PEM Private Key Block Regex for Go

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching pem private key block, 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

// PEM Private Key Block
// ReDoS-safe | RegexVault — Security > Certificates & PKI

package validation

import "regexp"

var pemPrivateKeyBlockRe = regexp.MustCompile(`-----BEGIN (?:RSA |EC |DSA |OPENSSH )?PRIVATE KEY-----[\r\n]+(?:[A-Za-z0-9+/=\r\n]{1,80}[\r\n]+)*-----END (?:RSA |EC |DSA |OPENSSH )?PRIVATE KEY-----`)

func ValidatePemPrivateKeyBlock(s string) bool {
    return pemPrivateKeyBlockRe.MatchString(s)
}

// Example
// fmt.Println(ValidatePemPrivateKeyBlock("-----BEGIN PRIVATE KEY-----
MIIEvAIBADANBgk=
-----END 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 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

CRITICAL detection pattern. Key type headers: 'PRIVATE KEY' (PKCS#8, unencrypted), 'RSA PRIVATE KEY' (PKCS#1, legacy OpenSSL), 'EC PRIVATE KEY' (SEC1), 'OPENSSH PRIVATE KEY' (SSH private keys). Encrypted private keys have 'ENCRYPTED PRIVATE KEY' header.