nonce

This means that it is safe to use a randomly generated nonce, while randomly generating a 64-bit nonce would result in collisions eventually.

The PTK is a hash function computed from the PMK, Alice's random nonce, Bob's random nonce, Alice's MAC address, and Bob's MAC address.

The core feature about XSalsa20 is that it supports a 192-bit nonce instead of the 64-bit nonce of ChaCha20.

The convention is to use half the block for the nonce and half for the counter, which, in an 8-byte block, means you're working with a 32 bit nonce (much too small) and a 32 bit counter.

Another possibility is they were merely comparing the submitted nonce to the nonce on file.

The nonce is the expected thing to tweak, but given current difficulty, it's pretty likely that trying all the nonces will fail.

To fix the replay attack, you also need to sign a nonce from the peer (or its ephemeral public key) to prove that the message is fresh.

If a nonce had never been generated for a user, the database may have contained an empty string.

That said, it would seem that the first nonce being random and then incremented would likely work well.

Do you send a nonce back to the user and check it before completing the banning process?

Obviously, it is much faster than the scheme proposed here and removes the biggest implementation flaw in nonce-based stream ciphers.

If you don't want to be anonymous anymore, you can sign nonce with your official and with your temporary key.

But miners usually change the "coinbase" transaction (which is the transaction that grants bitcoins to the miners) by putting an extra nonce in there, since there's extra room and the transaction can be modified without messing anything up.

Our strategy (designed for a "remember me" checkbox) is actually a little more cautious than a simple nonce, in that we actually generate two tokens: One is a selector (used to retrieve a record from the database, which is an operation that cannot be performed in constant time), while the other is a validator.