Avoid duplicate nonces.
Avoid duplicate nonces.

The seed to srandom () must change with every request, otherwise
we will get the same nonce and the validation server will reject
the request.

At the moment we don't consider it necessary to have a
cryptographically secure nonce generation but rather favour
portability and simplicity.

Yubico/yubico-c-client,Yubico/yubico-c-client,kellyjf/yubi,Yubico/yubico-c-client,kellyjf/yubi