SSH Public Key Parser

3.3.1 · active · verified Sun Apr 12

sshpubkeys is a Python library for parsing SSH public keys. It supports various key types (RSA, DSA, ECDSA, Ed25519) and can handle authorized_keys file formats, including options like 'command=' or 'no-port-forwarding'. The current version is 3.3.1, and it maintains an active, feature-driven release cadence.

Warnings

breaking Support for Python 2.6 and Python 3.3 was dropped.
Fix: Upgrade your Python environment to Python 3.4+ (preferably 3.6+).
breaking Handling of DSA keys changed; 'loose mode' no longer accepts non-standard DSA key lengths.
Fix: Ensure all DSA keys conform to standard lengths (e.g., 1024-bit). If you rely on non-standard lengths, you may need to regenerate or migrate keys.
breaking The internal ECDSA implementation dependency shifted from `ecdsa` to `cryptography`. While generally internal, direct interaction with `_key.ecdsa_key` or similar internal objects will break.
Fix: Refactor code to use only the public API of `SSHKey`. Avoid accessing internal, private attributes or methods that may rely on specific underlying cryptographic libraries.
gotcha Python 3.5 support was temporarily broken in versions immediately preceding `3.3.1`, despite earlier support.
Fix: If using Python 3.5, ensure you are on `sshpubkeys` version `3.3.1` or later for correct compatibility, or preferably, upgrade to a newer, actively supported Python version.
gotcha A typo `ed25516` was corrected to `ed25519` for the key type. While primarily an internal fix, users relying on string comparisons with the incorrect type might be affected.
Fix: Always use the `key_type` property and verify against the correct 'ed25519' string. Ensure your code doesn't implicitly rely on the old typo for string comparisons or type lookups.

Install

pip install sshpubkeys Install latest version

Imports

SSHKey
```
from sshpubkeys import SSHKey
```

InvalidKeyException

from sshpubkeys import InvalidKeyException

Quickstart

Initialize an SSHKey object from a public key string, retrieve its properties, and perform basic validation. Demonstrates handling of `InvalidKeyException`.

from sshpubkeys import SSHKey, InvalidKeyException
import os

# This is a dummy example key. Replace with a real key or load from a file.
# For actual use, avoid hardcoding keys directly in code.
# A real key might look like: 'ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCq2z/t... user@example.com'
example_public_key_string = os.environ.get(
    'SSH_PUBLIC_KEY', 
    'ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCw0Y1c/tFk9k/N... dummy_key@example.com'
)

try:
    key = SSHKey(example_public_key_string)
    print(f"Key type: {key.key_type}")
    print(f"Key length: {key.length}")
    print(f"Fingerprint (MD5): {key.hash_md5}")
    print(f"Fingerprint (SHA256): {key.hash_sha256}")
    print(f"Comment: {key.comment}")
    key.verify_length() # Ensures key length is standard for its type
    print("Key is valid and has standard length.")
except InvalidKeyException as e:
    print(f"Error parsing SSH key: {e}")
except Exception as e:
    print(f"An unexpected error occurred: {e}")

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