Abstract: This invention relates to a communication network intended for secure transmission of speech and data, including different types of subscriber terminals (10-15) and switching modules (4-6), and where the network further comprise crypto devices to undertake encryption/decryption of information transmitted through the network. At least one of the crypto devices is constituted by a crypto-pool device (7,8,9) having a number of crypto modules (CM) physically separated from the switching modules (4,5,6). Each crypto-pool (7,8,9; 20) is provided with a managing device (MA, 26) for communicating with a ciphering key distribution authority through standardized communication protocols and distribute keys to the relevant CM through a control path (25) of the crypto-pool. Each crypto-pool has access to an authentication server (AS, 16; 41,43) providing a directory of security certificates necessary in the authentication process when initiating a network connection.