A network device represents a user having a predefined associated password, a predefined associated symmetric crypto-key and a predefined associated asymmetric crypto-key, including a first private key portion, a second private key portion and a public key portion. The device includes a memory, input device and processor. The memory stores a function. The input device allows the inputting of the user password. The processor operates in either a first or second mode of operation. In the first mode of operation, the processor processes the input password in accordance with the stored function to generate the associated first private key portion, and encrypts and/or decrypts or signs a message with the generated first private key portion. In a second mode of operation, the processor processes the input password in accordance with the same stored function to generate the associated symmetric crypto-key, and encrypts and/or decrypts and/or authenticates a message with the generated symmetric crypto-key.