Wallet private key is the main secret of the card. It will be generated by the card on the factory or by the user using the Create wallet method. It is never revealed and accessible by the host application via the NFC interface. COS will internally use a wallet private key only during execution of Sign and some attestation commands.
Blockchain reference A public key is used to compute a unique address in the blockchain. A private key is used to sign transactions originating from this address. So only the owner of the private key can initiate the transfer of funds from this address. In other words, whoever owns the private key owns the crypto funds. In our case, who owns the card — owns the crypto funds.
Tangem Card is equipped with a True Random Number Generator that's used for generating private keys. This approach makes it impossible to generate the same key, as well as the ability to predict the result of the operation.
Cards can carry up to 40 wallets.
Supported elliptic curves and signing algorithms: