What is "nitrokey"

Nitrokey is an open source USB key to enable secure encryption and signing of data. The secret keys are always stored inside the Nitrokey which protects against malware (such as computer viruses) and attackers. A user-chosen PIN and a tamper-proof smart card protect the Nitrokey in case of loss and theft.The hardware and software of Nitrokey are available as open source, free software and open hardware which enables independent parties to verify the security of the device. Nitrokey is supported on Microsoft Windows, Linux, and Mac OS X.