Thread by @CoinCornerDanny

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Introducing “Hoffline”

The 1st automated #Bitcoin hot wallet where the private keys never go online, fully air-gapped.

Take a look at the video and I’ll explain below 👇

2/

High level device overview

1x Offline (Blue)
- Raspberry pi
- Screen
- Camera
- Bitcoin wallet - private keys

1x Online (Orange)
- Raspberry pi
- Screen
- Camera
- Ethernet cable
- Bitcoin wallet - watch only

Cheap cost for setup

3/

High level how it works

Online Device:
- Gets transactions to send from database
- Creates unsigned transaction
- Displays QR code with unsigned transaction data

Offline device
- camera automatically scans QR code

4/

Offline Device
- Validates request and signs transaction
- Displays QR code containing signed transaction data

Online Device
- Camera automatically scans QR code
- Broadcasts signed transaction

*Some detail redacted for ease of explanation

5/

The idea?

Myself and @coincornerzakk one morning were frustrated at large exchanges adding shitcoins rather than innovating

This led us into talking ridiculous ideas - “why not create a hot wallet that’s purely offline”

Within 15 minutes we’d scoped out the first concept

6/

We spent a few months thinking through the concept and ironing out issues we spotted along the way before development began

Credit also to Jack, @CoinCornerDave and @alex_delaney for helping build/shape Hoffline

7/

For exchanges?

Exchanges run hot wallets where the private key is stored online in some manner. There are solutions such as BitGo that use multisig to help alleviate the problem, but still the private key is not stored purely offline.

8/

Is this a gimmick?

We’re still early days with this R&D project, but this is another step forward, we'll gather feedback and see where this could go.

We have other mitigations in place throughout to help protect from various attack vectors - I haven’t covered full detail

9/

Speed an issue?

Not for the current purpose - most exchanges batch transactions periodically every 10 minutes on avg. It can still create and broadcast the transaction in seconds and we are already aware of some changes we could make to speed the process up.

10/

We are already looking at improvements for speed and simplicity - as crazy as using @Blockstream satellite to receive the blocks and run a full node on the Offline device - which allows for less data to be embedded in the QR codes and allows us to run a Bitcoin Core node.

11/

Multisig?

Yes you can also do an automated multisig setup, this will help mitigate the physical attack vector as you could have the 2 (or more) setups in different physical locations around the world.

12/

Another consideration - Not just exchanges - @getumbrel

Umbrel nodes and the likes are becoming popular - we’re exploring how Hoffline can be used in tandem with your Umbrel node to allow additional security, allowing your private keys to be kept securely offline.

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I’m proud of what the team has achieved over the 7 years at CoinCorner.

We took a small angel investment of £150,000 back in 2015 and nothing since, integrated Lightning for customers and merchants, launched the 1st #Bitcoin cashback in the UK ....

14/

.... contributed to Bitcoin core, worked with regulators, helped contribute to the education of Bitcoin and more.

15/

It can be frustrating to watch companies with hundreds of millions in funding not innovating and driving #Bitcoin forwards the way we’d all like to see.

But I guess that’s where the smaller guys like ourselves come in, ....

16/

.... continuing to drive #Bitcoin forward for the future of money. @jackmallers is a great example of the small guy making huge strides recently and we want to be part of this.

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We believe in looking at the longer term view and will continue to innovate and stay at the forefront. The team we have at @CoinCorner is incredible and will continue to help build the future global monetary system for years to come.