Re: Slow unlock of the LUKS device at boot

Also, do you suggest changing the order of keys in the keyslot for the 
partition with LVM volume?

On 2022-11-29 20:50, Lamy Geier wrote:
> My boot partition (/dev/nvme0n1p1) is using LUKS1. And another partition 
> (/dev/nvme0n1p5) is using LUKS2 which has LVM with root volume,  home 
> volume and swap volumes. Both of these have same passphrase.
> 
> I am using Grub. While booting I enter the passphrase to unlock the boot 
> partition. To automatically unlock the partition with LVM volumes, I 
> have created a keyfile (boot_os.keyfile) which is stored in the device 
> itself, which is used to unlock it. I have created it as follows:
> 
> ```bash
> # echo "KEYFILE_PATTERN=/etc/luks/*.keyfile" >> 
> /etc/cryptsetup-initramfs/conf-hook
> # echo "UMASK=0077" >> /etc/initramfs-tools/initramfs.conf
> ```
> 
> - Create a randomised key-file of 4096 bits (512 bytes), secure it, and 
> add it to the LUKS volumes (Man-pages for dd chmod):
> 
> ```bash
> # mkdir /etc/luks
> # dd if=/dev/urandom of=/etc/luks/boot_os.keyfile bs=512 count=1
> 1+0 records in u=rx,go-rwx /etc/luks
> 1+0 records out
> 512 bytes (0.5 kB, 0.5 KiB) copied, 0.0002368 s, 17.3 MB/s
> 
> # chmod u=rx,go-rwx /etc/luks
> # chmod u=r,go-rwx /etc/luks/boot_os.keyfile
> 
> # cryptsetup luksAddKey /dev/nvme0n1p1 /etc/luks/boot_os.keyfile
> Enter any existing passphrase:
> 
> # cryptsetup luksAddKey /dev/nvme0n1p5 /etc/luks/boot_os.keyfile
> Enter any existing passphrase:
> ```
> 
> Add the keys to the crypttab:
> 
> ```bash
> # echo "LUKS_BOOT UUID=$(blkid -s UUID -o value ${DEVP}1) 
> /etc/luks/boot_os.keyfile luks,discard" >> /etc/crypttab
> # echo "${DM}5_crypt UUID=$(blkid -s UUID -o value ${DEVP}5) 
> /etc/luks/boot_os.keyfile luks,discard" >> /etc/crypttab
> ```
> 
> The above is taken from: [Full_Disk_Encryption_Howto_2019 - Community 
> Help 
> Wiki](https://help.ubuntu.com/community/Full_Disk_Encryption_Howto_2019#Post-Installation_Steps)
> 
> ---
> 
> # Issue
> 
> The boot partition unlocks very quickly (5 seconds) but the LVM volume 
> takes about 6 minutes to unlock.
> 
> Following are the key dump of both these partitions. With the keyslot 0 
> in both being the same passphrase, and keyslot 1 being the key file:
> 
> ```
> $ sudo cryptsetup luksDump /dev/nvme0n1p1
> Place your right index finger on the fingerprint reader
> LUKS header information for /dev/nvme0n1p1
> 
> Version:        1
> Cipher name:    aes
> Cipher mode:    xts-plain64
> Hash spec:      sha256
> Payload offset: 4096
> MK bits:        512
> MK digest:      ec 22 27 de c1 ef 40 0f a5 cf 37 d3 96 5c d5 b2 6e c8 dd 90
> MK salt:        62 1a 05 81 ba 60 3b 0d b1 8a 9f f0 04 98 27 54
>                  06 b6 8d 72 53 23 09 47 ea 5f 80 1d d7 c5 ca 50
> MK iterations:  305173
> UUID:           586de9a0-14c7-40d7-b721-7fdba2e3b184
> 
> Key Slot 0: ENABLED
>          Iterations:             1000
>          Salt:                   4b f1 99 85 84 a5 00 d6 a4 e8 e1 07 35 
> b4 da a1
>                                  fc 97 59 5f 4c f8 e1 9b 49 71 29 af e5 
> 56 b1 19
>          Key material offset:    8
>          AF stripes:             4000
> Key Slot 1: ENABLED
>          Iterations:             4848906
>          Salt:                   91 70 85 49 f3 31 e8 53 1f 39 aa 6d 7a 
> 3e 84 de
>                                  e4 3f bd 3d 65 bf f6 b1 e6 8c 15 fa 34 
> b9 e3 e0
>          Key material offset:    512
>          AF stripes:             4000
> ```
> 
> ```
> $ sudo cryptsetup luksDump /dev/nvme0n1p5
> LUKS header information
> Version:        2
> Epoch:          10
> Metadata area:  16384 [bytes]
> Keyslots area:  16744448 [bytes]
> UUID:           ee8854e8-54f6-4f7b-b326-02fdee357d0e
> Label:          (no label)
> Subsystem:      (no subsystem)
> Flags:          (no flags)
> 
> Data segments:
>    0: crypt
>          offset: 16777216 [bytes]
>          length: (whole device)
>          cipher: aes-xts-plain64
>          sector: 512 [bytes]
> 
> Keyslots:
>    0: luks2
>          Key:        512 bits
>          Priority:   normal
>          Cipher:     aes-xts-plain64
>          Cipher key: 512 bits
>          PBKDF:      argon2id
>          Time cost:  1000
>          Memory:     1048576
>          Threads:    4
>          Salt:       93 17 44 b3 39 82 ab 0c 20 81 0b 2b 8d 38 b1 42
>                      57 53 bf ad 11 5c d5 f5 8e 42 47 45 21 73 74 84
>          AF stripes: 4000
>          AF hash:    sha256
>          Area offset:806912 [bytes]
>          Area length:258048 [bytes]
>          Digest ID:  0
>    1: luks2
>          Key:        512 bits
>          Priority:   normal
>          Cipher:     aes-xts-plain64
>          Cipher key: 512 bits
>          PBKDF:      argon2id
>          Time cost:  9
>          Memory:     1048576
>          Threads:    4
>          Salt:       b9 84 4c ee e5 38 5d 3e 7e c3 1f 12 b3 6c 42 9b
>                      a4 61 7c f8 12 55 99 25 fe d6 76 15 4b 65 11 66
>          AF stripes: 4000
>          AF hash:    sha256
>          Area offset:32768 [bytes]
>          Area length:258048 [bytes]
>          Digest ID:  0
> Tokens:
> Digests:
>    0: pbkdf2
>          Hash:       sha256
>          Iterations: 305529
>          Salt:       db 22 26 2b b0 dc 12 19 a1 e1 13 d2 98 92 43 2c
>                      d3 e6 f2 da 9a 08 e5 a3 56 42 f5 e7 b0 89 bc 75
>          Digest:     bb e0 6e 95 50 0c 86 ce 3a 1b bd 7e 7b da 16 ba
>                      84 c7 9a 41 a2 09 9c b1 a5 a6 3d 80 31 5a 27 64
> ```
> 
> # Help request?
> 
> Can you please suggest if I need to change the order of the keys or 
> change the iteration time cost or any other parameter to make my LVM 
> volume to unlock faster?
> 
> Note: My passphrase has high entropy and the keyfile also has high 
> entropy as it is generated with random numbers.
> 
> 

-- 
Thanks and Regards

Lamy