International Association
for Cryptologic Research

Over a decade, cryptographers are more attentive on designing lightweight ciphers in focus to compact cryptographic devices. More often, the security of these algorithms are defined in terms of its resistance to mathematical cryptanalysis methods. Nevertheless, designers are well aware of implementation attacks and concentrating on new design strategies to improve the defence quality against implementation attack. \\texttt{PRINCE}~\\cite{Julia2012} and \\texttt{RECTANGLE}~\\cite{cryptoeprint:2014:084} lightweight block ciphers are designed using new design strategies for efficiency and security. In this paper we analyse the security of \\texttt{PRINCE} and \\texttt{RECTANGLE} against a type of implementation attack called Differential Power Analysis (DPA) attack. Our attack reduces key search space from $2^{128}$ to $33008$ for \\texttt{PRINCE} and $2^{80}$ to $288$ for \\texttt{RECTANGLE}. To the best of our knowledge, this is the first DPA attack on \\texttt{PRINCE} and \\texttt{RECTANGLE}.