Why should each payment service have its own credentials?

Each payment service should have its own credentials because shared secrets make a leak impossible to trace and widen what an attacker can reach. Separate credentials give you a clear audit trail, narrower permissions, and the ability to revoke one service without taking down the others.

The problem with shared secrets

Early in a startup it is normal for the checkout service, the payout worker and the reporting job to use the same database password and the same payment provider key. It is quick and it works.

The OWASP Secrets Management cheat sheet describes the cost. It notes that services often share the same secrets, which makes identifying the source of a compromise or leak challenging. If a shared key shows up in a paste site, which of five services leaked it? You cannot tell from the key.

What separate credentials give you

The access control point is explicit in the OWASP text: engineers should not have access to all secrets, and least privilege applies. A secrets system needs fine-grained controls on each object so a payout worker can read its own database role but not the checkout service's.

How to split them

1. List every secret in use and every service that reads it. A spreadsheet is enough for a first pass.
2. For each shared secret, create one new credential per consuming service.
3. Give each new credential the smallest set of permissions that service needs. A reporting job may need read access to a replica and nothing else.
4. Name the credentials after the service and environment so logs are readable.
5. Roll services over one at a time, watching for errors.
6. Revoke the old shared credential when the last consumer has moved. Do not leave it valid.

Step 6 matters. A retired credential that still works is a standing risk with no owner.

Make attribution part of the design

OWASP asks that CI/CD tooling use designated service accounts that can operate within the scope of the secrets they need, and that each pipeline run be attributable to whoever defined or triggered the job. The same logic applies to runtime services. If your audit log records the requesting service and role, you can answer investigators quickly.

OWASP also lists what to audit: who requested a secret, for which system and role, whether the request was approved, and when it was used. Per-service identities are what make those entries meaningful.

Dynamic credentials make this cheaper

Creating dozens of static credentials sounds like more rotation work. The guidance suggests dynamic secrets where possible: an application requests database credentials at start up and receives new ones for that session, with a short lease. That reduces credential reuse and removes much of the manual upkeep.

Note the caveat in the same source. Restarting an application does not revoke stolen credentials. They stay usable until the backing service expires or revokes them, so set short leases and revoke when no longer needed.

Common objections

• "We have just three services." That is a good time to split, before ten more are added.
• "It adds operational overhead." It does, a little, and it pays back the first time you investigate an alert.
• "Our provider gives us a single API key." Ask whether it supports restricted or scoped keys, and put the key behind a single internal service so others call that service instead of holding the key.

Where Safeguard fits

Safeguard does not store secrets. Its agent identity feature and asset discovery can help you see which automated actors and services exist in your estate, and policies can enforce review rules on changes that touch them. A free scan is available at gold.safeguard.sh/scan.

Quick check

Sources

• OWASP Secrets Management Cheat Sheet

Last reviewed: 19 October 2026.