The e-Government implementation demands a higher level of security than other web-based services. The PKI (Public Key Infrastructure) meets the demands of authentication, integrity and non-repudiation, becoming a common place for all web-based transactions. Using the digital certificates, citizens can make use of the newest ways of public service delivering. As G2C interactions are progressing rapidly, the G2G transactions have to find an acceptable way to benefit from the PKI technologies, adopting the best trust path in digital certification. The objective of this study is to propose Peer-to-Peer and Bridge CA cross-certification models for the digital certification of public administration authorities. Based on the prior work in the field of e-Government, the PKI implementation has proved to be more openly accepted in the G2C relations, and the digital certification is widely used by the private sector. The observation of the trust path led us to conclude that the main concern is that the digital certification should not be hierarchically constructed, as long as the Supervision and Regulation Authority, represented by the Ministry of Communication and Information Society of Romania is not in an hierarchical relation with other public administration authorities.