ABSTRAKSI: Keamanan sistem pada jaringan GSM (Global System for Mobile Communication) sangat diperlukan untuk menghindari adanya pencurian informasi oleh pihak atau badan yang tidak bertanggung jawab. Keamanan sistem pada jaringan GSM diimplementasikan berupa metode kriptografi algoritma A5 yang merupakan metode penyandian suara pada saat komunikasi secara real time antara MS (Mobile Station) dan BS (Base Station).
Algoritma A5/1 merupakan algoritma A5 versi kuat pada jaringan GSM yang merupakan algoritma kriptografi simetris dengan teknik enkripsi stream chiper yang terdiri dari 3 buah LFSR (Linier Feedback Shift Register) dengan derajat 19,22, dan 23, dimana LFSR adalah register geser dengan umpan balik linier yang merupakan pembangkit deretan bilangan acak. Sedangkan TMS320VC33 ialah DSP (Digital Signal Processor’s) Card yg mempunyai kecepatan operasi hingga 75 MIPS (Million Instruction Operations per Second) atau 13,34 ns per instruksi yang memungkinkan pengolahan sinyal digital secara real time. Tugas akhir secara khusus membahas perancangan dan implementasi kriptografi algoritma A5/1 menggunakan DSP Card TMS320VC33 dimana paramater yang dianalisis ialah Time Processing, Avalanche Effect,Brute Forced Attack dan Variance.
Dari hasil pengujian dapat disimpulkan bahwa sistem dapat direalisasikan dengan waktu proses 2,607516 ms yang dihitung berdasarkan duty cycle. Nilai avalanche effect berdasarkan perubahan 1 bit kunci mencapai 45,39473% sedangkan berdasarkan perubahan 1 bit plaintext atau ciphertext hanya 0,893%. Besarnya nilai variance 6,0982 sedangkan waktu untuk melakukan brute forced attack ialah 1,406791788 x 1028 tahun.Kata Kunci : A5/1 Algorithm, DSP Card TMS320VC33, GSM (Global System for Mobile Communication), Time Processing, Avalanche Effect, Variance, Brute Forced AttackABSTRACT: Security system in GSM network (Global System for Mobile Communication) is necessarily needed to avoid the information robbing by the others side or groups who are not responsible. Security system in GSM network is implemented in A5 algorithm of cryptography method, which is a voice coding method in real time communication, goes on between MS (Mobile Station) and BS (Base Station).
A5/1 method is a fervent version of A5 Algorithm in GSM networks that symmetric cryptography algorithm with stream chiper encryption technique which consists of 3 LFSR (Linier Feedback Shift Register) in 19, 22 and 23 degree. LFSR is a linier back forward shift register as a line of random numbers. While TMS320VC33 is DSP (Digital Signal Processor’s) Card which has operation velocity reaches 75 MIPS (Million Instruction Operations per Second) or 13.34 ns per instruction, there are probabilities for doing digital signal processing in real time. This final task specially discusses about planning and implementing of A5/1 algorithm cryptography uses TMS320VC33 DSP Card where the parameters have analyzed, such as time processing, avalanche effect, brute forced attack and variance.
From the tested results have made a conclusion that system can be realized with processing time is 2.607516 ms which calculated based on duty cycle. Value of avalanche effect based on changing of 1 key bit reaches 45.39473%, while based on changing of 1 plaintext bit or ciphertext only 0.893%. Variance value is 6.0982, while time to brute forced attack is 1.406791788 x 1028 year.Keyword: A5/1 Algorithm, DSP Card TMS320VC33, GSM (Global System for Mobile Communication), Time Processing, Avalanche Effect, Variance, Brute Forced Attack