Password Policy Strength Check Regex for Go

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching password policy strength check, 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

// Password Policy Strength Check
// ReDoS-safe | RegexVault — Security > Password Formats

package validation

import "regexp"

var passwordPolicyStrengthCheckRe = regexp.MustCompile(`^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[!@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/?~`])(?!.*\s).{12,128}$`)

func ValidatePasswordPolicyStrengthCheck(s string) bool {
    return passwordPolicyStrengthCheckRe.MatchString(s)
}

// Example
// fmt.Println(ValidatePasswordPolicyStrengthCheck("Correct!Horse#Battery9")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Security > Password Formats category and is provided for complex validation requirements. 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

NIST SP 800-63b (2017) de-emphasized complexity rules in favor of length and breach database checking. This pattern implements the more traditional complexity approach. Minimum 12 characters is NIST-aligned. 128-char maximum prevents DoS via extremely long inputs.