SSH Private Key (OpenSSH Format) Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching ssh private key (openssh format), ported and verified for JavaScript. 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 JavaScript project — whether you're validating in an Express middleware, a Next.js API route, or a client-side form.

Javascript Implementation

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

const sshPrivateKeyOpensshFormatRegex = /-----BEGIN OPENSSH PRIVATE KEY-----[\r\n]+(?:[A-Za-z0-9+\/=\r\n]{1,80}[\r\n]+)*-----END OPENSSH PRIVATE KEY-----/;

function validateSshPrivateKeyOpensshFormat(input: string): boolean {
  return sshPrivateKeyOpensshFormatRegex.test(input);
}

// Example
console.log(validateSshPrivateKeyOpensshFormat("-----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 JavaScript developers because especially critical in long-running Node.js event loops where a ReDoS vulnerability can block the entire process. 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.