I’m using Fernet to encrypt my data. Let’s assume that I have these three data:
data = [fernet.encrypt("Hello".encode()), fernet.encrypt("Stack".encode()), fernet.encrypt("Overflow".encode())]
After this operation, Python automatically converts bytes to string, and I’m writing them to a csv file. When I need to decrypt them like:
fernet.decrypt(data)
It gives me an error like you can only decrypt only bytes etc. I also checked that my data in the csv file is already bytes but string form.
b'gAAAAABiVUw5BzOkOv3VxlV5xa57Iaf0R4dzPbgsrnheAME8uYeslCZfTx9GeyRWe7l9VMM-gdDXiPZ4zsAXoXkG6T1dyXH6EztcqirrPhXX3YCt65_3xXvykVTDPdbEXs51cHvR-3HH'
>Solution :
An end-to-end usage example for encoding, writing to text, reading, and decoding.
The Fernet documentation can be referenced here.
from cryptography.fernet import Fernet
# Auto-generate a secret key.
key = Fernet.generate_key()
f = Fernet(key)
# Encode the string 'Hello' and encrypt.
encoded = f.encrypt('Hello'.encode())
This creates a bytestring (a bytes object) as:
b'gAAAAABiVVOOeO-hUG2QaKCVOyshntpbqVbxnexIVsFr7ttBGmKhHlDeM7jkTCjPPGphZxbh4D15X82pts3hKes12DjzwI8_jQ=='
Write, read and decrypt:
# Write the *decoded* encrypted string to a TXT file.
with open('/tmp/encoded.txt', 'w') as fh:
fh.write(encoded.decode())
# Read the encrypted string from TXT file.
with open('/tmp/encoded.txt') as fh:
encoded = fh.read()
# Encode the string, pass through fernet for decryption,
# and decode the bytes output.
f.decrypt(encoded.encode()).decode()
Output:
'Hello'