---
tags: withdrawals, key_rotation
---

# How to use dc4bc

Part of [withdrawal credentials rotation plan](/@lido/SJ1fiW58i)

At this stage of the ceremony, all participants have installed the necessary software, and have already set up communication [exchanged public communication keys] of workstations.
* Cold machine
* dc4bc_airgapped
* qr-tool
* Hot machine
* qr-tool
* dc4bc_cli
* dc4bc_d

1. Participants must agree offline who will launch the **sign_baked** first.

    ./dc4bc_cli sign_baked <hash_of_operation> <start_number> <end_number> 


for examle

    ./dc4bc_cli sign_baked c04f3d54718dfc801d1cbe 0 10
    ./dc4bc_cli sign_baked c04f3d54718dfc801d1cbe 10 20
    ...
    ./dc4bc_cli sign_baked c04f3d54718dfc801d1cbe 18500 18632

2. **All participants call a command**

   $ ./dc4bc_cli get_operations --listen_addr localhost:8080
    
    Please, select operation:
    -----------------------------------------------------
     1)             DKG round ID: c0401d1cbe86e3a3152c36763af3b8f2
                    Operation ID: 83e14a21c0116094630654d923ba9600
                    Description: Bls rotation sign ceremony round
    -----------------------------------------------------
    Select operation and press Enter. Ctrl+C for cancel

*When you promt 1. Commad saves data into .json.*

3. Open qr-tool prepated on step 1 and encode data.
4. A generated gif file you have show to your webcam on arigraped machine in qr-tool, simular like on pictures below:

|  |  |
| -------- | -------- |
|  |  |

5. After you have decoded gif into json file on arigraped machine eval the `read_operation` command in airgapped prompt:

    Waiting for command...
    >>> read_operation
    > Enter the path to Operation JSON file:

> A command'll ask a path for the decoded file. And result will be new one file.

6. That file user has to encode into gif though qr-encode tool simular line in step "3."
7. File that we got in 6 section - user has to decode on machine where dc4bc cli works.
8.

    $ ./dc4bc_cli --listen_addr localhost:8080 read_operation_result <path_to_operation_result_from_step_8.json>

9. After these actions, when a quorum of signatures (6/11) will be collected, the signature of the signed message for key rotation will publish into the kafka topic