I've done it using a $100 Cryptostick (Now Nitrokey). Here's a guide from Mozilla: https://blog.mozilla.org/security/2013/02/13/using-cryptostick-as-an-hsm/ htt

I've done it using a $100 Cryptostick (Now Nitrokey). Here's a guide from Mozilla: https://blog.mozilla.org/security/2013/02/13/using-cryptostick-as-an-hsm/ https://blog.mozilla.org/security/2013/02/13/using-cryptosti... https://www.nitrokey.com/ https://www.nitrokey.com/