Protocol work looks tedious from the outside and turns out to be where the interesting failures live. The specification is short; the space of things implementers actually ship is not.
This piece walks through how we think about it at Paycux, what we have changed our minds about, and where the sharp edges are.
Understanding Single Logout
Understanding Single Logout deserves its own treatment. Version the assumption, not just the code. Write down what you expect from the peer, and make the failure loud when it stops being true, because the alternative is a connection that half works for six weeks.
Treat anything the other side sends as untrusted input until it has been through validation you wrote. Signature checks, issuer checks, audience checks and expiry checks are four separate decisions, and skipping any one of them is a real vulnerability rather than a theoretical one.
Single Logout with SAML
Single Logout with SAML is where this gets concrete. Treat anything the other side sends as untrusted input until it has been through validation you wrote. Signature checks, issuer checks, audience checks and expiry checks are four separate decisions, and skipping any one of them is a real vulnerability rather than a theoretical one.
Normalization is the whole job. Two providers can be perfectly compliant and still disagree about what a group membership is, whether a logout is meaningful, and which attribute carries the email address.
- Validate signature, issuer, audience and expiry as four separate checks
- Normalize provider attributes into one internal shape
- Fail loudly when a peer stops meeting a documented assumption
- Keep a fixture per provider so regressions surface in CI
Single Logout with OpenID Connect
That brings us to single logout with openid connect. Version the assumption, not just the code. Write down what you expect from the peer, and make the failure loud when it stops being true, because the alternative is a connection that half works for six weeks.
Normalization is the whole job. Two providers can be perfectly compliant and still disagree about what a group membership is, whether a logout is meaningful, and which attribute carries the email address.
Why is SLO important?
Consider why is slo important?. Treat anything the other side sends as untrusted input until it has been through validation you wrote. Signature checks, issuer checks, audience checks and expiry checks are four separate decisions, and skipping any one of them is a real vulnerability rather than a theoretical one.
Treat anything the other side sends as untrusted input until it has been through validation you wrote. Signature checks, issuer checks, audience checks and expiry checks are four separate decisions, and skipping any one of them is a real vulnerability rather than a theoretical one.
Normalization is the whole job.
Pain points of SLO
Pain points of SLO is where this gets concrete. Version the assumption, not just the code. Write down what you expect from the peer, and make the failure loud when it stops being true, because the alternative is a connection that half works for six weeks.
Treat anything the other side sends as untrusted input until it has been through validation you wrote. Signature checks, issuer checks, audience checks and expiry checks are four separate decisions, and skipping any one of them is a real vulnerability rather than a theoretical one.
Technical complexities
Technical complexities deserves its own treatment. Normalization is the whole job. Two providers can be perfectly compliant and still disagree about what a group membership is, whether a logout is meaningful, and which attribute carries the email address.
Normalization is the whole job. Two providers can be perfectly compliant and still disagree about what a group membership is, whether a logout is meaningful, and which attribute carries the email address.
Lack of standardization across SPs
That brings us to lack of standardization across sps. Normalization is the whole job. Two providers can be perfectly compliant and still disagree about what a group membership is, whether a logout is meaningful, and which attribute carries the email address.
Normalization is the whole job. Two providers can be perfectly compliant and still disagree about what a group membership is, whether a logout is meaningful, and which attribute carries the email address.
Where this leaves us
The pattern repeats across every system we have looked at: the hard part is not the mechanism, it is keeping the mechanism honest as the surrounding assumptions change.
If you are working through the same problem and want to compare notes, the docs cover the mechanics and the console shows the behaviour on your own data.
Everything here, already built
Sign-in, enterprise SSO, directory provisioning, roles and an audit trail behind one API.