Use of the info parameter in Hybrid Public Key Encryption I dont understand the use of the info parameter, what does &quot;to fold in identity information&quot; mean? What is the security benefit?

All the algorithms also take an info parameter that can be used to influence the generation of keys (e.g., to fold in identity information) [...]

https://www.ietf.org/archive/id/draft-irtf-cfrg-hpke-07.html#name-hybrid-public-key-encryptio
I dont understand the use of the info parameter, what does &quot;to fold in identity information&quot; mean?

It essentially is context information; that is, protection so that the ciphertext can't be reused in a different context.
Here is a simple example; suppose I encrypt a message to you, and fgrieu intercepts it.  Now, what fgrieu could do is forward that message to you and claim it was from him (he can't read it, however because I wrote it, he knows it must be good :-)
If that's all the system did, he'd succeed; there is no way that the message wasn't from fgrieu.
However, if we were to routinely put the sender's name in the info field (&quot;poncho&quot; in this case), well, fgrieu's attack wouldn't work - the only way you can decrypt the email is to include &quot;poncho&quot; in the info field during decryption, and you know that the specific email came from me (or some other poncho).