1998

Ahto Buldas, Peeter Laud. "New linking schemes for digital time-stamping", (pdf). In The 1st International Conference on Information Security and Cryptology, pages 3-14, Seoul, Korea, 18-19 December 1998. © by Korea Institute of Information Security and Cryptology.
Ahto Buldas, Peeter Laud, Helger Lipmaa, Jan Willemson, "Time-Stamping with Binary Linking Schemes." (pdf ) In Hugo Krawczyk, editor, Advances in Cryptology - CRYPTO '98, volume 1462 of Lecture Notes in Computer Science, pages 486-501. Springer-Verlag, 1998.
Helger Lipmaa. "IDEA: A cipher for multimedia architectures?" (pdf). In Stafford Tavares and Henk Meijer, editors, Selected Areas in Cryptography '98, volume 1556 of Lecture Notes in Computer Science, pages 248-263, Kingston, Canada, 17--18 August 1998. Springer-Verlag
Ahto Buldas, Helger Lipmaa, "Digital Signatures, Timestamps and the corresponding Infrastructure", (pdf). Küberneetika AS, Technical Report 1998-21, Jan 1998, 7 pages.