Thos paper summarized previously proposed several public key distribution systems and proposes a new public key distribution system to generate an common secret conference key for public key distribution systems three or more user. The now system is based on discrete exponentiation, that is all operations involve reduction modulo p for large prime p and we study some novel characteristics for computins multiplicative inverse in GF(p). We use one-way communication to distribute work keys, while the other uses two-way communication. The security of the new system is based on the difficulty of determining logarithms in a finite field GF(p) and stronger than Diffie-Hellman public key distribution system.