str Object has no attribute 'Encrypt'

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I made a program that generates a public key and another private key, serializes them and saves them in a .key. Dai tried to create another program to encrypt and decrypt a message with these two keys generated in the other program, how can I do this? 

from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import padding

#o que ira ser criptografado.
message = b"UMA CHAVE MUITO SECRETA"
#chave privada gerada em outro programa e salva em um arquivo .key
private_key ="""-----BEGIN ENCRYPTED PRIVATE KEY-----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gbsCapn0BEOpW+WIekda50yxUSagfLTdUzvMS4ZcxUW6vEdNuFygRSXkPStmKpsC
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Y71l4dDHPrHVL6KeBHW7Z3kUHGv2AfCYUQrvP0jp7VzgGHmLLcNx4Mtra4QQe798
Oqn3MJMiOGWyKx7md46NAfHwguRrQbQWBCEh5rL+GU/bVXthKEAgvU6hNCd9f0z0
sGsCR5/jeFyNHQ0L1JhsjpqBiYKrh9PZhO4eeKBh9Jnm+pstotG/7SyxBo83sDQb
sT8SniRqRkdnHi6Rv4RNNpfh5Obd6hGV7Mi4TdPmvCTc4WF32gUU0QGoXw0CvWtR
DnljEYWj199jwSdUrHeMjnjKtCJDt3+FoNVxM+TCC9zmMWq1Oj0FSu9CAZM5dlYZ
knO+sLo3K36ptfFbFofG9WmaElPIlRPdx0YMf32U8gRgKpZBZoztlEtjeqrf9rvP
0PrpUweJzVBfvt9q+TvG35TMa4IPUeVi0Od1dtk6pdPmMHlG7z1+LBaRMlm1wzj5
Qxc30xZPFOWCmsLUJah+oxovEFcyWeQ6rH7qufqzEYHLm876uxKGSKJSTwYk5Boi
4XsrVl9UUGjvh9XsnMnIGc/xSrTuNAW4qhLvrdcuPXf8
-----END ENCRYPTED PRIVATE KEY-----
"""
#chave publica gerada em outro programa e salva em um arquivo key.
public_key = """-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAxu6aLyNkusNci2aiIVoK
5Bc8JcwsBx5Rfq/S7u0OWRnQz+KXnJ+QEOTozP/ywzaubsuVSEr73dtkbrSvx/7K
mGg9qiqgR6f3pUOKt4d7FGV/HBwYcHaEI8albex9vTInjsT5YiLG0fppjckLvYrZ
xtjUcOsbOCYr7hUc1YgbyM5whbXbuCmC48KzAvEwIZnq1K0qqM5rea7y88a0Izr6
ADt6aGe/O8p13TSWbBeH+tufISSDBo2GN+KCWgYJ6heLcu7sS+9SvdxDwp+KaO0z
lWOocA+Tcpc3Zu5KDS/lIq1LZDAmjVIl6I4+8UvGDmhnIvAKHFroW1Ulg7TptBKz
pwIDAQAB
-----END PUBLIC KEY-----
"""
#criptografando
ciphertext = public_key.encrypt(
    message,
        padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA1()),
        algorithm=hashes.SHA1(),
        label=None
    )
)
print(ciphertext)
#descriptografando
normaltext = private_key.decrypt(
    ciphertext,
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA1()),
        algorithm=hashes.SHA1(),
        label=None
    )
)

print(normaltext)
python python-3.x cryptography

  • But public_key is, in fact, a str and not this method encrypt. What are you trying to do?

  • there is some way I can use the key created in another program that generated the key and use in this?

  • or how to put Encrypt method?

  • The question is, where do you want to call this encrypt. The first information you already have: It is not in str that you do it. I imagine you wanted to use something from the library cryptography, perhaps it was the case to give a read in the documentation.

  • Nathalia, spy on this one doc. Looks like the lib you’re using

1 answer

2


It’s missing code there - You try to call public_key.decrypt() but public_key is a str - a standard type already defined in python - and none str has the methods decrypt nor encrypt, so there’s one piece missing from your puzzle. I believe that these methods you want to call must be defined on another object in the encryption library you are using, and not on objects of the type str.

Look at this example I took from library documentation:

# ...
>>> from cryptography.fernet import Fernet
>>> key = Fernet.generate_key()
>>> f = Fernet(key)
>>> token = f.encrypt(b"my deep dark secret")
# ...

As you can see, he calls the method .encrypt() in f which is an instance of the class Fernet() and not in a str. He passes the cryptographic key to that class Fernet() what returns an object f that, yes, has the method encrypt().

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