The security of a cryptosystem in most cases relies on the key being kept secret. Quantum key distribution (QKD) enables two authenticated parties without other prior information to share a perfectly secure key. However, repeatedly using the same key to encrypt many different messages is not perfectly secure. A trivial method to obtain a secret key is to use QKD to reestablish a new key for each message. In this thesis, we study an efficient method to update the keys. We call this method quantum key evolution (QKE). The QKE provides a new secret key in each round of the protocol. Therefore, a new secret key is established for next round of protocol execution. We study two problems to present secure schemes applying the QKE. First, we present a new quantum message transmission protocol, to transmit long secret message using less quantum bits than the methods of incorporating QKD with one-time pad, as well as some quantum secure direct communication protocols. Second, we present three-party authenticated quantum key distribution protocols which enable two communicating parties to authenticate the other's identity and establish a session key between them via a trusted center. For the security of our protocols, we give formal standard reduction proofs to the security of our protocols. We show that the security of our protocol is equivalent to the security of BB84 protocol which has been proved to be unconditionally secure. Therefore, our protocols are unconditionally secure.