How to Qualify Electronic Signatures and Time Stamps

摘要

In this work we will show how non-qualified electronic signatures and time stamps can be efficiently enhanced in order to equip them with similar features as qualified ones. In particular we will show how non-qualified electronic signatures can be used in business processes which require the written form. Furthermore we will show how to construct "interval-qualified" (IQ) time stamps which may serve as cost efficient alternative to qualified time stamps issued by a trusted authority. An IQ time stamp issued at time t_i is linked to two qualified time stamps issued at time T_1 and T_2, in a way that one is able to prove thatT_1 < T_i < T_2.