Whole code refactored

Author: Mehdi

main.py

@@ -0,0 +1,35 @@
+'''
+Implemented by: ALAOUI Mehdi 2013
+Code reviewed/cleaned: 2018
+
+Simple example of RandomEncryption's uses
+'''
+from random_encryption import RandomEncryption
+
+STRING_TO_ENCRYPT = 'Hello world, I\'m Mehdi.'
+STRING_TO_DECRYPT = None
+FILENAME = 'encryption_test.txt'
+
+#  1- Encryption:
+
+STRING_TO_DECRYPT = RandomEncryption().encrypt(STRING_TO_ENCRYPT)
+print('--- Encryption result ---')
+print(STRING_TO_DECRYPT)
+print('--- --- --- --- --- ---\n\n')
+
+# 2- Decryption:
+
+print('--- Decryption result ---')
+print(RandomEncryption().decrypt(STRING_TO_DECRYPT))
+print('--- --- --- --- --- ---\n\n')
+
+# 3- File use:
+
+print(f'--- Encryption result (also stored in {FILENAME} file) ---')
+print(RandomEncryption().encrypt(STRING_TO_ENCRYPT, FILENAME))
+print('--- --- --- --- --- ---\n\n')
+
+
+print(f'--- Decryption result (read from {FILENAME} file) ---')
+print(RandomEncryption().decrypt_from_file(FILENAME))
+print('--- --- --- --- --- ---\n\n')

program.py

@@ -0,0 +1,110 @@
+"""
+Encryption/Decryption Algorithm, conceived and implemented by: ALAOUI Mehdi 2013
+Code reviewed/cleaned: 2018
+"""
+import random
+
+'''
+RandomEncryption object is an 'API' to encrypt/decrypt string
+useable methods:
+    - encrypt(text, filename): returns a string containing encrypted value of 'text'
+        if filename specified, will write the result in it.
+    - encrypt_from_file(input_filename, output_filename): same use as 'encrypt' method, the first argument is a filename in which the text to encrypt will be read.
+
+    - decrypt(text, filename): same use as 'encrypt' method, for decrypting.
+    - decrypt_from_file(input_filename, output_filename): same use as 'encrypt_from_file', for decrypting.
+'''
+
+class RandomEncryption:
+
+    def decrypt_from_file(self, input_filename: str, output_filename: str = None) -> str:
+        text_to_decrypt = self._read(input_filename)
+        return self.decrypt(text_to_decrypt, output_filename)
+
+
+    def decrypt(self, text_to_decrypt: str, output_filename: str = None) -> str:
+        decrypted_text = ''
+        while len(text_to_decrypt) > 0:
+            i = 1
+            while i < len(text_to_decrypt) and ord(text_to_decrypt[i]) < 97:
+                i += 1
+            encrypted_sequence, text_to_decrypt = text_to_decrypt[1:i], text_to_decrypt[i:]
+            first_basis, second_basis = (
+                self._string_hex_to_int(encrypted_sequence[0]),
+                self._string_hex_to_int(encrypted_sequence[1]),
+            )
+            char_to_decrypt = encrypted_sequence[2:]
+            decrypted_char = self._revert_to_decimal_from_basis(first_basis,
+                self._revert_to_decimal_from_basis(second_basis, char_to_decrypt)
+            )
+            decrypted_text += chr(int(decrypted_char))
+        if output_filename:
+            self._write(output_filename, decrypted_text)
+        return decrypted_text
+
+    def encrypt_from_file(self, input_filename: str, output_filename: str = None) -> str:
+        text_to_encrypt = self._read(input_filename)
+        return self.encrypt(text_to_encrypt, output_filename)
+
+    def encrypt(self, text_to_encrypt: str, output_filename: str = None) -> str:
+        encrypted_text = ''
+        for char in text_to_encrypt:
+            first_basis, second_basis = self._get_random_int(2, 10), self._get_random_int(2, 16)
+            delimiter = self._get_random_char()
+            encrypted_char = self._revert_from_decimal_to_basis(second_basis, int(
+                self._revert_from_decimal_to_basis(first_basis, ord(char))
+            ))
+            first_basis = self._get_hex_value(first_basis)
+            second_basis = self._get_hex_value(second_basis)
+            encrypted_text += delimiter + first_basis + second_basis + encrypted_char
+        if output_filename:
+            self._write(output_filename, encrypted_text)
+        return encrypted_text
+
+    def _get_random_char(self, uppercase: bool = False):
+        _ascii = self._get_random_int(65, 90) if uppercase else self._get_random_int(97, 122)
+        return chr(_ascii)
+
+    @staticmethod
+    def _get_random_int(min_value: int, max_value: int) -> int:
+        return random.randint(min_value, max_value)
+
+    def _revert_from_decimal_to_basis(self, final_basis: int, number: int) -> str:
+        output_value = ''
+        while number > 0:
+            (rest, number) = (number % final_basis, number // final_basis)
+            rest = self._get_hex_value(rest)
+            output_value = rest + output_value
+        return output_value
+
+    def _revert_to_decimal_from_basis(self, initial_basis: int, number: int) -> str:
+        number, n = str(number), len(number)
+        output_value = 0
+        for index, digit in enumerate(number):
+            digit_value = self._string_hex_to_int(digit)
+            output_value += digit_value * (initial_basis ** (n - 1 - index))
+        return str(output_value)
+
+    @staticmethod
+    def _string_hex_to_int(hexa_value: str) -> int:
+        '''
+        Returns integer value of a hexa string. Ex. '1' -> 1, 'B' -> 11.
+        '''
+        return int(hexa_value) if ord(hexa_value) < 65 else (ord(hexa_value) - 55)
+
+    @staticmethod
+    def _get_hex_value(int_value: int) -> str:
+        return str(int_value) if int_value < 10 else chr(int_value + 55)
+
+    @staticmethod
+    def _read(filename):
+        _file = open(filename, 'r')
+        file_content = _file.read()
+        _file.close()
+        return file_content
+
+    @staticmethod
+    def _write(filename, value):
+        _file = open(filename, 'w')
+        _file.write(value)
+        _file.close()