SSH Private Key (OpenSSH Format) Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching ssh private key (openssh format), ported and verified for Python. In security-sensitive code, using an unverified regex can open the door to both false positives and denial-of-service attacks. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# SSH Private Key (OpenSSH Format)
# ReDoS-safe | RegexVault — Security > Certificates & PKI

import re

ssh_private_key_openssh_format_pattern = re.compile(r'-----BEGIN OPENSSH PRIVATE KEY-----[\r\n]+(?:[A-Za-z0-9+/=\r\n]{1,80}[\r\n]+)*-----END OPENSSH PRIVATE KEY-----')

def validate_ssh_private_key_openssh_format(value: str) -> bool:
    return bool(ssh_private_key_openssh_format_pattern.fullmatch(value))

# Example
print(validate_ssh_private_key_openssh_format("-----BEGIN OPENSSH PRIVATE KEY-----
b3BlbnNzaC1rZXktdjEAAAAAAAAA
-----END OPENSSH PRIVATE KEY-----"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Security > Certificates & PKI category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

OpenSSH private key format (openssh-key-v1) is the default since OpenSSH 6.5 (2014). Unlike PEM RSA keys, this format includes key type metadata and may be passphrase-protected. The base64 payload includes the key type, public key, and encrypted private key.