Server certificates provide more security on the Internet and serve to verify the identity of servers. A certificate is issued by official, trustworthy institutions. A certificate is not forgeable if a strong hash algorithm is used. In normal life a certificate is comparable with an identity card or a notarial certification. Similar to a passport, certificates also have a certain validity period. Certificates thus ensure secure data exchange and form an important basis of trust for operators, e.g. of online shops.