure 3 The fourth slice file in .4 corresponds to Step 4 of the encryption method of the present invention, and it includes: a file header, a preview image, and layer slice data; wherein, the file header further includes: an identification file header and a second-level encryption parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction sequences and their corresponding first-level encrypted and compressed layer data; wherein, each layer data header is an index of the layer data of its corresponding first-level encrypted and compressed layer data;

[0106] Figure 3 The fifth slice file in .5 corresponds to Step 5 of the encryption method of the present invention, and it includes: a file header, a preview image, and layer slice data; wherein, the file header further includes: an identification file header and a second-level encryption parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction sequences and their corresponding first-level encrypted and compressed layer data, and a plurality of layer data headers with spaced construction sequences and their corresponding second-level encrypted and compressed layer data; wherein, each layer data header is an index of its corresponding first-level encrypted and compressed layer data or second-level encrypted and compressed layer data;

[0107] Figure 3 The signature encryption file in .6 corresponds to Steps 6 and 7 of the encryption method of the present invention, and it includes: a file header, a preview image, layer slice data, and a SHA-256 encrypted signature; wherein, the file header further includes: an identification file header and a second-level encryption parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction sequences and their corresponding first-level encrypted and compressed layer data, and a plurality of layer data headers with spaced construction sequences and their corresponding second-level encrypted and compressed layer data; wherein, each layer data header is an index of its corresponding first-level encrypted and compressed layer data or second-level encrypted and compressed layer data; after the contents of these three parts, namely the second-level encryption parameter area, the preview image, and the layer slice data, are subjected to SHA-256 operation, the operation result is then second-level encrypted to obtain the SHA-256 encrypted signature; the SHA-256 encrypted signature is concatenated at the end of the fifth slice file.

[0108] Figure 4Schematic diagram of slicing the 3D printing model of the present invention. As shown in the figure, the slicing process corresponds to Figure 4 .1, Figure 4 .2;

[0109] Figure 4 In.1, the user slices the cuboid in the figure into 7 layers according to the set layer thickness parameter on the Z-axis by slicing software;

[0110] Figure 4 In.2, after the user slices the cuboid into 7 layers by the operation of Figure 4 .1, 7 slice layer pictures and layer data at the cross-section position of the slice are obtained; each slice layer picture in the figure is a mask picture with black around, gray value of 0, capable of blocking light, white in the center, gray value of 255, and capable of transmitting light.

[0111] Figure 5 This is an embodiment of the layer data compression process of the 3D printing model slice file of the present invention. As shown in the figure, it demonstrates the process of compressing and encoding layer data through Figure 5 .1, Figure 5 .2, Figure 5 .3, Figure 5 .4;

[0112] Figure 5 In.1, its layer picture corresponds to Figure 4 a certain layer picture of

[0113] Figure 5 .2, for example, it corresponds to the 007th layer mask picture; Figure 5 In.2, its layer data corresponds to the layer picture of

[0114] Figure 5 .1. Since the surrounding of its picture is black, the gray value is 0, and since the center is white, the gray value is 255; Figure 5 In.3, on the basis of

[0115] Figure 5 .2, the gray value 0 is defined as digital 0, and the gray value 255 is defined as digital 1, then the continuous data row shown in the figure is formed; Figure 5.3, taking its topmost row as an example, if the digit 0 is extracted and the quantity is 24, it can be compressed into an 8-bit binary compressed data segment represented as 10011000, which is represented as 0x18 after conversion to hexadecimal. By analogy, all other all-zero rows of data are recorded as 0x18; taking any non-all-zero row in the middle as an example, if the digits 0, 1, 0 are extracted and the quantities are 8, 8, 8 respectively, they can be compressed into 8-bit binary compressed data segments represented as 00001000, 10001000, 00001000 respectively, which are represented as 0x08, 0x88, 0x08 after conversion to hexadecimal, and then they are concatenated in order to 0x088808. By analogy, all other non-all-zero rows of data are recorded as 0x088808;

[0116] Taking Figure 5 .4's first row of the embodiment as an example, the repeated single digit 0 in the first row of continuous data segments is stored in the highest bit of the compressed data segment; the count value 24 is stored in the lower 7 bits of the compressed data segment; among them, the continuous data segment is a data segment composed of continuous single digits 0, and the compressed data segment includes a single digit 0 and the repetition times 24. When decrypting and printing, perform reverse calculation and decoding on the compressed data segment according to Figure 5 .4's embodiment to obtain the continuous data segment, forming layer data as shown in Figure 5 .2 and a mask picture as shown in Figure 5 .1. It should be understood that Figure 5 .4's embodiment is only a way of layer data compression and encoding, used to exemplify, elaborate and explain the content of layer data compression and encoding in step 2 of method 1, rather than a limitation of this invention.

[0117] Figure 6 is a schematic diagram of the 3D printing model slicing process and the use of the signed encrypted file of the present invention. As shown in the figure, it demonstrates the 3D printing model slicing process and the use of the signed encrypted file through Figure 6.1 , Figure 6.2 ;

[0118] Figure 6.1 Among them, after the user runs the 3D slicing software on the computer to load the model, sets the layer thickness parameter and other printing parameters, performs slicing processing and saves the first slice file with multiple layers of data; then the 3D slicing software performs layer data compression and encoding, first-level encryption, second-level encryption, and SHA-256 operation signature on the first slice file according to method 1 of the present invention, and then concatenates the SHA-256 encrypted signature at the end of the fifth slice file to form an overall signed encrypted file;

[0119] Figure 6.2 Among them, the user uses a storage device such as an SD card to Figure 6.1 import the finally obtained signed encrypted file in into the stereolithography 3D printing device, and it decrypts and prints according to method 2 of the present invention.

[0120] Figure 7 It is a structural schematic diagram of a 3D printing device 1 applying the decryption printing method of the present invention. As shown in the figure, the 3D printing device 1 includes: a control unit 1, an LCD screen 2, a motor 3, a storage unit 4, a UVLED light source module 5, a display and operation unit 6, a forming platform 7, a liquid tank 8, a lifting column 31, a bottom film 80, a photosensitive resin 81, and a base 9;

[0121] The control unit 1, the LCD screen 2, the UVLED light source module 5, and the liquid tank 8 are arranged and connected to the base 9; the motor 3 is connected to the forming platform 7; the lifting column 31 is fixedly connected to the base 9; the motor 3 is installed on the lifting column 31 to realize electric drive lifting and drive the forming platform 7 to lift or lower with it; the bottom film 80 is arranged at the bottom of the liquid tank 8 for light transmission; the liquid tank 8 contains the photosensitive resin 81 liquid; the control unit 1 is electrically connected to the LCD screen 2, the motor 3, the storage unit 4, the UVLED light source module 5, and the display and operation unit 6; the storage unit 4 stores the signature encrypted file; the control unit 1 reads the signature encrypted file in the storage unit 4; the control unit 1 performs SHA-256 verification, secondary decryption, primary decryption, and decompression on the signature encrypted file to obtain the plaintext of the printing parameters and the plaintext of the layer data. The control unit 1 sets the plaintext of the printing parameters as the printing execution parameters, and performs mask exposure layer by layer on the plaintext of the layer data; the control unit 1 controls the motor 3 to drive the forming platform to perform lifting movement according to the printing execution parameters; the user issues an operation instruction to the control unit 1 through the display and operation unit 6, so that the control unit 1 responds to the instruction and issues a control signal to control each controlled unit to complete the instruction action to realize the man-machine interaction operation; the control unit 1 outputs signals and data to the display and operation unit 6 to display the 3D model slice mask preview image, the printing movement execution parameters, the mask image exposure time parameters, the system setting options, and the system operation parameters; the control unit 1 controls the motor 3 to drive the forming platform 7 to perform lifting movement according to the plaintext of the printing parameters; the control unit 1 controls the UVLED light source module 5 to turn on or off the light; the UVLED light source module 5 emits ultraviolet light and visible light, which passes through the mask image in the LCD screen 2 and the bottom film 80 to expose and irradiate the photosensitive resin 81 in the liquid tank 8 to cure and form; the forming platform 7 is used to attach the cured model resin layer 82 during the curing and forming process to continuously lift and grow until the 3D printing is completed; the 3D printing device adopts an upward LCD light-curing 3D printer or a downward LCD light-curing 3D printer.

[0122] Figure 8The structural schematic diagram of the 3D printing device 2 applying the decryption and printing method of the present invention is shown as follows. As shown in the figure, the 3D printing device 2 includes: a control unit 1, a projection device 250, a motor 3, a storage unit 4, a display and operation unit 6, a forming platform 7, a liquid tank 8, a lifting column 31, a bottom film 80, a photosensitive resin 81, and a base 9;

[0123] The control unit 1, the projection device 250, and the liquid tank 8 are arranged and connected to the base 9; the motor 1 is connected to the forming platform 7; the lifting column 31 is fixedly connected to the base 9; the motor 3 is installed on the lifting column 31 to realize electric drive for lifting and drive the forming platform 7 to lift or lower along with it; the bottom film 80 is arranged at the bottom of the liquid tank 8 for light transmission; the liquid tank 8 contains the photosensitive resin 81 liquid; the control unit 1 is electrically connected to the projection device 250, the motor 3, the storage unit 4, and the display and operation unit 6; the storage unit 4 stores the signature encrypted file; the control unit 1 reads the signature encrypted file in the storage unit 4; the control unit 1 performs SHA-256 verification, secondary decryption, primary decryption, and decompression on the signature encrypted file to obtain the plaintext of the printing parameters and the plaintext of the layer data. The control unit 1 sets the plaintext of the printing parameters as the printing execution parameters, and performs mask exposure layer by layer on the plaintext of the layer data; the control unit 1 controls the motor 3 to drive the forming platform 7 to perform lifting movement according to the printing execution parameters; the user issues an operation instruction to the control unit 1 through the display and operation unit 6, so that the control unit 1 responds to the instruction and issues a control signal to control each controlled unit to complete the instruction action to realize the man-machine interaction operation; the control unit 1 outputs signals and data to the display and operation unit 6 to display the 3D model slice mask preview image, the printing movement execution parameters, the mask image exposure time parameters, the system setting options, and the system operation parameters; the control unit 1 controls the motor 3 to drive the forming platform 7 to perform lifting movement according to the plaintext of the printing parameters; the control unit 1 controls the projection device 250 to load the plaintext of the layer data and then turn on the screen and perform mask projection on it according to the plaintext of the printing parameters, and controls the projection device to turn off the screen; the projection device 250 emits ultraviolet light and visible light after image masking and projects through the bottom film 80 to expose and irradiate the photosensitive resin 81 in the liquid tank 8 to cure and form; the forming platform 7 is used to attach the cured model resin layer 82 during the curing and forming process and continuously lift and grow until the 3D printing is completed; the projection device 250 adopts an LCD projector or a DLP projector based on DMD digital micromirror technology; the 3D printing device adopts an upward projection light curing 3D printer or a downward projection light curing 3D printer.

[0124] The above embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the spirit of the present invention's design, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. An encryption method for 3D printing model slice files, characterized in that, it includes the following steps: S01. The user processes and saves the 3D model through 3D slicing software to obtain a first slice file with multiple layers of data; S02. The 3D slicing software compresses and encodes the multiple layers of data of the first slice file to obtain a second slice file with multiple compressed layers of data; S03. The 3D slicing software performs primary encryption on the multiple compressed layers of data of the second slice file to obtain a third slice file with multiple primary encrypted compressed layers of data; S04. The 3D slicing software performs secondary encryption on the parameter area of the third slice file to obtain a fourth slice file; S05. The 3D slicing software randomly extracts non - consecutive X layers from the primary encrypted compressed layers of data in the fourth slice file for secondary encryption to obtain a fifth slice file; S06. The 3D slicing software performs SHA - 256 operation on the part other than the identification file header in the fifth slice file and performs secondary encryption on the operation result to obtain a SHA - 256 encrypted signature; S07. The 3D slicing software concatenates the SHA - 256 encrypted signature at the end of the fifth slice file to form an overall signature - encrypted file; S08. The 3D slicing software completes the final storage and renaming of the signature - encrypted file at the specified storage path; S09. The process ends.

2. The encryption method for 3D printing model slice files according to claim 1, characterized in that, the first slice file includes: a file header, a preview image, and layer slice data; among them, the file header further includes: an identification file header and a parameter area; the preview image further includes: a large - size preview image and a small - size preview image; the layer slice data further includes: multiple layer data headers with consecutive construction sequences and their corresponding layer data; where each layer data header is an index of its corresponding layer data; the second slice file includes: a file header, a preview image, and layer slice data; among them, the file header further includes: an identification file header and a parameter area; the preview image further includes: a large - size preview image and a small - size preview image; the layer slice data further includes: multiple layer data headers with consecutive construction sequences and their corresponding compressed layer data; where each layer data header is an index of its corresponding compressed layer data; the third slice file includes: a file header, a preview image, and layer slice data; among them, the file header further includes: an identification file header and a parameter area; the preview image further includes: a large - size preview image and a small - size preview image; the layer slice data further includes: multiple layer data headers with consecutive construction sequences and their corresponding primary encrypted compressed layer data; where each layer data header is an index of its corresponding primary encrypted compressed layer data; the fourth slice file includes: a file header, a preview image, and layer slice data; among them, the file header further includes: an identification file header and a secondary encrypted parameter area; the preview image further includes: a large - size preview image and a small - size preview image; the layer slice data further includes: multiple layer data headers with consecutive construction sequences and their corresponding primary encrypted compressed layer data; where each layer data header is an index of its corresponding primary encrypted compressed layer data layer data; The fifth slice file includes: a file header, a preview image, and layer slice data; wherein, the file header further includes: an identification file header and a secondary encryption parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction sequences and their corresponding first-level encrypted and compressed layer data, and a plurality of layer data headers with intermittent construction sequences and their corresponding second-level encrypted and compressed layer data; wherein, each layer data header is an index of its corresponding first-level encrypted and compressed layer data or second-level encrypted and compressed layer data. The signature encrypted file includes: a file header, a preview image, layer slice data, and a SHA-256 encrypted signature; wherein, the file header further includes: an identification file header and a secondary encryption parameter area; the preview image further includes: a large-size preview image and a small-size preview image; the layer slice data further includes: a plurality of layer data headers with consecutive construction sequences and their corresponding first-level encrypted and compressed layer data, and a plurality of layer data headers with intermittent construction sequences and their corresponding second-level encrypted and compressed layer data; wherein, each layer data header is an index of its corresponding first-level encrypted and compressed layer data or second-level encrypted and compressed layer data; after the contents of the three parts of the secondary encryption parameter area, the preview image, and the layer slice data are subjected to SHA-256 operation, the operation result is then secondarily encrypted to obtain the SHA-256 encrypted signature; the SHA-256 encrypted signature is concatenated at the end of the fifth slice file.

3. A method for encrypting a 3D printing model slice file according to claim 1, characterized in that the method adopted for the first-level encryption includes: a transposition cipher algorithm, or a shift cipher algorithm; the methods adopted for the second-level encryption include: an AES encryption algorithm, or an RSA encryption algorithm, or a DES encryption algorithm, or an ECC encryption algorithm.

4. A method for encrypting a 3D printing model slice file according to claim 1, characterized in that when the 3D slicing software randomly extracts X non-consecutive layers from the first-level encrypted and compressed layer data in the fourth slice file for secondary encryption, the number of layers of the randomly extracted X layers is concentrated within the range of 11% - 89% of the total layer sequence; the value of X is a specified positive integer.

5. A method for encrypting a 3D printing model slice file according to claim 1, characterized in that when the 3D slicing software compresses and encodes the multiple layer data of the first slice file to obtain a second slice file with multiple compressed layer data, the rules for compressing and encoding the layer data include: storing the repeated single digit in the highest bit of the compressed data segment for the continuous data segment, and storing the count value in the lower 7 bits of the compressed data segment; or, storing the repeated single digit in the lowest bit of the compressed data segment for the continuous data segment, and storing the count value in the higher 7 bits of the compressed data segment; wherein, the continuous data segment is a data segment composed of consecutive single digits, and the compressed data segment includes the value of the single digit and the number of repetitions.

6. A method for decrypting and printing a 3D printing model slice file, characterized in that it includes the following steps: SS01. The user imports the signature encrypted file into the storage unit of the stereolithography printing device; SS02. The control unit reads the signed encrypted file in the storage unit; SS03. The control unit determines whether the magic number in its firmware matches the magic number in the identification file header of the signed encrypted file; if it is determined that the magic number in the control unit's firmware does not match the magic number in the identification file header of the signed encrypted file, step SS16 is performed; if it is determined that the magic number in the control unit's firmware matches the magic number in the identification file header of the signed encrypted file, step SS04 is performed; SS04. The control unit determines whether the slice format version list in its firmware supports the slice format version in the identification file header of the signed encrypted file; If it is determined that the slice format version list in the control unit's firmware does not support the slice format version in the identification file header of the signed encrypted file, step SS16 is performed; If it is determined that the slice format version list in the control unit's firmware supports the slice format version in the identification file header of the signed encrypted file, step SS05 is performed; SS05. The control unit determines whether the OS version number in its firmware matches the OS version number in the identification file header of the signed encrypted file; if it is determined that the OS version number in the control unit's firmware does not match the OS version number in the identification file header of the signed encrypted file, step SS16 is performed; if it is determined that the OS version number in the control unit's firmware matches the OS version number in the identification file header of the signed encrypted file, step SS06 is performed; SS06. The control unit performs secondary decryption on the SHA-256 encrypted signature in the signed encrypted file to obtain the string M1; SS07. The control unit performs SHA-256 operation on the part other than the identification file header and signature in the signed encrypted file to obtain the string M2; SS08. The control unit determines whether the strings M1 and M2 are the same; if it is determined that the strings M1 and M2 are different, step SS16 is performed; if it is determined that the strings M1 and M2 are the same, step SS09 is performed; SS09. The control unit performs secondary decryption on the parameters in the secondary encryption parameter area and correspondingly sets the plaintext of each decrypted parameter as the printing execution parameters of the control unit; SS10. The control unit sequentially reads the slice data of the Nth layer; SS11. The control unit determines whether the read layer slice data is secondarily encrypted; If it is determined that the read layer slice data is not secondarily encrypted, step SS13 is performed; if it is determined that the read layer slice data has been secondarily encrypted, step SS12 is performed; SS12. The control unit performs secondary decryption on the read layer slice data; SS13. The control unit first performs primary decryption and decompression on the read layer slice data and then performs exposure printing on the obtained plaintext of the layer slice data; SS14. The control unit determines whether all layer slice data has been completely exposed and printed; If it is determined that all layer slice data has been completely exposed and printed, step SS17 is performed; if it is determined that all layer slice data has not been completely exposed and printed, step SS15 is performed; SS15. The control unit sequentially reads the slice data of the (N + 1)-th layer, and the next step is to perform step SS11; SS16. The control unit sends out an error signal externally and exits the program; SS17. The process ends.

7. A decryption and printing method for a 3D printing model slice file according to claim 6, wherein, between the steps SS03, SS04, SS05 and their respective step contents, there are also multiple combined corresponding relationships generated by swapping the step contents in a permutation and combination manner.

8. A decryption and printing method for a 3D printing model slice file according to claim 6, wherein, the methods adopted for the primary decryption include: substitution cipher algorithm, or shift cipher algorithm; the methods adopted for the secondary decryption include: AES encryption algorithm, or RSA encryption algorithm, or DES encryption algorithm, or ECC encryption algorithm; N is a positive integer starting from 1 and increasing.

9. A 3D printing device applying the decryption and printing method for a 3D printing model slice file according to claim 6, wherein, it includes: a control unit, an LCD screen, a motor, a storage unit, a UVLED light source module, a display and operation unit, a forming platform, a liquid tank, a lifting column, a bottom film, photosensitive resin, and a base; the control unit, the LCD screen, the UVLED light source module, and the liquid tank are arranged and connected to the base; the motor is connected to the forming platform; the lifting column is fixedly connected to the base; the motor is installed on the lifting column to realize electric drive for lifting and drive the forming platform to lift or lower along with it; the bottom film is arranged at the bottom of the liquid tank for light transmission; the liquid tank is filled with photosensitive resin liquid; the control unit is electrically connected to the LCD screen, the motor, the storage unit, the UVLED light source module, and the display and operation unit; the storage unit stores the signature encrypted file; the control unit reads the signature encrypted file in the storage unit; the control unit performs SHA-256 verification, secondary decryption, primary decryption, and decompression on the signature encrypted file to obtain the plaintext of the printing parameters and the plaintext of the layer data. The control unit sets the plaintext of the printing parameters as the printing execution parameters, and performs mask exposure layer by layer on the plaintext of the layer data; the control unit controls the motor to drive the forming platform to perform lifting motion according to the printing execution parameters; The user sends an operation instruction to the control unit through the display and operation unit, so that the control unit responds to the instruction and sends a control signal to control each controlled unit to complete the instruction action to realize human-computer interaction operation; the control unit outputs signals and data to the display and operation unit to display the mask preview image of the 3D model slice, the printing motion execution parameters, the mask image exposure time parameters, the system setting options, and the system operation parameters; the control unit controls the motor to drive the forming platform to perform lifting motion according to the plaintext of the printing parameters; The control unit controls the UVLED light source module to turn on or off; the UVLED light source module emits ultraviolet light and visible light, which passes through the mask image and the bottom film in the LCD screen to expose and irradiate the photosensitive resin in the liquid tank to cure and form; the forming platform is used to attach the formed resin layer of the model during the curing and forming process to continuously lift and grow until the 3D printing is completed; the 3D printing device uses an upward LCD light-curing 3D printer or a downward LCD light-curing 3D printer.

10. A decryption printing method for a 3D printing model slice file according to claim 6, and a 3D printing device applying the decryption printing method, characterized in that it includes: a control unit, a projection device, a motor, a storage unit, a display and operation unit, a forming platform, a liquid tank, a lifting column, a bottom film, a photosensitive resin, and a base; The control unit, the projection device, and the liquid tank are arranged and connected to the base; the motor is connected to the forming platform; the lifting column is fixedly connected to the base; the motor is installed on the lifting column to realize electric drive lifting and drive the forming platform to lift or lower with it; the bottom film is arranged at the bottom of the liquid tank for light transmission; the liquid tank contains photosensitive resin liquid; the control unit is electrically connected to the projection device, the motor, the storage unit, and the display and operation unit; the storage unit stores the signature encrypted file; the control unit reads the signature encrypted file in the storage unit; The control unit performs SHA-256 verification, secondary decryption, primary decryption, and decompression on the signature encrypted file to obtain the plaintext of the printing parameters and the plaintext of the layer data. The control unit sets the plaintext of the printing parameters as the printing execution parameters, and performs mask exposure layer by layer on the plaintext of the layer data; the control unit controls the motor to drive the forming platform to perform lifting movement according to the printing execution parameters. The user issues an operation instruction to the control unit through the display and operation unit, so that the control unit responds to the instruction and issues a control signal to control each controlled unit to complete the instruction action to realize human-computer interaction operation; the control unit outputs signals and data to the display and operation unit to display the mask preview image of the 3D model slice, the printing movement execution parameters, the mask image exposure time parameters, the system setting options, and the system operation parameters; the control unit controls the motor to drive the forming platform to perform lifting movement according to the plaintext of the printing parameters. The control unit controls the projection device to turn on the screen after loading the plaintext of the layer data and perform mask projection on it according to the plaintext of the printing parameters, and controls the projection device to turn off the screen; the projection device emits ultraviolet light and visible light that have passed through the image mask and projects through the bottom film to expose and irradiate the photosensitive resin in the liquid tank to cure and form; the forming platform is used to attach the formed resin layer of the model during the curing and forming process to continuously lift and grow until the 3D printing is completed; the projection device uses an LCD projector or a DLP projector based on DMD digital micromirror technology; the 3D printing device uses an upward projection light-curing 3D printer or a downward projection light-curing 3D printer.

Images