Algoritem COMP128 na kartici SIM

Nunar, Anže (author), Žitnik, Arjana (mentor)

Kartica SIM igra pomembno vlogo pri mobilni komunikaciji. Na kartici SIM je shranjen zasebni ključ uporabnika. Do njega dostopa algoritem COMP128, ki omogoča avtentikacijo uporabnika v mobilno omrežje in generiranje sejnih ključev za šifriranje komunikacij. V diplomskem delu podrobno opišemo algoritem COMP128. Napad nanj izvedemo z grobo silo. Pri tem izkoristimo slabosti v strukturi algoritma COMP128 in paradoks rojstnega dne, kar omogoča rekonstrukcijo zasebnega ključa v realnem času. Napad smo tudi implementirali in preizkusili. V posebnem poglavju predstavimo uporabljene koncepte iz kriptografije. To so avtentikacija, zgoščevalne funkcije in paradoks rojstnega dne.

• Language: Slovenian
• Keywords: algoritem COMP128, avtentikacija, kartica SIM, kriptografija, napad z grobo silo, protokol GSM, paradoks rojstnega dne
• Work type: Bachelor thesis/paper
• Organization: FRI - Faculty of Computer and Information Science
• Year: 2015
• PID: 20.500.12556/RUL-72490
• COBISS.SI-ID: 1536612803
• Publication date in RUL: 24.09.2015

Secondary language

• Language: English
• Title: The COMP128 algorithm and the SIM card

Abstract

SIM card has an important role in mobile communications. It contains the user's private key, which is used in COMP128 algorithm for user authentication to the mobile network and generating session keys to encrypt communications. In this thesis a detailed description of COMP128 algorithm is presented. A brute force attack on the algorithm is described, which exploits a weakness in the structure of COMP128 algorithm, and is based on birthday paradox. As a result the user's private key can be obtained in real time. The attack on COMP128 algorithm was also implemented and tested. A separate chapter provides the necessary cryptographic concepts such as authentication, hash functions and birthday paradox.

• Keywords: COMP128 algorithm, authentication, SIM card, cryptography, brute-force attack, GSM protocol, birthday paradox