Wernsdorf, Dr. Ralph

Ralph Wernsdorf studied mathematics of the Humboldt-University zu Berlin and got his degrees in 1980 (Diploma) and 1983 (PhD). He is an employee of Rohde & Schwarz SIT GmbH. Located in Berlin-Adlershof since 2002, the company develops and offers encryption solutions for secure communication in critical infrastructures. Examples can be seen in the figures: equipment which protects phone calls against eavesdropping and sensitive data during their transmission via public networks.

Dr. Wernsdorf has worked in several projects, studies and product developments in the area of IT-security. As »Head of Cryptology Fundamentals« he and his team have solved demanding mathematical and cryptographic tasks. Together with colleagues he has written a series of conference papers and other publications (for example for the Journal »Discrete Applied Mathematics«), mostly about algebraic properties of block ciphers.

Most of the known block ciphers are characterized by the successive application of so-called round functions. Each round function performs a reversible transformation (permutation) of the plain-text with the usage of a key-dependent parameter. Properties of the permutation group which is generated by these round functions can be important for the security of the encryption algorithm. If this permutation group is too small this can cause cryptographic weaknesses. For several known block ciphers (e.g. the Advanced Encryption Standard AES) it has been proven that the alternating group (a large permutation group) is generated.

left: TopSec Mobile – Voice encryption device for mobile phones
right: R&S© SITLine ETH Ethernet-Encrypter

Dr. Ralph Wernsdorf
ROHDE & SCHWARZ SIT GmbH
Am Studio 3
12489 Berlin, Germany
Telefon | Phone : +49 (0)30 6588 4222
ralph.wernsdorf@rohde-schwarz.com
www.sit.rohde-schwarz.com