69 lines
2.8 KiB
Python
69 lines
2.8 KiB
Python
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# third party imports
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import bcrypt
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from cryptography.fernet import Fernet
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class PasswordEncoder(Fernet):
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"""This class is responsible for defining the encryption function for password encoding in the application and the
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provision of a class method that can be used to define the static key attribute at the application's entry point.
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:cvar key: a URL-safe base64-encoded 32-byte
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:type key: bytes
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"""
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key = None
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@classmethod
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def set_key(cls, key: bytes):
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"""This method sets the value of the static key attribute to make it accessible to all subsequent instances of
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the class once defined.
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:param key: key: a URL-safe base64-encoded 32-byte
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:type key: bytes
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"""
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cls.key = key
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def encrypt(self, ciphertext: bytes):
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"""This overloads the encrypt function of the Fernet class
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:param ciphertext: The data to be encrypted.
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:type ciphertext: bytes
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:return: A fernet token (A set of bytes representing the hashed value succeeding the encryption)
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:rtype: bytes
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"""
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return super(PasswordEncoder, self).encrypt(ciphertext)
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def create_password_hash(password):
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"""This method encrypts a password value using a pre-set pepper and an appended salt. Documentation is brief since
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symmetric encryption using a unique key (pepper) and salted passwords before hashing is well documented.
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N/B: Fernet encryption requires the unique key to be a URL-safe base64-encoded 32-byte key.
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https://cryptography.io/en/latest/fernet/
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:param password: A password value
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:type password: str
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:raises ValueError: if a key whose length length is less than 32 bytes.
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:raises binascii.Error: if base64 key is invalid or corrupted.
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:return: A fernet token (A set of bytes representing the hashed value succeeding the encryption)
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:rtype: str
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"""
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fernet = PasswordEncoder(PasswordEncoder.key)
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return fernet.encrypt(bcrypt.hashpw(password.encode(), bcrypt.gensalt())).decode()
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def check_password_hash(password, hashed_password):
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"""This method ascertains a password's validity by hashing the provided password value using the original pepper and
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compares the resultant fernet signature to the one persisted in the db for a given user.
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:param password: A password value
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:type password: str
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:param hashed_password: A hash for a user's password value
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:type hashed_password: str
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:raises ValueError: if a key whose length length is less than 32 bytes.
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:raises binascii.Error: if base64 key is invalid or corrupted.
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:return: Password validity
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:rtype: boolean
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"""
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fernet = PasswordEncoder(PasswordEncoder.key)
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hashed_password = fernet.decrypt(hashed_password.encode())
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return bcrypt.checkpw(password.encode(), hashed_password)
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