SSH Public Key Regex for Go

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching ssh public key, ported and verified for Go. 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 Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// SSH Public Key
// ReDoS-safe | RegexVault — Security > Certificates & PKI

package validation

import "regexp"

var sshPublicKeyRe = regexp.MustCompile(`^(ssh-rsa|ssh-ed25519|ssh-ecdsa|ecdsa-sha2-nistp256|ecdsa-sha2-nistp384|ecdsa-sha2-nistp521|sk-ssh-ed25519@openssh\.com|sk-ecdsa-sha2-nistp256@openssh\.com)\s+([A-Za-z0-9+/]{20,800}(?:={0,3}))(?:\s+(.+))?$`)

func ValidateSshPublicKey(s string) bool {
    return sshPublicKeyRe.MatchString(s)
}

// Example
// fmt.Println(ValidateSshPublicKey("ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOMqqnkVzrm0SdG6UOoqKLsabgH5C9okWi0dh2l9GKJl user@host")) // 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 Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. 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

Capture groups: 1=key type, 2=base64 key material, 3=comment (optional, usually user@host). Supported types: RSA (deprecated), Ed25519 (preferred), ECDSA (nistp256/384/521), SK (FIDO2 hardware key variants). Prefer Ed25519 for new SSH keys.