Following step-by-step the wiki to encrypt an usb disk, I get:
Preliminary steps to verify that all packages are present and updated (kmod-crypto-iv is not present anymore in repositories):
# opkg install kmod-crypto-ecb kmod-crypto-xts kmod-crypto-iv kmod-crypto-misc kmod-crypto-user cryptsetup
Package kmod-crypto-ecb (5.4.188-1) installed in root is up to date.
Package kmod-crypto-xts (5.4.188-1) installed in root is up to date.
Unknown package 'kmod-crypto-iv'.
Package kmod-crypto-misc (5.4.188-1) installed in root is up to date.
Package kmod-crypto-user (5.4.188-1) installed in root is up to date.
Package cryptsetup (2.4.3-1) installed in root is up to date.
Collected errors:
* opkg_install_cmd: Cannot install package kmod-crypto-iv.
root@OpenWrt:/# opkg install kmod-fs-ext4 e2fsprogs
Package kmod-fs-ext4 (5.4.188-1) installed in root is up to date.
Package e2fsprogs (1.45.6-2) installed in root is up to date.
Then:
root@OpenWrt:/# cryptsetup luksFormat /dev/sdb1
WARNING: Device /dev/sdb1 already contains a 'vfat' superblock signature.
WARNING!
========
This will overwrite data on /dev/sdb1 irrevocably.
Are you sure? (Type 'yes' in capital letters): YES
Enter passphrase for /dev/sdb1:
Verify passphrase:
Cannot initialize crypto backend.
Failed to set pbkdf parameters.
And obviously I'm unable to continue.
The same happens if I try to encrypt a file (as described in this thread).
Since you can't replicate, I suppose it is a bug for this specific platform (MT7621) or model (linksys ea7300).
I will not open a ticket because yesterday I upgraded to 22.03.0-rc4 and luckily the issue disappeared.
Thank you anyway.
P.S.: where can I open a ticket for a specific platform not related to any package? I refer to this.