To ensure the security of authentication and key distribution in the space information network, this paper proposes a public-key management scheme based on the elliptic curve cryptosystem. With the capacity for network access authentication and key agreement/update, this scheme can achieve various security goals, such as authenticity, anti-replay, and forward/backward security. For interstellar authentication and key agreement, our scheme only requires 3 interactions between the satellites. We provide a security and efficiency analysis for our scheme, and show that the proposed scheme not only satisfies the actual availability in the space information network, but also performs better than other existing public-key management schemes.