More importantly, end-to-end encryption means that your desktop&#x2F;laptop&#x2F;tablet&#x2F;phone&#x2F;TI-83 is doing the crypto, especially signatures.<p>On a somewhat related note, I remember reading some documentation on a one-time password scheme, which I can&#x27;t find anymore.  It briefly mentioned something about using DES calculators to handle crypto signatures (for what reason i cannot remember).  For our purposes, a PGP&#x2F;GPG hand-held device would be neat, though perhaps cumbersome to actually user.