Overwriting disks and use it as containers

[Mirtk-Srdja-Plandr]

Hello everyone, I have a question about tird. Quoting from the project's main page :

With tird, you can:
[...]
2.Overwrite the contents of block devices and regular files with random data. This can be used to prepare containers and to destroy residual data.
[...]
4.Create steganographic (hidden, undetectable) user-driven file systems inside container files and block devices. Unlike VeraCrypt and Shufflecake containers, tird containers do not contain headers at all; the user specifies the location of the data in the container and is responsible for ensuring that this location is separated from the container.

It doesn't work at all. I done my tests using the standalone executable for Linux (using a Debian-based distribution), and pasting for example /media/user/disk-name when selecting file to overwrite with random or to use as container, it output E: [Errno 21] Is a directory: '/media/user/disk-name/'. How can I solve the problem ?

[hakavlad]

Hi!

E: [Errno 21] Is a directory: '/media/user/disk-name/'.

How can I solve the problem ?

Overwrite a file, not a directoty! It overwrites file contents. Contents of one file.

[hakavlad]

$ tird

                       MENU
    ———————————————————————————————————————————
    0. Exit              1. Info & Warnings
    2. Encrypt           3. Decrypt
    4. Embed             5. Extract
    6. Encrypt & Embed   7. Extract & Decrypt
    8. Create w/ Random  9. Overwrite w/ Random
    ———————————————————————————————————————————
A0. Select an option [0-9]: 8
    I: action #8:
        create file of specified size with random data
D3. Output file: 1m
    I: new empty file '1m' created
D4. Output file size in bytes: 1000000
    I: size: 1,000,000 B (976.6 KiB)
    I: writing random data
    I: written 100.0%; 976.6 KiB in 0.0s; avg 109.9 MiB/s
    I: writing completed; total of 1,000,000 B written
    I: action completed

                       MENU
    ———————————————————————————————————————————
    0. Exit              1. Info & Warnings
    2. Encrypt           3. Decrypt
    4. Embed             5. Extract
    6. Encrypt & Embed   7. Extract & Decrypt
    8. Create w/ Random  9. Overwrite w/ Random
    ———————————————————————————————————————————
A0. Select an option [0-9]: 9
    I: action #9:
        overwrite file contents with random data
D3. File to overwrite: 1m
    I: path: '1m'; size: 1,000,000 B (976.6 KiB)
D5. Start position [0; 1000000], default=0: 
    I: start position: 0 (offset: 0 B)
D6. End position [0; 1000000], default=1000000: 
    I: end position: 1000000 (offset: 1,000,000 B)
    I: data size to write: 1,000,000 B (976.6 KiB)
    W: output file will be partially overwritten!
P0. Proceed overwriting? (Y/N): 1
    I: writing random data
    I: written 100.0%; 976.6 KiB in 0.0s; avg 104.7 MiB/s
    I: writing completed; total of 1,000,000 B written
    I: syncing output data to disk
    I: synced in 0.0s
    I: action completed

[hakavlad]

/media/user/disk-name/ is mountpoint, not a disk name.

To overwrite disk, filename should be something like /dev/sdX.

See

$ lsblk
NAME                                          MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda                                             8:0    0 465,8G  0 disk  
├─sda1                                          8:1    0    30M  0 part  
├─sda2                                          8:2    0   9,4G  0 part  /boot
└─sda3                                          8:3    0 456,3G  0 part  
  └─sda3_crypt                                254:0    0 456,3G  0 crypt /
sdb                                             8:16   0 931,5G  0 disk  
├─sdb1                                          8:17   0    37M  0 part  
├─sdb2                                          8:18   0  37,3G  0 part  
├─sdb3                                          8:19   0  10,2G  0 part 

Use lsblk or sudo fdisk -l to check disk names.

[hakavlad]

Use with sudo to overwrite device contents. Example:

$ sudo tird

                       MENU
    ———————————————————————————————————————————
    0. Exit              1. Info & Warnings
    2. Encrypt           3. Decrypt
    4. Embed             5. Extract
    6. Encrypt & Embed   7. Extract & Decrypt
    8. Create w/ Random  9. Overwrite w/ Random
    ———————————————————————————————————————————
A0. Select an option [0-9]: 6
    I: action #6:
        encrypt file contents and comments;
        write cryptoblob over container
C0. Use custom settings? (Y/N, default=N): 
    I: use custom settings: False
D1. File to encrypt and embed: 1m
    I: path: '1m'; size: 1,000,000 B (976.6 KiB)
D2. Comments (optional, up to 512 B): 1m random file
    I: comments will be shown as ['1m random file']
D3. File to overwrite (container): /dev/sdc
    I: path: '/dev/sdc'
    I: size: 16,357,785,600 B (15.2 GiB)
D5. Start position [0; 16356584603]: 9000000000
    I: start position: 9000000000 (offset: 9,000,000,000 B)
K1. Keyfile path (optional): 
K2. Passphrase (optional): 
K2. Confirm passphrase: 
    I: passphrase accepted
K2. Passphrase (optional): 
    W: output file will be overwritten from 9000000000 to maximum 9001200997!
P0. Proceed overwriting? (Y/N): 1
    I: deriving keys (time-consuming)
    I: keys derived in 3.9s
    I: data size to write: 1,050,980 B (1.0 MiB)
    I: reading plaintext, writing cryptoblob
    I: written 100.0%; 1.0 MiB in 0.0s; avg 31.9 MiB/s
    I: writing completed; total of 1,050,980 B written
    I: syncing output data to disk
    I: synced in 0.1s
    W: cryptoblob location is important for its further extraction!
    I: remember cryptoblob location in container:
        [9000000000:9001050980]
    I: pockets (padding) location in output file:
        [9000000016:9000026596] — 26,580 B (26.0 KiB)
        [9001027140:9001050964] — 23,824 B (23.3 KiB)
    I: action completed

[hakavlad]

I hope to write a tutorial on this soon.

[hakavlad]

W: output file will be overwritten from 6000000000 to maximum 6000471062!

This means max POSSIBLE end position.

[Mirtk-Srdja-Plandr]

Ok thanks for the trick with the start and end position. But still, I know how to format exFAT, I saw the option, but I cn't select it, and it is marked in grey. I don't know why, gnome-disks refuse to format my USB drive in exFAT. But thanks for the tips.

[Mirtk-Srdja-Plandr]

I just tested it again and the feature works just well. Congratulations you just got one more user (joke apart thanks for the patience, there are many brilliant developers / maintainers that simply refuse to help neophytes while this should be a part of their work).

[hakavlad]

it is marked in grey

sudo apt install exfatprogs

[hakavlad]

Thank you! Feel free to ask more questions!