What are you trying to achieve ?   If you have access to the local X3 instance, why not check your login name/password by logging into X3 itself ?     You can execute ANY webservice call as it will need a valid username/password to succeed

I'm developping an external app.  In this app, the user must log via sage X3 user / password to confirm access.

After log, the app call a soap web service X3 i created. This service complete a trace log, get some stuffs and must check the user/password X3 to confirm the access. I can check the ID with a read on AUTILIS but not the crypted password.

Sorry I'm still a little confused, so the username and password entered by the user are used by the webservice call, or is this a static usernamepassword which is differenet ?

If you use the username and password from the user themselves, then X3 will do the validation for you, there is no need to try and manually reauthenticate.    

Also, the AUTILIS is the folder level username, which may be different from the username they login as

The web service is set and used just to etablsih the communication between the app and sage X3.

The user doesn't access to the settings of web service and doesn't set the aliaspool.

The first screen of the app is a login. the user input this id and password.

The web service check if the user/password is OK. It's this point i want to do.

The web service is set and used just to etablsih the communication between the app and sage X3.

The user doesn't access to the settings of web service and doesn't set the aliaspool.

The first screen of the app is a login. the user input this id and password.

The web service check if the user/password is OK. It's this point i want to do.

When you make a SOAP request to X3,  you need to provide the username/password for a valid X3 user. This goes into the SOAP request as a "Authorization" header.  How are you handling this currently ?   This is what I think you should be using the username/password of the user for

Solved, I found what i need. This is the solution

Read [AUS]LOGIN=toupper(vireblc(USERCODE,0))
Call CTLPAS(vireblc(PASSWORD,0), OK) From GESUSER