Secure Multi Signature Bitcoin Wallet

One key AES encrypted on our server another stored on your smartphone.

Android Compatible Wallets

To register/login scan the QR code with a compatible android/iphone app.

iOS Compatible Wallets

We secure your coins using 2 private keys you control.

Splitting keys in this way adds a whole new level of security for your Bitcoins.

Multi Signature

We split our keys between your smartphone and encrypted on our server.

Out of band

Payments require your secure passphrase AND a signature from your phone.

Keys in your control

The key held on our server is encrypted with your passphrase in the browser.

Cryptographically Secure


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Wallet comparison chart

How does CarbonWallet compare to other Bitcoin wallets?

Feature CarbonWallet Coinbase/Circle Blockchain.info
Multi Signature Transaction Support
Allows keys to spread across devices for maximum security
Yes No No
BIT ID Authentification
Use smartphone to access your wallet making the it immune to keyloggers and other malware.
Yes No No
HD Wallet
Easy wallet backups just by writing down a passphrase.
Yes No No
Operator has access to funds ?
If the wallet operator is hacked will you lose your coins ?
No Access Full Access Partial
Out of Band 2 Factor
Out of band 2 factor authentication means your 2 factor security is not open to social engineering.
Yes No No

Technical details

A more detailed breakdown for the more technically inclined.

How are the private keys managed ?

We operate a 2 of 2 multi signature wallet. When you pair your smartphone with CarbonWallet you send us an extended public key. We never see the private key on your phone.

The second private key is generated in the browser (similar to blockchain.info/wallet) and encrypted in the browser with your passphrase.

We then combine the 2 extended public keys to create the 2 of 2 wallet.

How are out going payments signed ?

Carbon wallet can create a Bitcoin transaction with the 2 extended public keys but can't sign it.

The first signature is generated with javascript in the browser when you enter your passphrase to decrypt the AES encrypted private key.

The second signature is supplied by your smartphone. You have to scan a QR code which gives the pone the information required to retrieve the transaction form our servers. The smartphone signs the transaction and sends it back to CarbonWallet.

When we receive the fully signed transaction we broadcast it to the Bitcoin network.

How do I backup my private keys ?

Your smartphone wallet application should have its own backup procedure. For example the onchain.io android wallet allows you to a BIP38 backup passphrase.

The private key held encrypted on our servers can de downloaded as a Paper wallet and stored safely.


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