Why encryption is implemented this way?

[pfrankw]

Hi,

I've recently come across JuiceFS, which seems a very promising distributed filesystem.

However, since I am a security professional, I got interested in reading the "Data Encryption" page and can't understand why there is the presence of a "RSA private key" involved in the encryption process.

Question 1:
Generating a symmetric key for each block/object and then encrypting it with a master symmetric key, derived from a user passphrase, is common practice in the industry. Why in this case there is involved a RSA key?

Question 2:
If question 1 is replied, then why is the encrypting RSA key a private one? Private keys should be only used for signing, since decryption would happen by using public keys, which is not good nor common. Is this a typo?

Thank you