Подключение к Dropbear SSH с использованием файла ключа невозможно (в доступе отказано (открытый ключ))

Я использую свой домашний сервер (Ubuntu 20.04 LTS) с зашифрованным корнем и пытаюсь использовать dropbear в initramfs, чтобы иметь возможность удаленно разблокировать его во время загрузки. Чтобы настроить возможность удаленной разблокировки, я в основном следовал этому руководству: Как установить зашифрованный LUKS сервер Ubuntu 18.04.x ​​и включить удаленную разблокировку.

На моем MacBook я успешно создал пару ключей SSH:

      (base) myuser@myMBP ~ % ssh-keygen -t rsa -b 4096

После этого я добавляю вновь сгенерированный открытый ключ в /etc/dropbear-initramfs/authorized_keys:

      myuser@myserver:~$ cat /etc/dropbear-initramfs/authorized_keys 
no-port-forwarding,no-agent-forwarding,no-x11-forwarding,command=/bin/cryptroot-unlock ssh-rsa <here-goes-my-ssh-pubkey> myuser@myMBP.local

После этого бегmyuser@myserver:~$ sudo update-initramfs -c -k allвсе прошло нормально.

Однако попытка войти на SSH-сервер Dropbear не работает:

      (base) myuser@myMBP ~ % ssh -i ~/.ssh/id_rsa -o "HostKeyAlgorithms ssh-rsa" -p 9999 root@192.168.xxx.xxx -vvv
OpenSSH_8.6p1, LibreSSL 2.8.3
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: include /etc/ssh/ssh_config.d/* matched no files
debug1: /etc/ssh/ssh_config line 54: Applying options for *
debug2: resolve_canonicalize: hostname 192.168.xxx.xxx is address
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> '/Users/myuser/.ssh/known_hosts'
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> '/Users/myuser/.ssh/known_hosts2'
debug1: Authenticator provider $SSH_SK_PROVIDER did not resolve; disabling
debug3: ssh_connect_direct: entering
debug1: Connecting to 192.168.xxx.xxx [192.168.xxx.xxx] port 9999.
debug3: set_sock_tos: set socket 3 IP_TOS 0x48
debug1: Connection established.
debug1: identity file /Users/myuser/.ssh/id_rsa type 0
debug1: identity file /Users/myuser/.ssh/id_rsa-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.6
debug1: Remote protocol version 2.0, remote software version dropbear_2019.78
debug1: compat_banner: no match: dropbear_2019.78
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to 192.168.xxx.xxx:9999 as 'root'
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-c
debug2: host key algorithms: ssh-rsa
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com,zlib
debug2: compression stoc: none,zlib@openssh.com,zlib
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,kexguess2@matt.ucc.asn.au
debug2: host key algorithms: ecdsa-sha2-nistp256,ssh-rsa,ssh-dss
debug2: ciphers ctos: aes128-ctr,aes256-ctr,aes128-cbc,aes256-cbc,3des-ctr,3des-cbc
debug2: ciphers stoc: aes128-ctr,aes256-ctr,aes128-cbc,aes256-cbc,3des-ctr,3des-cbc
debug2: MACs ctos: hmac-sha1-96,hmac-sha1,hmac-sha2-256
debug2: MACs stoc: hmac-sha1-96,hmac-sha1,hmac-sha2-256
debug2: compression ctos: zlib@openssh.com,none
debug2: compression stoc: zlib@openssh.com,none
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ssh-rsa
debug1: kex: server->client cipher: aes128-ctr MAC: hmac-sha2-256 compression: none
debug1: kex: client->server cipher: aes128-ctr MAC: hmac-sha2-256 compression: none
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: SSH2_MSG_KEX_ECDH_REPLY received
debug1: Server host key: ssh-rsa SHA256:vdFXJflh1ltg2QQ6A8S5qnjtPBtKR3h6l548DAh6Hwk
debug3: put_host_port: [192.168.xxx.xxx]:9999
debug3: put_host_port: [192.168.xxx.xxx]:9999
debug3: record_hostkey: found key type RSA in file /Users/myuser/.ssh/known_hosts:4
debug3: load_hostkeys_file: loaded 1 keys from [192.168.xxx.xxx]:9999
debug1: load_hostkeys: fopen /Users/myuser/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug1: Host '[192.168.xxx.xxx]:9999' is known and matches the RSA host key.
debug1: Found key in /Users/myuser/.ssh/known_hosts:4
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey out after 4294967296 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey in after 4294967296 blocks
debug1: Will attempt key: /Users/myuser/.ssh/id_rsa RSA SHA256:XizaS2UPC7m5C37NwgUVI8uPvLBzLINvRSBnpKGkzPE explicit
debug2: pubkey_prepare: done
debug3: send packet: type 5
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey
debug3: start over, passed a different list publickey
debug3: preferred publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering public key: /Users/myuser/.ssh/id_rsa RSA SHA256:XizaS2UPC7m5C37NwgUVI8uPvLBzLINvRSBnpKGkzPE explicit
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
root@192.168.xxx.xxx: Permission denied (publickey).

Почему, пытаясь решить эту проблему, я наткнулся на следующую ошибку Ubuntu: перехватчик initramfs Dropbear создает файл авторизованных ключей в недопустимой папке, но применение предложенного обходного пути в моем случае не помогло...

Есть ли у вас какие-либо идеи, что может пойти не так?

Заранее спасибо, песочный человек