Software Cold Wallet — RHODL Crypto Deposit Box

  • owns a crypto, preferably a mainstream one (bitcoin, ethereum, litecoin)
  • uses digital wallets to buys/sell/trade crypto
  • is 30–40 years of age
  • is active participant of the crypto community (reddit crypto groups, crypto twitter)
  • uses an android mobile device
  • is interested in new applications for crypto market
  • knows what is a cold wallet
  • preferably runs a full node of any major cryptocurrency
  • has relatives/close ones that she wants to provide for with her digital assets
  • being able to store private key of the digital asset in a digital deposit box — it must be safe and comply with the well known crypto adage — “not your keys not your coins”
  • being able to share the private key but in a such way that full control (security) over the coins is preserved and amount is not disclosed
  • being able to attach a personal note to the beneficiary who eventually unlocks the box — so one can place instruction how to use the private key to access the assets or just say a last farewell word.
  • being able to timelock the box so the beneficiary can’t access the asset in an uncontrolled way
  • being sure that in case of an unexpected situation (illness, accident) the coins will not be lost forever (due to the fact, that nobody else holds private key) — conversely the private key will be revealed to the relatives/beneficiary on such event

Shared But Secure & Timelocked — How It Works

  • Hodler aka owner of the digital asset. This is a person that has full control over digital coins (holds the private key). The hodler wants to make a crypto notary deposit box to secure his relatives in case he can’t access the coins (severe illness, accident).
  • Beneficiary/relative/close one. This is a person that will eventually gain full access to the digital asset. Until then the person simply knows that there is such an asset but has no control over it nor has any insight into value of the asset.
  • RHODL application. This is a Peer2Peer coordinator, that bounds the hodler and the beneficiary. The application does not have nor store the private key. The application only orchestrates the creation and unlocking process of the crypto notary deposit box. It also enforces timelock constraint on the deposit box.

Security Considerations

  • Private key that controls coins is not shared. It does not leave the mobile device.
  • Private key that controls coins is encrypted into compound secret (the actual crypto deposit box processed by the application) using the Shamir Secret Sharing algorithm which is proved to be cryptographically secure
  • Only encrypted private key locked in the crypto deposit box is shared between the Holder’s device and RHodl application cloud. Even on a rare occasion of a security breach in RHodl app the attacker will not reveal private keys of Hodlers due to the fact that the app only stores Shamir encrypted versions of the keys.
  • There are two parts of the unlock key generated. The first key (the “A” Key) is presented to the Hodler. The second key ( the “B” key) is presented to the beneficiary. The beneficiary can’t unlock deposit box as the beneficiary holds only one of two required unlock keys.
  • The Hodler can put his “A” key in his last will or in a bank deposit box or in any way convenient to him. He can rest assured that neither the bank nor notary will not gain control over his coins as having only one key is insufficient to unlock crypto deposit box.
  • In a rare occasion when the beneficiary somehow gets unauthorized access to the Hodler’s “A” Key there is a timelock prevention mechanism implemented. As the encrypted deposit box is managed by the RHodl cloud application the deposit box will not be available for unlock until the timelock is elapsed. So one can even image a situation when the Hodler shares his key with the Beneficiary the very moment the crypto deposit box is created. The Hodler can rest assured that timelock prevents from opening the deposit box too early.
  • Having the mobile phone with the application stolen or hacked is not a problem. The private key is safe in the Shamir encrypted way in the cloud. So the mobile phone attacker will not benefit from having full control over the mobile device.

Sort of a Cold Wallet?

Download the app

More reading

  • How to — Creating Crypto Deposit Box. More detailed description of the coins encryption experience accompanied by UI diagrams and mockups.
  • How to — Unlocking Crypto Deposit Box. More detailed description of the coins unlocking experience accompanied by UI diagrams and mockups.
  • Hands on coding experience recorded live on video sessions.




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Yenten Observer

Yenten Observer

Cryptocurrency freak. Freedom, ecology and free market above all.

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