MODIFICATION OF DOT ALGORITHM ON PERMUTATION PROCESS TO IMPROVE SECURITY AGAINST DIFFERENTIAL CRYPTANALYSIS
The number of data breaches has increased significantly in recent times. Numerous cases have highlighted the importance of storing sensitive data in an encrypted state. Encryption can be implemented using block ciphers. Traditionally, block ciphers were designed to operate in environments with no...
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| Format: | Theses |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/84845 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | The number of data breaches has increased significantly in recent times. Numerous
cases have highlighted the importance of storing sensitive data in an encrypted
state. Encryption can be implemented using block ciphers. Traditionally, block
ciphers were designed to operate in environments with no limitation on
computational resources, but the focus has now shifted towards lightweight block
ciphers (LWBC). LWBCs are computationally more efficient as they process
smaller data and key sizes compared to conventional block ciphers. Examples of
LWBC algorithms include PRESENT, PUFFIN2, DoT, and ACT. In addition to
providing a lightweight implementation, encryption algorithms must also ensure
security. An LWBC is considered secure if it is proven to be resistant to
cryptanalysis attacks. Although challenging and time-consuming, evaluating
algorithms through cryptanalysis is a crucial step in assessing the security of an
algorithm. An LWBC algorithm should at least demonstrate sufficient resistance
against basic cryptanalysis methods, such as differential cryptanalysis (Chan et al.,
2023). DoT is a lightweight block cipher with a 64-bit block size and a 128-bit key,
claimed to be resistant to differential cryptanalysis with a probability of 2
?70 (Patil
dkk., 2019). However, in 2022, Kumar demonstrated that the maximum differential
trail probability for DoT over 31 rounds is not 2
?70 but 2
?62
. Kumar (2022)
subsequently proposed MDoT as a modification of DoT. Although this represents
an improvement, the value still exceeds the security threshold of 2
?128. Therefore,
this research aims to further develop the DoT algorithm by replacing its
permutation layer with a 64-bit permutation using PRESENT, PUFFIN, and ACT
permutations. The research was conducted using the Design Science Research
Methodology (DSRM), which includes designing a modified algorithm, analyzing
the impact of algorithm components on differential cryptanalysis, reconstructing
Kumar’s (2022) work as a validation step, and evaluating the security of the
modified algorithm design against differential cryptanalysis. Based on the
evaluation, the differential trail for 31 rounds in DoTPRE and DoTPUF was found
to have a probability of 2
?93 with a total of 31 active S-boxes. Meanwhile, the
differential trail for 31 rounds in DoTACT had a probability of 2
?133 with a total
of 47 active S-boxes. Iterative patterns of one round were also found in the
differential trails of DoTPRE and DoTPUF, while no such pattern was found in
DoTACT. Based on these evaluation results, DoTACT provides the most significant
v
security improvement for DoT compared to the other two modifications. Therefore,
DoTACT is recommended as a modification of the DoT algorithm that can enhance
its security against differential cryptanalysis. |
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