The vanilla "secure pastebin" is simply an insecure pastebin served over HTTPS.
Better, actually-trying-to-be-secure pastebin implementations will encrypt the data with JS before sending it to the server, and later decrypt it with a key that's embedded in the link's URL fragment (which the server never sees).
The security evolution here is that both the ciphertext and the code for the webpage to decrypt it are stored on IPFS, which is a content-addressed filesystem.
Thus, so long as you access pastes through a trusted (ie, local) IPFS note, the hardbin server operator can't insert code on the webpage after-the-fact to exfiltrate the key or plaintext back to them.
Better, actually-trying-to-be-secure pastebin implementations will encrypt the data with JS before sending it to the server, and later decrypt it with a key that's embedded in the link's URL fragment (which the server never sees).
The security evolution here is that both the ciphertext and the code for the webpage to decrypt it are stored on IPFS, which is a content-addressed filesystem.
Thus, so long as you access pastes through a trusted (ie, local) IPFS note, the hardbin server operator can't insert code on the webpage after-the-fact to exfiltrate the key or plaintext back to them.