[Cryptography] Hash Password, Nonce

(1) Hashed Password

  stored hashed password H(p)in the Database, instead of plaintext password  use random number,called SALT (salt), together with P to add in the hash function.

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(2) Nonce

Problems:

    1. Man in the middle(Modify)    2. Reply(retransmit)

Countermeasures:

  1. Nonce to prevent Replay      random number, just used once      ensure the messages are fresh  2. Timestamp to prevent Man in the middle      require synchronized clocks      means limited time to do something