Algorithms

An encryption algorithm is a mathematical procedure used to encrypt data. Through the use of an algorithm and a key, information is encoded into cipher text and requires the use of a 'key' to transform the data back into its original form.

Algorithms are an essential part of a technology to ensure effective and secure authentication, as well as to provide integrity and encryption. ETSI creates cryptographic algorithms and protocols specific to fraud prevention, unauthorized access to public and private telecommunications networks and user data privacy.

ETSI is custodian of these algorithms, as well as algorithms produced by other organizations. We are also custodians of other codes and test suites.

Download the DVB CSA3 algorithm technology leaflet

ETSI Security Algorithms Group of Experts (SAGE) provides standards makers with cryptographic algorithms and protocols specific to fraud prevention, unauthorized access to public and private telecommunications networks and user data privacy.

The group's output includes algorithms for audiovisual services, 3GPP^TM, DECT^TM, GSM^TM, TETRA, GPRS and Universal Personal Telecommunications (UPT). Where appropriate, the group collaborates with other ETSI committees and with other organizations in order to ensure that the algorithms produced fully meet the needs of the technologies and services in which they are used.

Mobile communications

For example, working with the 3GPP^TM Organizational Partners, SAGE has produced the A5/3 encryption algorithms for GSM and EDGE (Enhanced Data rates for GSM Evolution), and the GEA3 algorithm for the General Packet Radio Service, GPRS.

SAGE is also responsible for the specification of the Milenage algorithm set, an example algorithm set for the 3GPP^TM authentication and key generation functions f1, f1*, f2, f3, f4, f5 and f5*, which was developed for 3rd Generation mobile communications (UMTS^TM).

SAGE has also developed the security algorithms for the UMTS^TM radio interface (UTRA) - UEA1 and UIA1 - in collaboration with the 3GPP^TM Organizational Partners. UEA1 is the standard encryption algorithm, and UIA1 is the standard integrity algorithm; both are based on the Kasumi block cipher, also designed by SAGE (as a variation of Mitsubishi's MISTY1 algorithm).

Whilst the algorithms are considered to be extremely robust, there is always a need to have alternative solutions ready should a breach of security ever occur. For this reason, SAGE has recently produced alternatives to the Kasumi-based algorithms for UTRA, known as UEA2 and UIA2.

ETSI Technical Report TR 133 908 (or 3GPP^TM TR 33.908) provides an overview of the algorithm mechanisms in UMTS.

ETSI's custodian role

Implementation of the various algorithms is generally subject to a licence which, among things, restricts their utilisation to the telecommunications equipment or service for which they have been designed.

ETSI acts as a custodian for the algorithms developed by SAGE, as well as other codes and algorithms, and is responsible for the distribution and licensing of the confidential information and documents.