LBlock分组密码代数旁路攻击

Algebraic side-channel attack on LBlock

对轻型分组密码LBlock抗代数旁路攻击安全性进行了评估.给出了LBlock密码算法的代数方程表示方法,使用示波器采集微控制器ATMEGA324P上的LBlock实现功耗泄露,利用泊松相关系数方法推断加密中间状态汉明重,基于可满足性问题并转化为代数方程组,同LBlock密码算法代数方程联立,最后使用CryptoMinisat解析器进行方程组求解,成功恢复加密密钥.实验结果表明:微控制器上的LBlock实现易遭受代数旁路攻击,仅需一条功耗曲线,已知明密文下的3轮汉明重泄露、未知明密文条件下6轮汉明重泄露分别经2.4s和0.4s分析即可恢复80bit完整密钥.

The security of LBlock, a lightweight block cipher against the algebraic side-channel attack （ASCA） was evaluated. Firstly, the algebraic representation of LBlock was given. Then, the power leakages of LBlock on ATMEGA324P microcontroller were measured by a digital oscilloscope, and some leakage points with obvious power patterns were chosen as the targeted points and used to de- duce the Hamming weights via computing the Pearson correlation factor. The satisfiability-based method was chosen to representing Hamming weights with algebraic equations and combining with al- gebraic equations of LBlock. Finally, the CryptoMinisat solver was applied to solve for the key. Ex- periment results demonstrate that LBlock is vulnerable to ASCA, and full 80 bit master key of LBlock can be derived via analyzing the HW leakages of the first 3 rounds and 6 rounds in a single power trace with 2.4 s and 0.4 s under known and unknown plaintext/ciphertext scenario respectively.