Risk Assessment of the 3Des in ERTMS

The three-key Triple Data Encryption Algorithm (Triple Data Encryption Algorithm is also known in the literature as Triple-Des, or Triple DEA or TDEA) (3Des) is a symmetric encryption algorithm currently used in the European Traffic Management System (ERTMS) for integrity and authentication purposes. In a recent publication [1], 3Des has been withdrawn in favour of Advanced Encryption Standard (AES) [2] (The National Institute for Science and Technology (NIST) standard [1] allows to both algorithms can be used for specific purposes until 2030 with the intention of gradually phasing out 3Des towards AES). In this paper, we have investigated, from a practical point of view, known attacks to 3Des and proved that, in order to carry out such attacks, a disproportionate amount of hardware and money would be necessary. In practical terms this means that these attacks do not represent a realistic risk.