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4 mins read

Cryptnox: Building state-of-the-art smart card private key safety

Project: Developing user-friendly, secure smart cards

Cryptnox is a Swiss company focused on developing smart card hardware wallets with advanced features for delivering the best user-friendly experience and solving the problems of private key management, authentication, and transaction traceability.

HTEC helped Cryptnox develop a unique user-friendly iOS companion application—together with a full-fledge CLI (command line interface) for total control over the cards—that allows users to have a backup solution and to complete transactions on blockchain networks with the highest level of security.

Challenge: The need for backup smart cards for private key safety

Hardware wallets are a key component of a 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 mnemonic phrase.

It is impossible to forge a signature without a private key, so no one else can make a transaction on a user’s behalf without it. Private keys stored on the hardware wallet are protected by a PIN or passphrase. Should a thief steal a user’s hardware wallet, it is 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 cannot be stolen. 

HTEC client, Cryptnox, wanted to make this entire process even safer by allowing customers to use a hardware wallet without having to work with the mnemonic phrase. Cryptnox came up with an idea to offer users two separate smart cards that can generate the same private key inside of them without exposing it to the outside world.

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

Solution: An iOS app that manages two smart cards

HTEC 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 Cryptnox’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, the HTEC team had to make sure that the encryption algorithms used by some blockchains are not standardized by the standards body, as 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

Success: A simple backup solution that always protects your assets

The biggest obstacle with handling cryptocurrencies is the enormous responsibility trusted upon users to make sure their assets are always secure.

Ultimately, this software would provide users with a 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 gives them peace of mind that their assets are always secure without having to worry about potential theft.


Our collaboration with HTEC was very productive. Together, we achieved 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

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