A method for increasing the security of private keys is provided that includes generating transaction data at a device operated by a user and processing the transaction data. Moreover, the method includes determining whether the user permits using a private key that is associated with the user and with a public-private key pair of the user. The private key is stored in a computer system different from the device. Furthermore, the method includes authenticating the user when the user permits using the private key, applying the private key to other data after successfully authenticating the user, and transmitting the other data to the device. The method also includes conducting a transaction with the transaction data.