"Fernet" python encoding gives me the following error: ValueError: Fernet key must be 32 url-safe base64-encoded bytes

Question

I have the following code that takes the encrypted keys from a .bin file

from cryptography.fernet import Fernet
    def C(i):
      f=open('/home/credentials.bin',"rb")
      e=f.read()
      e=e.split("\n")
      e2=e[-2]
      d = Fernet(e2)
      c = e[i]
      t = (d.decrypt(c))
      s= bytes(t).decode("utf-8")
      f.close()
      return str(s)
    
    print(C(0))

trying to print the decrypted key gives me the following error:

"Fernet key must be 32 url-safe base64-encoded bytes."

ValueError: Fernet key must be 32 url-safe base64-encoded bytes.

credentials.bin continent `

"gAAAAABeTAKV_odfhx3i6BhiaXeEDdxvG3eDdployKspvIcnm87zXd94fklNm1mMVkTlN6UUehyw0VzgNU1mj0Zlzi6yNynmOA=="

`

I appreciate your help

Please, check [ask]. Post full traceback you get. As a side note - use descriptive names, not cryptic, one-letter names. — buran, Jun 17 '22 at 18:41
Thanks for the observation edit the question adding the content of the bin file which contains the encrypted key — Cristian Andres Gil Vlla, Jun 17 '22 at 19:34
You code should error before that. You are trying to split a bytes object with a string in `e = e.split('\n')` — Alexander, Jun 17 '22 at 20:00

score 0 · Accepted Answer · answered Jun 17 '22 at 20:25

Your key is too long for a Fernet key: it is:

len("gAAAAABeTAKV_odfhx3i6BhiaXeEDdxvG3eDdployKspvIcnm87zXd94fklNm1mMVkTlN6UUehyw0VzgNU1mj0Zlzi6yNynmOA==")

output:

whereas fernet keys are:

len(Fernet.generate_key())

output:

The only way it works with your key is if you cut off the first part but I am pretty sure this is not how it was intended

Fernet("gAAAAABeTAKV_odfhx3i6BhiaXeEDdxvG3eDdployKspvIcnm87zXd94fklNm1mMVkTlN6UUehyw0VzgNU1mj0Zlzi6yNynmOA=="[-45:-1])

output:

<cryptography.fernet.Fernet object at 0x7feb65b5bf10>

I think you have the wrong key here, or it is not a Fernet key.

"Fernet" python encoding gives me the following error: ValueError: Fernet key must be 32 url-safe base64-encoded bytes

1 Answers1