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Protocols22 December 2023·4 min read

SAML 2.0 vs SAML 1.1 - What’s the difference between the SAML versions?

It is easy to read a specification and conclude the problem is solved.

Paycux engineering

It is easy to read a specification and conclude the problem is solved. It is harder to sit with the twenty implementations that each read the same paragraph differently and still call themselves compliant.

This piece walks through how we think about it at Paycux, what we have changed our minds about, and where the sharp edges are.

Quick Overview: The differences between SAML 2.0 and SAML 1.1

Consider quick overview: the differences between saml 2.0 and saml 1.1. 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.

What is SAML 2.0?

Consider what is saml 2.0?. 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.

  • 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

Key Benefits of SAML 2.0

Key Benefits of SAML 2.0 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.

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.

What is SAML 1.1?

Consider what is saml 1.1?. 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.

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.

Key differences between SAML 2.0 vs SAML 1.1

That brings us to key differences between saml 2.0 vs saml 1.1. 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.

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.

Protocols

Protocols 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.

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.

Bindings

That brings us to bindings. 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.

Where this leaves us

If there is one thing worth taking away, it is that the expensive decisions are the ones made implicitly. Making them on purpose costs an afternoon.

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.

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