Transient keys are short-lived keys. For example, if you need to do a key agreement, you encrypt with the agreed key, and then throw away the agreed key. A benefit of such a key is that no other user/app can see a transient key, only its creator can see it while the session is active.
Transient keys live in the Fortanix DSM session, so they die after the session expires or is terminated.
Fortanix Data Security Manager (DSM) is the world’s first cloud service secured with Intel® SGX. With Fortanix DSM, you can securely generate, store, and use cryptographic keys and certificates, as well as other secrets such as passwords, API keys, tokens, or any blob of data. Your business-critical applications and containers can integrate with Fortanix DSM using legacy cryptographic interfaces (PKCS#11, CNG, and JCE) or using the native Fortanix DSM RESTful interface.