All printable characters [ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789ÄÖÜäööü are possible as the alphabet for the keyword. Thus, a distinction is made between upper and lower case letters. In this implementation the permutation from the keyword is determined as follows: All characters are identified by their ASCII value. Then the columns are read in the order of the numbers of the permutation. Afterwards 2 header lines are added: The first one contains the keyword, the second one consists of the numbers, which are obtained by arranging the characters in the keyword alphabetically (permutation). The plaintext is then entered into the grid line by line. The number of columns is given by the length of the key (also called keyword). In cryptography, transposition is a cipher where the order of the letters is changed instead of replacing the letters with other symbols as in the substitution cipher.Ĭolumn transposition uses a rectangular arrangement (also called a matrix or grid), consisting of several rows (as many as are necessary to enter the plain text). Print(decrypt_message(ssage, args.key, args.alphabet, args.case_sensitive)) Print(encrypt_message(ssage, args.key, args.case_sensitive, args.remove_spaces_mod, args.replace_char, args.blocks_of_five, args.alphabet)) Parser.add_argument("-m", "-message", help="char for replacement", type=str, required=True) Parser.add_argument('-rc','-replace-char', help="char for replacement", type=str) Parser.add_argument('-rs','-remove-spaces', dest='remove_spaces_mod', action='store_true') Parser.add_argument('-cs','-case-sensitive', dest='case_sensitive', action='store_true') Parser.add_argument('-f','-blocks-of-five', dest='blocks_of_five', action='store_true') Parser.add_argument('-d','-decrypt', dest='crypt_modus', action='store_false') Parser.add_argument('-e','-encrypt', dest='crypt_modus', action='store_true') Parser.add_argument("-k", "-key", help="key to decrypt or encrypt", type=str) Parser.add_argument("-a", "-alphabet", help="alphabet for key and inut-tex", type=str) #get every first,second and so on element from column in matrixĭecrypted_message += empty_matrix #if col is bigger than keylength minus diff it means that in this row is a placeholder on the last rowĮmpty_matrix += cipher #pointer that point on the row to insert char #remove non-alphabetic symbols in message and key # calculate the number of placeholders in the last row # append the columns based on the alphabetic order of the keyĮncrypted_message += "".join(column])Įncrypted_message = list(encrypted_message.replace(' ',''))Įncrypted_message = ''.join(list(chain(* + įor i in range(0, len(encrypted_message), N)])))ĭef decrypt_message(cipher, key, alphabet, b_case_sensitive): Sorted_key = sorted(ems(), key=lambda pair: alphabet.index(pair), reverse=False) # get every nth el and append to a column #if case sensitive is false, then set key to lowercase #escape all regex special characters in alphabet Message = message.replace(' ', replace_char) Please enter your text here' -key 'Cipher' -alphabet '' -case-sensitive -replace-char ''ĭef encrypt_message(message, key, b_case_sensitive ,b_remove_spaces, replace_char, b_blocks_of_five, alphabet): Python transpostion.py -encrypt -message 'Hello this is a test.
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