3 mins read

Cryptnox: Building State-of-the-Art Private Key Safety



About the project

Cryptnox is focused on developing smart cards with advanced functionalities to enable the best user-friendly experience along with solving the problems of private key management, authentication, and transactions traceability.

HTEC Group helped them develop a unique user-friendly iOS companion application, together with a full-fledge CLI for total control over the cards, that allows users to have a backup solution and, therefore, do transactions on Blockchain networks with the highest level of security.


Hardware wallets are a key component of the blockchain ecosystem that provides security and utility when interacting with blockchains. The hardware wallet stores your private key and signs transactions which open the lock to your address on the blockchain where your assets live. Hardware wallets are usually backed up with a recovery, a mnemonic phrase.

It’s impossible to forge the signature without the private key, so no one else can make a transaction on users’ behalf without it. Private keys stored on the hardware wallet are protected by a PIN or passphrase. Should a thief take possession of the user’s hardware wallet, it’s nearly impossible for them to extract the user’s keys. As the signing procedure is done on the hardware wallet, the private key is never exposed to the network so it can’t be stolen. 

Our Client Cryptnox wanted to make this entire process even safer by allowing the user to use a hardware wallet without having to work with the mnemonic phrase. They came up with an idea to offer users two separate cards, hardware wallets, which can generate the same private key inside of them without ever exposing it to the outside world.

This would allow users to use one card when they are making transactions and if that card gets stolen, or lost, they will have the backup, the other card which they have previously placed in a safe or some other secure place. As the cards are identical, the user can transfer the assets to another account from the backup card. Cryptnox needed somebody to help them implement their ideas in an innovative way — they approached HTEC Group to help them develop applications with a user-friendly interface that could perform a variety of advanced functionalities and turn their idea into a reality.


We developed a complete iOS companion application that allows users to do transactions on Blockchain networks. The solution supports Bitcoin and Ethereum, and the user can, in CLI, use more granular commands, including working with smart contracts and the EOS network. At its core, it is a modern crypto wallet that uses our client’s cards for transaction signing. We wanted to develop something new — the most efficient solution that would allow users to manage these two cards. 

Our ultimate goal was to ensure a high level of private key safety.

While developing this solution, we had to pay attention that the encryption algorithms used by some blockchains are not standardized by the standards body, and this makes them less available in the iOS ecosystem.

Web3 is being adopted at extreme speeds. Although private keys are designed to handle the most sensitive and crucial information easily and with high-level security, they are still cumbersome and error prone. We are excited to be able to work with Cryptnox in providing users with a more seamless solution that can drive interest among even more users and encourage them to join this new exhilarating world.

– Mladen Milanković

Delivery Lead at HTEC Group


The biggest obstacle with handling cryptocurrencies is the enormous responsibility trusted upon the user to make sure their assets are always secure. Ultimately, this software would provide users with the backup solution that would eliminate the handling of the mnemonic phrase and therefore keep their assets safe in an easier way. In other words, it provides them with a piece of mind that their assets are always secure, without having to worry about potential misfortunate scenarios. 

Our collaboration with HTEC Group was very productive, we achieved together very interesting technological breakthroughs. Our progress is bringing the user experience of our card solutions closer to the ones of existing bank cards, but with direct communication to chains. This potentially opens up a wide range of new applications.

– Sebastien Armleder

CEO, Cryptnox SA

Let’s take the first step together.