OAuth 2.0 Authorization Code Regex for Go

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching oauth 2.0 authorization code, 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

// OAuth 2.0 Authorization Code
// ReDoS-safe | RegexVault — Security > OAuth & OIDC

package validation

import "regexp"

var oauth20AuthorizationCodeRe = regexp.MustCompile(`^[A-Za-z0-9\-/_]{20,64}$`)

func ValidateOauth20AuthorizationCode(s string) bool {
    return oauth20AuthorizationCodeRe.MatchString(s)
}

// Example
// fmt.Println(ValidateOauth20AuthorizationCode("4/0AY0e-g7aBcDeFgHiJkLmNoPqRsTuVwXyZ01")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Security > OAuth & OIDC 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

Authorization codes are single-use and short-lived (typically 5-10 minutes). RFC 6749 does not specify the format — implementation-specific. Codes appear in the redirect URI as ?code=VALUE and must be exchanged immediately for an access token.