Module licenseware.utils.aes

Classes

class AESCipher (key)

Usage:

password = 'secret'
text_to_encrypt = 'hello john'

aes = AESCipher(password)

encrypted_text = aes.encrypt(text_to_encrypt)
decrypted_text = aes.decrypt(encrypted_text)

Expand source code

class AESCipher:

    """
    Usage:
    ```py

    password = 'secret'
    text_to_encrypt = 'hello john'

    aes = AESCipher(password)

    encrypted_text = aes.encrypt(text_to_encrypt)
    decrypted_text = aes.decrypt(encrypted_text)

    ```
    
    """

    def __init__(self, key):
        self.block_size = AES.block_size
        self.key = hashlib.sha256(key.encode()).digest()

    def encrypt(self, plain_text):
        plain_text = self.__pad(plain_text)
        iv = Random.new().read(self.block_size)
        cipher = AES.new(self.key, AES.MODE_CBC, iv)
        encrypted_text = cipher.encrypt(plain_text.encode())
        iv_encrypted_text = iv + encrypted_text
        return b64encode(iv_encrypted_text, altchars=b'-:').decode("utf-8")

    def decrypt(self, encrypted_text):
        encrypted_text = b64decode(encrypted_text, altchars=b'-:')
        iv = encrypted_text[:self.block_size]
        cipher = AES.new(self.key, AES.MODE_CBC, iv)
        plain_text = cipher.decrypt(encrypted_text[self.block_size:]).decode("utf-8")
        return self.__unpad(plain_text)

    def __pad(self, plain_text):
        number_of_bytes_to_pad = self.block_size - len(plain_text) % self.block_size
        ascii_string = chr(number_of_bytes_to_pad)
        padding_str = number_of_bytes_to_pad * ascii_string
        padded_plain_text = plain_text + padding_str
        return padded_plain_text

    @staticmethod
    def __unpad(plain_text):
        last_character = plain_text[len(plain_text) - 1:]
        return plain_text[:-ord(last_character)]

Methods

def decrypt(self, encrypted_text)

Expand source code

def decrypt(self, encrypted_text):
    encrypted_text = b64decode(encrypted_text, altchars=b'-:')
    iv = encrypted_text[:self.block_size]
    cipher = AES.new(self.key, AES.MODE_CBC, iv)
    plain_text = cipher.decrypt(encrypted_text[self.block_size:]).decode("utf-8")
    return self.__unpad(plain_text)

def encrypt(self, plain_text)

Expand source code

def encrypt(self, plain_text):
    plain_text = self.__pad(plain_text)
    iv = Random.new().read(self.block_size)
    cipher = AES.new(self.key, AES.MODE_CBC, iv)
    encrypted_text = cipher.encrypt(plain_text.encode())
    iv_encrypted_text = iv + encrypted_text
    return b64encode(iv_encrypted_text, altchars=b'-:').decode("utf-8")