Rotating SMS API Keys Without Taking Login Offline

OTP security best practices cover bcrypt for codes and HTTPS for transport. This article focuses on a different secret: your SMS gateway API key—the credential that authorizes spend and sends. It complements, not duplicates, that guide.

Different From Hashing OTP Codes

User-facing OTP values are short-lived secrets you hash at rest. API keys are long-lived authentication to your provider. Leaked keys let an attacker send messages on your bill—see OTP fraud for attack patterns. Rotation reduces how long a stolen key works.

Dual-Key Cutover Pattern

If your dashboard allows creating a second key before revoking the old one, deploy in three steps: add new key to secrets store, roll pods or Lambdas to pick up new secret, verify traffic, revoke old key. Avoid big-bang restarts during peak login unless you run blue-green with both keys briefly valid.

Where Keys Live

Never commit keys to git. Use a secrets manager or encrypted CI variables. For local dev, document a fake key that points to mocks as in testing OTP in staging . Production keys should be readable only to the runtime role that calls your OTP API .

Leak Response Checklist

• Revoke the compromised key immediately in the provider dashboard.
• Issue a new key and deploy through your normal pipeline.
• Review recent sends for anomalous countries or volume spikes.
• Postmortem: how did the key leak—log, ticket, screenshot?

FAQ

See FAQ above.