Pengukuran level keamanan sebuah algoritma block cipher dapat dilakukan dengan 2 (dua) cara, yaitu melakukan pengujian pemetaan fungsi acak secara teoritis berdasarkan sifat matematis dan statistik, serta melakukan serangan berdasarkan karakteristik komponen, dan struktur dari algoritma block cipher tersebut. Serangan terhadap algoritma block cipher yang umum dilakukan adalah Differential Attack dan Linear Attack. Pada penelitian ini akan dilakukan analisis dengan menggunakan differential attack terhadap algoritma PRESENT. Differential attack merupakan serangan atau teknik kripanalisis yang termasuk ke dalam asumsi chosen-plaintext attack. Serangan ini akan diterapkan pada 5 round, 10 round, dan 15 round dan pada 1 byte, 2 byte, dan 3 byte aktif berdasarkan karakteristik sbox dan pbox algoritma PRESENT. Hasil pada penelitian ini akan menunjukkan bahwa differential attack pada algoritma PRESENT 5 round dan10 round lebih baik dibandingkan dengan menerapkan serangan praktis seperti brute force attack, sedangkan pada algoritma PRESENT 15 round differential attack akan tidak lebih efektif jika dibandingkan dengan brute force attack. Oleh karena itu dapat dikatakan bahwa algoritma PRESENT tahan terhadap differential attack untuk > 15 round.

Measuring security level from a block cipher algorithm could be done by two methods, first method is conducting random testing of mapping functions base on mathematics and statistic properties, while the second method is attacking the algorithm base on its components and structure characteristics. Common attack that used to be done in block cipher algorithm are differential attack and linear attack. This paper would analyze PRESENT algoritm with differential attack. Differential attack is an attack or cryptanalysis technique which belong to the chosen-plaintext attack type of attacks. This attack would be applied into 5 round, 10 round, and 15 round, 1 byte, 2 byte, 3 byte active base on sbox and pbox characteristics of the PRESENT algorithm. The result of this paper would show that differential attack on 5 round and 10 round of PRESENT algorithm is better than applying practical attack like brute force attack, while differential attack on 15 round of PRESENT algorithm is not more effective than brute force attack. Therefore we could state that PRESENT algorithm would resistant to differential attack for more than 15 round.

Keywords: Differential attack; block cipher; algoritma PRESENT.