Decrypter

Decrypter After writing encrypter.py , you are to write a related program named decrypter.py . decrypter.py will take the name of a text file and index (key) file, and then it will decrypt the text. The program will read in these two files, and using the information stored within them, it will put the contents back in the original order. The decrypted file should be saved to a file named decrypted.txt Running decrypter.py will look like so: Enter the name of an encrypted text file: file_name_a Enter the name of the encryption index file: file_name_b Where file_name_a is the name of the encrypted file, and file_name_b is the name of the index file. You should use lists and the indexes from the index file to help with getting the lines back in the correct order. There will be multiple examples of running this program on the diff-testing tool. Make sure to test your code carefully using the tool! The encrypting algorithm The diff-testing site has several example runs of encrypter.py . The examples will include what we expect the encrypted file and the index file should look like. The contents of these files must match what we expect exactly. In order to get the outputs to match, you will need to follow the same encryption algorithm that is shown below. The steps of the algorithm are outlined below and you must implement these steps in python. Note that the below steps are just the steps for how to determine which lines to put where in the encrypted file. You also need to handle all of the file reading, writing, etc.    Import the random python library Initialize the random library with a seed value of 125 . (Just put the line of code random.seed(125) at the beginning of main). However many lines there are in the input text file, repeat the following steps (line_count * 5) times o Chose two random integers starting from zero and going up to the number of lines in the file minus 1 o Swap the content of the lines at these two indexes By choosing the seed 125 , you should get the same results if you follow the steps carefully. Code structure Below are suggestions for the sequence steps for both of the programs: encrypter.py       Set the random seed random.seed(125) Ask for a file name from the user Read the contents of the file into a list Create a list of indexes that is the same length as the list of lines in the file. This should be a list of numbers. Follow the encryption algorithm described earlier. Whenever you swap two lines in the lines list, also swap the indexes in the index list. After the encrypting process is complete, write the shuffled content of the lines list to encrypted.txt . Also, write the shuffled indexes from the index list to index.txt . Make sure to close both files! decrypter.py       Ask the user for the name of the encrypted file Ask the user for the name of the index file Read the contents of the encrypted and index file into a list. Write a loop that iterates through indexes 1 through the length of the file contents list. Using the index list, append the contents to a new list in the decryoted (original) order. Write the list out to a file named decrypted.txt . Code size For your reference, my solution to encrypter.py is around 43 lines of code, not including comments, and my solution for decrypter.py is around 26 lines of code (not including comments). This information is meant to be encouraging, and keep you on the correct track. The code to be written is not very long. However, getting the encryption loop and decryption loop correct might be tricky, so start early! Some files from the test cases     sample.txt poem.txt few-steps.txt many-steps.txt Submission and grading It is due on Tuesday, March 31, at 7:00pm. You should put all of your code in two python files, named encrypter.py and decrypter.py . You only nede to upload these two files to gradescope for this PA. Submit these files to Gradescope, and try your best to write your programs in such a way that they pass every test case. Answer: def main(): encrypted_filename = input('Enter the name of an encrypted text file: \n') encrypted_index_filename = input('Enter the name of the encryption index file: \n') encrypted_file = open(encrypted_filename, 'r') encrypted_index_file = open(encrypted_index_filename, 'r') encrypted_lines = encrypted_file.readlines() encrypted_index = encrypted_index_file.readlines() new_index_list = []#create a list of index with original position, starting at 1. decrypted_list = [] for i in range(len(encrypted_lines)): new_index_list.append(i+1)#add the index into the list, since len starts at 0 => + 1 to i for num in new_index_list: #this loop will compare the number in the new_index_list with every number in the #previous index list from index.txt, until it finds the number that match. #After that, it will use that index and append the line that has the same index into #the decrypted_list. For example, num = 5, and encrypted_index[i] = 5 at i = 8 #then it will use i = 8 to append the line[i=8] to decrypted file. j = 1 while j <= len(encrypted_lines) and num != int(encrypted_index[j-1]): j += 1 # this loop will make sure 'j' will keep adding 1, until it matches if j <= len(encrypted_lines): decrypted_list.append(encrypted_lines[j -1]) encrypted_file.close() encrypted_index_file.close() decrypted_file = open('decrypted.txt','w') for num in range(len(decrypted_list)): #write the decrypted lines to file decrypted_file.write(str(decrypted_list[num])) decrypted_file.close() main()