---
title: "How do I generate and use PSK with TLS v1.3 in NanoSSL?"
source_url: https://dev.digicert.com/trustcore-sdk/nanossl/faqs/how-do-i-generate-and-use-psk-with-tls-v-1-3-in-nanossl.html
---

**Question:** How do I generate and use PSK in TLS v1.3 in NanoSSL?

**Answer:** To enable generation and use of PSK in TLS v1.3:

1. Request a session ticket in the new connection.
   ```c
   SSL_ioctl(connectionInstance, SSL_REQUEST_SESSION_TICKET, &requestTicket)
   ```
   where `requestTicket=1`.
2. Define and register a callback to save the PSK.
   ```c
   SSL_setClientSavePSKCallback(sbyte4 connectionInstance, sbyte4 (*cb) (sbyte4 connectionInstance, sbyte* ServerInfo, ubyte4 serverInfoLen, void *userData, ubyte *pPsk, ubyte4 pskLen))
   ```
3. For subsequent connections, use the saved PSK to establish a connection:
      - Set the PSK key exchange modes.
   SSL_ioctl(connectionInstance, SSL_PSK_KEY_EXCHANGE_MODE, &pskMode)
      - Define and register a callback to retrieve the PSK.
   SSL_CLIENT_setRetrievePSKCallback(sbyte4 connectionInstance, sbyte4 (*cb) (sbyte4 connectionInstance, sbyte* ServerInfo, ubyte4 serverInfoLen, void *userData, void **ppPSKs, ubyte2 *pNumPSKs,ubyte* selectedIndex, intBoolean *pFreeMemory)