Ubuntu 16.04 and LUKS all partition

Question

I need to move old system (/dev/sda). Ubuntu 16.04 is LUKS partition. I would like to move the system (on /dev/sdb) so that all partitions (including /boot) are encrypted.

I have already copied the system to a new disk. Now I would like to encrypt boot partitions

$ lsblk 
NAME MAY: MIN RM SIZE RO TYPE MOUNTPOINT 
sda 8: 0 0 10G 0 disk 
├─sda1 8: 1 0 500M 0 part /boot 
├─sda2 8: 2 0 1K 0 part 
└─sda5 8: 5 0 9.5G 0 part 
  └─lvm 252: 0 0 9.5G 0 crypt 
    ├─MDISK-swap 252: 1 0 500M 0 lvm [SWAP] 
    └─MDISK-root 252: 2 0 9G 0 lvm / 
sr0 11: 0 1 1024M 0 rom –

=================

I'm asking further :)

I created partitions /boot and encrypted. The system starts, but I need to enter the password for the boot twice. Any idea ?

root@ubuntusrv2tmp:~# lsblk 
NAME             MAJ:MIN RM  SIZE RO TYPE  MOUNTPOINT
sda                8:0    0    1G  0 disk  
└─sda1             8:1    0 1023M  0 part  
  └─boot         252:3    0 1021M  0 crypt /boot
sdb                8:16   0   10G  0 disk  
├─sdb2             8:18   0    1K  0 part  
└─sdb5             8:21   0  9.5G  0 part  
  └─lvm          252:0    0  9.5G  0 crypt 
    ├─MDISK-swap 252:1    0  500M  0 lvm   [SWAP]
    └─MDISK-root 252:2    0    9G  0 lvm   /
sr0               11:0    1 1024M  0 rom   

parted

root@ubuntusrv2tmp:~# parted /dev/sda print
Model: ATA VBOX HARDDISK (scsi)
Disk /dev/sda: 1074MB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  1074MB  1073MB  primary               boot

root@ubuntusrv2tmp:~# parted /dev/sdb print
Model: ATA VBOX HARDDISK (scsi)
Disk /dev/sdb: 10.7GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start  End     Size    Type      File system  Flags
 2      525MB  10.7GB  10.2GB  extended
 5      526MB  10.7GB  10.2GB  logical

/etc/default/grub

GRUB_DEFAULT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=2
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT=""
GRUB_CMDLINE_LINUX=""
GRUB_ENABLE_CRYPTODISK=y

/etc/grub.d/40_custom

menuentry "Other Linux" {
insmod part_msdos
insmod lvm
insmod ext2
insmod luks
insmod cryptodisk
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
                  search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 1149241b-eac6-45b6-b926-c1d9ceddd4ae
                else
                  search --no-floppy --fs-uuid --set=root 1149241b-eac6-45b6-b926-c1d9ceddd4ae
                fi
                echo    'Loading Other Linux TMask ...'
        linux /vmlinuz-4.4.0-87-generic root=/dev/mapper/MDISK-root ro
        initrd /initrd.img-4.4.0-87-generic
}

blkid

/dev/mapper/lvm: UUID="0HIkKp-s40v-KK61-yn79-Vwwg-sOIO-s4Jgys" 
TYPE="LVM2_member" 

/dev/mapper/MDISK-root:
UUID="bfe2f433-3249-4309-a13c-a8b1baffa64b" TYPE="ext4" 

/dev/sda1:
UUID="11486177-e7ca-4285-a34b-60c557759993" TYPE="crypto_LUKS"
PARTUUID="d08c0112-01" 

/dev/sdb5:
UUID="30a2dd4e-9b46-42df-a363-8127372de1f7" TYPE="crypto_LUKS"

/dev/mapper/MDISK-swap: UUID="188b491f-5fdc-4d83-8f08-046becab333e"
TYPE="swap" 

/dev/mapper/boot:
UUID="1149241b-eac6-45b6-b926-c1d9ceddd4ae" TYPE="ext4"

/etc/fstab

UUID=1149241b-eac6-45b6-b926-c1d9ceddd4ae /boot           ext4    defaults        0       1
UUID=188b491f-5fdc-4d83-8f08-046becab333e              none          swap      defaults              0      0
UUID=bfe2f433-3249-4309-a13c-a8b1baffa64b /               ext4    errors=remount-ro 0       2