A method of and an authentication server for distributing a key are disclosed. According to an embodiment of the present invention, the method of distributing a key, which is distributed by an authentication server connected with wireless terminals through a communication network, for encrypting and decrypting data in accordance with providing a service can include: obtaining characteristic information by decrypting encrypted characteristic information that has been received from each of n number of wireless terminals; generating a random key; generating a group key used for encrypting and decrypting data in accordance with providing a service; and generating a distribution key by using the random key, the group key and the characteristic information, and transmitting the distribution key to each wireless terminal.