Unable to create an encrypted disk on OpenWrt 21.02

My system specifications:

Hostname OpenWrt
Model Linksys EA7300 v2
Architecture MediaTek MT7621 ver:1 eco:3
Target Platform ramips/mt7621
Firmware Version OpenWrt 21.02.3 r16554-1d4dea6d4f / LuCI openwrt-21.02 branch git-22.083.69138-0a0ce2a
Kernel Version 5.4.188

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).

What's the issue?

Is there something wrong with this model?

# cryptsetup benchmark
# Tests are approximate using memory only (no storage IO).
Cannot initialize crypto backend.
PBKDF2-sha1          N/A
Cannot initialize crypto backend.
PBKDF2-sha256        N/A
Cannot initialize crypto backend.
PBKDF2-sha512        N/A
Cannot initialize crypto backend.
PBKDF2-ripemd160     N/A
Cannot initialize crypto backend.
PBKDF2-whirlpool     N/A
Cannot initialize crypto backend.
argon2i    N/A
Cannot initialize crypto backend.
argon2id   N/A
Cannot initialize crypto backend.
#     Algorithm |       Key |      Encryption |      Decryption
        aes-cbc        128b               N/A               N/A
Cannot initialize crypto backend.
    serpent-cbc        128b               N/A               N/A
Cannot initialize crypto backend.
    twofish-cbc        128b               N/A               N/A
Cannot initialize crypto backend.
        aes-cbc        256b               N/A               N/A
Cannot initialize crypto backend.
    serpent-cbc        256b               N/A               N/A
Cannot initialize crypto backend.
    twofish-cbc        256b               N/A               N/A
Cannot initialize crypto backend.
        aes-xts        256b               N/A               N/A
Cannot initialize crypto backend.
    serpent-xts        256b               N/A               N/A
Cannot initialize crypto backend.
    twofish-xts        256b               N/A               N/A
Cannot initialize crypto backend.
        aes-xts        512b               N/A               N/A
Cannot initialize crypto backend.
    serpent-xts        512b               N/A               N/A
Cannot initialize crypto backend.
    twofish-xts        512b               N/A               N/A

Device /dev/sdb1 already contains a vfat superblock

Did you install vfat support?

kmod-fs-vfat

Or you could just format it to ext4

Yes. But that is not a problem. As I have written, even if I use another fs the error is the same.
It seems to me that there is a bug in the firmware.

I hear you, but I can't replicate your experience on any current release or snapshot I have built (19.07, 21.02.2, 21.02.3)

I think your next step is to raise an issue on https://github.com/openwrt/packages

You can find the maintainer and other relevant info in the Makefile https://github.com/openwrt/packages/blob/master/utils/cryptsetup/Makefile

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.

Glad it worked out.