Program Crashes when Serializing ed25519 and ed448 Private Keys with DER Encoding, PKCS8 Format, and Password "\x00"

[arunanshub]

Issue description

When ed25519 and ed448 private keys are serialized using DER encoding, PKCS8 format and \x00 as password, it causes the thread to panic and crashes the program.

Steps to reproduce bug

from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import ed448, ed25519

ed25519_priv_key = ed25519.Ed25519PrivateKey.generate()
ed25519_priv_key.private_bytes(
    serialization.Encoding.DER,
    serialization.PrivateFormat.PKCS8,
    serialization.BestAvailableEncryption(b"\x00"),
)

ed448_priv_key = ed448.Ed448PrivateKey.generate()
ed448_priv_key.private_bytes(
    serialization.Encoding.DER,
    serialization.PrivateFormat.PKCS8,
    serialization.BestAvailableEncryption(b"\x00"),
)

NOTE: using any other password does raise an error.

cryptography installation

cryptography is installed via poetry with version constraint >=35.0.0:

[tool.poetry.dependencies]
python = "^3.8"
cryptography = ">=35.0.0"

Required Version numbers

• pip: 23.0.1
• cffi: 1.15.1
• cryptography: 41.0.0
• setuptools: 67.8.0

[alex]

Can you please include the full output of the program? Was this something that previously worked?

[arunanshub]

Sure, here is the traceback:

thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: NulError(0, [0])', /github/home/.cargo/registry/src/index.crates.io-6f17d22bba15001f/openssl-0.10.53/src/pkey.rs:366:55
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Traceback (most recent call last):
  File "[...]/test.py", line 5, in <module>
    ed25519_priv_key.private_bytes(
pyo3_runtime.PanicException: called `Result::unwrap()` on an `Err` value: NulError(0, [0])

Was this something that previously worked?

Yes, it worked in cryptography v40.0.2.

[alex]

Ok, I see the problem. Thanks for the clear report.

[alex]

sfackler/rust-openssl#1941 is the first step to fixing.