LUKS: how is decryption done when using the --use-random option?

Question

linux

It turns out that all data is decrypted by the key generated by /dev/urandom'om/ /dev/random'om?
When I encrypt data with a password, then all data is encrypted with a passphrase, right?
Then why do we need a "random" key and what is the algorithm? Is a random key written somewhere, and is the data encrypted under this random key + password?

Answer 1

There is a double key used.
A random encryption key is generated for the drive. This key itself is encrypted with a passphrase and stored in encrypted form in the LUKS partition header.
Thus, the possibility of decrypting a disk with different passwords is implemented (for example, each user has his own password). For each password, a key is stored (one for all passwords) encrypted with this password. In total in my opinion 8 records can be. To remove the password, just remove the entry with the encrypted key.