├── SECURITY.md
├── .github
    └── ISSUE_TEMPLATE
    │   └── bug_report.md
├── LICENSE
├── README.md
├── CODE_OF_CONDUCT.md
└── decrypter.c


/SECURITY.md:
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1 | There is no security here 😂😂
2 | 


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/.github/ISSUE_TEMPLATE/bug_report.md:
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 1 | ---
 2 | name: Bug report
 3 | about: Create a report to help us improve
 4 | title: ''
 5 | labels: ''
 6 | assignees: ''
 7 | 
 8 | ---
 9 | 
10 | **Describe the bug**
11 | A clear and concise description of what the bug is.
12 | 
13 | **To Reproduce**
14 | Steps to reproduce the behavior:
15 | 1. Go to '...'
16 | 2. Click on '....'
17 | 3. Scroll down to '....'
18 | 4. See error
19 | 
20 | **Expected behavior**
21 | A clear and concise description of what you expected to happen.
22 | 
23 | **Screenshots**
24 | If applicable, add screenshots to help explain your problem.
25 | 
26 | **Desktop (please complete the following information):**
27 |  - OS: [e.g. iOS]
28 |  - Browser [e.g. chrome, safari]
29 |  - Version [e.g. 22]
30 | 
31 | **Smartphone (please complete the following information):**
32 |  - Device: [e.g. iPhone6]
33 |  - OS: [e.g. iOS8.1]
34 |  - Browser [e.g. stock browser, safari]
35 |  - Version [e.g. 22]
36 | 
37 | **Additional context**
38 | Add any other context about the problem here.
39 | 


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/LICENSE:
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 1 | MIT License
 2 | 
 3 | Copyright (c) 2019 gilfoyle97
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


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/README.md:
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 1 | # fileDecrypter :lock:
 2 | **0010101010101001010 ---- Simple C file decrypter ---- 1010100101010101010001**
 3 | 
 4 | **Disclaimer**: This was a part of a University project (Operating System course), not a serious decrypter. 
 5 | 
 6 | Description :mega:
 7 | --------
 8 | 
 9 | fileDecrypter is able to read and edit binary files with a certain format.
10 | 
11 | More in detail, the program takes as input 3 arguments: the name of a file *fin*, the name of a file *fout* and a string *s*.  
12 | The file *fin* is a binary file of an obfuscated text, in which, for each memorized character, a 16 bit number is used, composed as follows: 0xy0<sub>16</sub>, where xy<sub>16</sub> is the ASCII code of the character.  
13 | The program must execute the command `/bin/sed -e s`, making sure that the standard input of this command is the content of the defluxed file (that is, removing the 4 bits to zero before and after each character).
14 | 
15 | The program then takes the result of the above command (on standard output), replaces (adding 4 bits to zero before and after each character) and write the result of this re-obfuscation on fout. Any written sed on standard error is ignored.
16 | 
17 | Only the following errors can occur:
18 | 
19 | - The program does not start with the required topics. 
20 | The program then ends with exit status 10 (without performing any action), and writing on standard error:
21 |             
22 |             Usage: p file sed script, where p is the name of the program itself.
23 |     
24 | - The file does not exist or is not accessible. 
25 | The program then ends with exit status 20 (without performing any action), and writing on standard error:
26 | 
27 |             Unable to r file f because of e, where e is the system string
28 |     
29 | which explains the error and r is read from if f is not accessible for reading, or write to if it is not accessible for writing.
30 | 
31 | - The file read is not well formatted: bits at 0 are missing in some positions where they should be.
32 | In this case, it ends with an exit status 30, generating the output up to the wrong byte excluded and writing on standard error:
33 | 
34 |             Wrong format for input binary file f at byte d
35 |     
36 | where d is the byte number (starting from 0) where the error occurs.
37 | 
38 | - Any other system call fails. The program ends with exit status 100 (without performing any other action), and writing on standard error:
39 | 
40 |             System call s failed because of e
41 |     
42 | where e is the system string that explains the error and s is the system call that failed.
43 | 
44 | Usage 🔧
45 | -------
46 | 
47 | - `gcc decrypter.c -o decrypter`
48 | - `./decrypter`
49 | 
50 | Download 📡
51 | -------
52 | 
53 | `git clone https://github.com/edoardottt/fileDecrypter.git`
54 | 
55 | 
56 | If you liked it drop a :star:
57 | --------
58 | 
59 | [edoardottt.com](https://edoardottt.com/) to contact me.
60 | 


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/CODE_OF_CONDUCT.md:
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 1 | # Contributor Covenant Code of Conduct
 2 | 
 3 | ## Our Pledge
 4 | 
 5 | In the interest of fostering an open and welcoming environment, we as
 6 | contributors and maintainers pledge to making participation in our project and
 7 | our community a harassment-free experience for everyone, regardless of age, body
 8 | size, disability, ethnicity, sex characteristics, gender identity and expression,
 9 | level of experience, education, socio-economic status, nationality, personal
10 | appearance, race, religion, or sexual identity and orientation.
11 | 
12 | ## Our Standards
13 | 
14 | Examples of behavior that contributes to creating a positive environment
15 | include:
16 | 
17 | * Using welcoming and inclusive language
18 | * Being respectful of differing viewpoints and experiences
19 | * Gracefully accepting constructive criticism
20 | * Focusing on what is best for the community
21 | * Showing empathy towards other community members
22 | 
23 | Examples of unacceptable behavior by participants include:
24 | 
25 | * The use of sexualized language or imagery and unwelcome sexual attention or
26 |  advances
27 | * Trolling, insulting/derogatory comments, and personal or political attacks
28 | * Public or private harassment
29 | * Publishing others' private information, such as a physical or electronic
30 |  address, without explicit permission
31 | * Other conduct which could reasonably be considered inappropriate in a
32 |  professional setting
33 | 
34 | ## Our Responsibilities
35 | 
36 | Project maintainers are responsible for clarifying the standards of acceptable
37 | behavior and are expected to take appropriate and fair corrective action in
38 | response to any instances of unacceptable behavior.
39 | 
40 | Project maintainers have the right and responsibility to remove, edit, or
41 | reject comments, commits, code, wiki edits, issues, and other contributions
42 | that are not aligned to this Code of Conduct, or to ban temporarily or
43 | permanently any contributor for other behaviors that they deem inappropriate,
44 | threatening, offensive, or harmful.
45 | 
46 | ## Scope
47 | 
48 | This Code of Conduct applies both within project spaces and in public spaces
49 | when an individual is representing the project or its community. Examples of
50 | representing a project or community include using an official project e-mail
51 | address, posting via an official social media account, or acting as an appointed
52 | representative at an online or offline event. Representation of a project may be
53 | further defined and clarified by project maintainers.
54 | 
55 | ## Enforcement
56 | 
57 | Instances of abusive, harassing, or otherwise unacceptable behavior may be
58 | reported by contacting the project team at edoardott@gmail.com. All
59 | complaints will be reviewed and investigated and will result in a response that
60 | is deemed necessary and appropriate to the circumstances. The project team is
61 | obligated to maintain confidentiality with regard to the reporter of an incident.
62 | Further details of specific enforcement policies may be posted separately.
63 | 
64 | Project maintainers who do not follow or enforce the Code of Conduct in good
65 | faith may face temporary or permanent repercussions as determined by other
66 | members of the project's leadership.
67 | 
68 | ## Attribution
69 | 
70 | This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
71 | available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
72 | 
73 | [homepage]: https://www.contributor-covenant.org
74 | 
75 | For answers to common questions about this code of conduct, see
76 | https://www.contributor-covenant.org/faq
77 | 


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/decrypter.c:
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  1 | #include <stdio.h>
  2 | #include <stdlib.h>
  3 | #include <unistd.h>
  4 | #include <sys/stat.h>
  5 | #include <sys/types.h>
  6 | #include <stdbool.h>
  7 | #include <string.h>
  8 | 
  9 | bool r;
 10 | bool w;
 11 | bool directory;
 12 | main(int argc, char *argv[])
 13 | {
 14 |   int i;
 15 |   if (argc != 4) /* Bad Input */
 16 |     {
 17 |       fprintf(stderr,"Usage %s file sed_script\n",argv[0]);exit(10);
 18 |     }
 19 |   struct stat fileStat;
 20 |   stat(argv[1],&fileStat);
 21 |   int len=fileStat.st_size;
 22 |   if ((S_ISDIR(fileStat.st_mode))) {directory=true;} else {directory=false;}        //check if it's a folder
 23 |   if ((fileStat.st_mode & S_IRUSR)>0)  {r=true;} else {r=false;}                    //check if it's accessible on reading
 24 |   if ((fileStat.st_mode & S_IWUSR)>0) {w=true;} else {w=false;}                     //check if it's accessible on writing
 25 |   /* File1 not accessible */
 26 |   if (!((!(directory))&& r && w))
 27 |     { char *re;
 28 |       if (r==false) {re="read from"; }
 29 |       else {if (w==false) {re="write to";}}
 30 |       fprintf(stderr,"Unable to %s file %s because of ",re,argv[1]);
 31 |       perror("Error");
 32 |       exit(20);
 33 |     }
 34 |     int ii;
 35 |     int appoggio[70000];
 36 |     FILE *file = fopen(argv[1],"rb");                                               //pointer to file.bin_in on reading
 37 |     int c;
 38 |     int contatore=0;
 39 |     int flag=1;
 40 |     int index1=0;
 41 |     while(contatore<len)                                                            //until contatore is less than file length
 42 |     {
 43 |       c = fgetc(file);                                                              //c = first available character in the file
 44 |       contatore++;
 45 |       for (ii = 0; ii < 8; ii++)
 46 |       {
 47 |           if (flag==1)                                                              //if I haven't to take first 4 bits
 48 |             {
 49 |               if (ii==0 || ii==1 || ii==2 || ii==3)                                 //if they aren't equal to 0
 50 |               {
 51 |                 if ((!!((c<<ii) & 0x80)) != 0)
 52 |                 {fprintf(stderr,"Wrong format for input binary file %s at byte %d\n",argv[1],contatore-1);
 53 |                 fclose(file); FILE *out= fopen(argv[2],"ab+");
 54 |                 if(out == NULL)                                                     //if the output file doesn't exist, create it
 55 |                 {freopen(argv[2], "ab+", out);}fclose(out);exit(30);
 56 |                 }
 57 |               }
 58 |               else if (ii==4 || ii==5 || ii==6 || ii==7)                            //instead those I store them in an array appoggio
 59 |               {
 60 |                 int app=!!((c<<ii) & 0x80);
 61 |                 appoggio[index1]=app;
 62 |                 index1++;                                                           //index1 = array appoggio index
 63 |               }
 64 |             }
 65 |           if (flag==2)                                                              //if I haven't to take second 4 bits
 66 |             {
 67 |               if (ii==4 || ii==5 || ii==6 || ii==7)                                 //if they aren't equal to 0
 68 |               {
 69 |                 if ((!!((c<<ii) & 0x80)) != 0)
 70 |                   {fprintf(stderr,"Wrong format for input binary file %s at byte %d\n",argv[1],contatore-1);
 71 |                   fclose(file); FILE *out= fopen(argv[2],"ab+");
 72 |                   if(out == NULL)                                                   //if the output file doesn't exist, create it
 73 |                   {freopen(argv[2], "ab+", out);}fclose(out);exit(30);
 74 |                   }
 75 |               }
 76 |               else if (ii==0 || ii==1 || ii==2 || ii==3)                            //instead those I store them in an array appogg
 77 |                 {
 78 |                   int app=!!((c<<ii) & 0x80);
 79 |                   appoggio[index1]=app;
 80 |                   index1++;
 81 |                 }
 82 |             }
 83 |           if (flag==1 && ii==7) {flag=2;}                                           //flag change when It 
 84 |           else {
 85 |                   if (flag==2 && ii==7) {flag=1;}
 86 |                }
 87 |       }
 88 |     }
 89 |     fclose(file);                                                                   // clean file input pointer
 90 |     char appoggio2[index1];
 91 |     unsigned char appoggio3;
 92 |     int index2=0;
 93 |     int iii=0;
 94 |     while (index2<index1)
 95 |       {
 96 |             appoggio3 = appoggio[index2]<<7 |
 97 |                         appoggio[index2+1]<<6 |
 98 |                         appoggio[index2+2]<<5 |
 99 |                         appoggio[index2+3]<<4 |
100 |                         appoggio[index2+4]<<3 |
101 |                         appoggio[index2+5]<<2 |                                     //REGROUP THE BITS INTO CHARACTERS
102 |                         appoggio[index2+6]<<1 |
103 |                         appoggio[index2+7]<<0;
104 |             appoggio2[iii]=appoggio3;
105 |             iii++;
106 |             index2=index2+8;
107 |       }
108 |     FILE *fp = fopen("temp.bin", "ab");                                             // fp = temporary file pointer
109 |     fwrite(appoggio2,1,iii,fp);                                                     // write appoggio2 into the temp file
110 |     fclose(fp);                                                                     // clean temp file
111 |    /*SED*/
112 |    char sedb[6000];                                                                 // sedb = final string
113 |    int cont=0;
114 |    int filedes[2];
115 |    pipe(filedes);
116 |    pid_t id_figlio = fork();
117 |    if ( id_figlio == 0)
118 |    {
119 |      dup2(filedes[1],STDOUT_FILENO);                                                 // if I am the child, I duplicate the stdout on the file descriptor
120 |      close(filedes[0]);
121 |      close(filedes[1]);
122 |      execl("/bin/sed","sed","-e",argv[3],"temp.bin",NULL);                           //execute sed
123 |    }
124 |    else
125 |    {
126 |      close(filedes[1]);
127 |      wait(NULL);                                                                      // processes sync.
128 |      int num=0;
129 |      while(true)
130 |      {
131 |        char temp[1];
132 |        int byte=read(filedes[0],temp,1);
133 |        if (byte<1) {break;}                                                           // Storing the result in sed
134 |        sedb[num]=temp[0];
135 |        num++;
136 |        cont++;
137 |      }
138 |      sedb[num]='\0';
139 |    }
140 |      int offuscato[100000];
141 |      int indice_sed=0;
142 |      int char_sed_off=0;
143 |      int indice_offuscato=0;
144 |      while (indice_sed<cont)
145 |      {                                                                                //First 8 bits for obfuscation
146 |        offuscato[indice_offuscato]=0;
147 |        offuscato[indice_offuscato+1]=0;
148 |        offuscato[indice_offuscato+2]=0;
149 |        offuscato[indice_offuscato+3]=0;
150 |        //characters writing as bytes
151 |        char character=sedb[indice_sed];
152 |        offuscato[indice_offuscato+4]=!!((character<<0) & 0x80);
153 |        offuscato[indice_offuscato+5]=!!((character<<1) & 0x80);
154 |        offuscato[indice_offuscato+6]=!!((character<<2) & 0x80);
155 |        offuscato[indice_offuscato+7]=!!((character<<3) & 0x80);
156 |        offuscato[indice_offuscato+8]=!!((character<<4) & 0x80);
157 |        offuscato[indice_offuscato+9]=!!((character<<5) & 0x80);
158 |        offuscato[indice_offuscato+10]=!!((character<<6) & 0x80);
159 |        offuscato[indice_offuscato+11]=!!((character<<7) & 0x80);
160 |        //last 4 bits for obfuscation
161 |        offuscato[indice_offuscato+12]=0;
162 |        offuscato[indice_offuscato+13]=0;
163 |        offuscato[indice_offuscato+14]=0;
164 |        offuscato[indice_offuscato+15]=0;
165 |        indice_offuscato=indice_offuscato+16;
166 |        indice_sed++;
167 |        char_sed_off=char_sed_off+2;
168 |      }
169 |      int ind_off=0;
170 |      int ind_sed=0;
171 |      unsigned char appoggio4;
172 |      char offuscamento[char_sed_off];
173 |      while(ind_sed<char_sed_off)
174 |      {                                                                                // final obfuscation
175 |        appoggio4 = offuscato[ind_off]<<7 |
176 |                    offuscato[ind_off+1]<<6 |
177 |                    offuscato[ind_off+2]<<5 |
178 |                    offuscato[ind_off+3]<<4 |
179 |                    offuscato[ind_off+4]<<3 |
180 |                    offuscato[ind_off+5]<<2 |
181 |                    offuscato[ind_off+6]<<1 |
182 |                    offuscato[ind_off+7]<<0;
183 |        offuscamento[ind_sed]=appoggio4;
184 |        ind_sed++;
185 |        ind_off=ind_off+8;
186 |      }
187 |      FILE *out;
188 |     out = fopen(argv[2],"ab+");                                                        // if the file.bin_out doesn't exist, create it
189 |     if(out == NULL)                                                                    // then write the obfuscated result in the output file
190 |     {                                                                                  // clean the output pointer and remove the temporary file
191 |         freopen(argv[2], "ab+", out);
192 |     }
193 |      fwrite(offuscamento,1,ind_sed,out);
194 |      fclose(out);
195 |      remove("temp.bin");
196 | }
197 | 


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