"Invalid Session Participant" - incorrect session index exception

Thanks for the fantastic library, it's really helping out with what I'm trying to build.

I'm having an issue implementing logout from my currently in development SP. I can log in successfully, but when I go to log out using the slo endpoint with redirect, I get the following error:

Error: Invalid Session Participant
    at c:\Users\jhubers\Documents\Code\saml-idp\node_modules\samlp\lib\logout.js:181:65
    at SessionParticipants.get (c:\Users\jhubers\Documents\Code\saml-idp\node_modules\samlp\lib\sessionParticipants\index.js:32:20)
    at c:\Users\jhubers\Documents\Code\saml-idp\node_modules\samlp\lib\logout.js:178:39
    at c:\Users\jhubers\Documents\Code\saml-idp\node_modules\samlp\lib\logout.js:295:5
    at c:\Users\jhubers\Documents\Code\saml-idp\node_modules\samlp\lib\utils.js:121:20
    at c:\Users\jhubers\Documents\Code\saml-idp\node_modules\samlp\lib\utils.js:76:16
    at c:\Users\jhubers\Documents\Code\saml-idp\node_modules\samlp\lib\logout.js:161:38
    at SessionParticipants.get (c:\Users\jhubers\Documents\Code\saml-idp\node_modules\samlp\lib\sessionParticipants\index.js:32:20)
    at Object.getCredentials (c:\Users\jhubers\Documents\Code\saml-idp\node_modules\samlp\lib\logout.js:159:41)
    at configureSigningCredentials (c:\Users\jhubers\Documents\Code\saml-idp\node_modules\samlp\lib\utils.js:74:13)

Looking at where the line is failing in the samlp library I see the following:

...
          options.sessionParticipants.get(requestData.issuer, requestData.sessionIndex, requestData.nameId, function (err, session) {
            if (err) { return next(err); }
            if (!session && !options.destination) { return next(new Error('Invalid Session Participant')); }
...

I have debugged'ed and looked at what values options.sessionParticipants has and what values requestData has.

The requestData.sessionIndex is misaligned with what is in options.sessionParticipants[...].sessionIndex so a user is never found.

I believe there is a missing or incorrect getParticipant in saml-idp with hashing the sessionIndex.

I say this because the samlp.sessionParticipants[...].sessionIndex is the hashed value of the requestData.sessionIndex that I am looking up.

For example,

I log in with the following information:

id:"identifier_1"
issuer:"https://myapp.org"
nameId:"saml.jackson@example.com"
nameIdFormat:"urn:oasis:names:tc:SAML:2.0:nameid-format:persistent"
sessionIndex:"1"

When I go to log out, I see that samlp sessionParticipants has the following participants:

nameId:"saml.jackson@example.com"
nameIdFormat:"urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress"
serviceProviderId:"https://www.okta.com/saml2/service-provider/spf5aFRRXFGIMAYXQPNV"
serviceProviderLogoutURL:"/saml/slo"
sessionIndex:"1652171193"

And the requestData.sessionIndex is 1

mcguinness / saml-idp

"Invalid Session Participant" - incorrect session index exception #60