> For the complete documentation index, see [llms.txt](https://docs.editran.onesait.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.editran.onesait.com/documentacion-editran/ibm-editran-v5.3-iseries-en/gestor-de-claves/appendix/key-exchange-application.md).
# Key exchange application
The application is proposed **TELEGC** to exchange keys (it is not mandatory; it can even be one application for one direction and another for the other).
If TELEGC is used, the presentation session and the associated transmission session are defined at both ends.
In this application, encryption can be used, but the sent-received keys are already encrypted, so its use is not very useful.
If TELEGC is used in both directions, different processes will occur:
* PROCESS 1- The local end issues a local key (before issuance and after issuance). The remote end receives it (after reception + before issuing the confirmation).
* PROCESS 2- The remote end issues the confirmation that it has processed it (after issuance). The local end receives it (after reception)
* PROCESS 3- The remote end issues a remote key (before issuance and after issuance). The local end receives it (after reception + before issuing the confirmation).
* PROCESS 4- The local end issues the confirmation that it has processed it (after issuance). The local end receives it (after reception).
* PROCESS 5- Additionally, each time RSA keys (private and public) are generated, although they are not transmitted to the remote side, the procedure specified in the Key Management profile is triggered.
The session profile would be as follows:
There are some post-reception user programs, which depending on what is being done, one or another is used.
Post-reception user program used in the REMOTE-KEY-RSA reception sessions.
* **U4PGCR01**
When the key is received, upon downloading it, it calls the PGCRCVR01 program with Function = '01' to load the Confirmation and activate the received key
* **U4PGCR02**
Post-reception user program used in the sending sessions of LOCAL-KEY-RSA.
When the Confirmation is received, upon downloading it, it calls the PGCRCVR02 program to activate the sent key
* **U4PGCR03**
Post-reception user program used in the REMOTE-KEY-RSA reception sessions.
When the key is received, upon downloading it, it calls the PGCRCVR01 program with Function = '03' to send the Confirmation and activate the received key
* **U4PGCD01**
Post-reception user program used in the REMOTE-KEY-DES reception sessions.
When the key is received, upon downloading it, it calls the PGCRCVD01 program with Function = 01 to load the Confirmation and activate the received key
* U4PGCD02
Post-reception user program used in the sending sessions of LOCAL-KEY-DES.
When the Confirmation is received, upon downloading it, it calls the PGCRCVD02 program to activate the sent key
* **U4PGCD03**
Post-reception user program used in the REMOTE-KEY-DES reception sessions.
When the key is received, upon downloading it, it calls the PGCRCVD01 program with Function = '03' to send the Confirmation and activate the received key
* **PUSUGC52**
**Post-reception user program, common to all options, of editran/gc 52.**
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