Conditional Cube Attack on Round-Reduced River Keyak

This paper evaluates the security level of the River Keyak against the cube-like attack. River Keyak is the only lightweight scheme of the Keccak-permutation-based Authenticated Encryption Cipher Keyak, which is one of the 16 survivors of the 3rd round CAESAR competition. Dinur et al. gave the seven-round cube-like attack on Lake Keyak (1600-bit) using the divide-and-conquer method at EUROCRYPT 2015, then Huang et al. improved the result to 8-round using a new conditional cube attack at EUROCRYPT 2017. While for River Keyak, the 800-bit state is so small that the equivalent key (256-bit capacity) occupy double lanes, the attacks can not be applied to the River Keyak trivially. In this paper, we comprehensively explore the conditional cube attack on the small state (800-bit) River Keyak. Firstly, we find a new conditional cube variable which has a much weaker diffusion than Huang et al.\u27s, this makes the conditional cube attack possible for small state (800-bit) River Keyak. Then we find enough cube variables for 6/7-round River Keyak and successfully launch the key recovery attacks on 6/7-round River Keyak with the time complexity $2^{33}$ and $2^{49}$ respectively. We also verify the 6 and 7-round attack on a laptop. Finally, by using linear structure technique with our new conditional cube variable, we greatly increase the freedom degree to find more cube variables for conditional cube attacks as it is complex for 800-bit state to find enough cube variables for 8-round attack. And then we use the new variables by this new method to launch 8-round conditional cube attack with the time complexity $2^{81}$. These are the first cryptanalysis results on round-reduced River Keyak. Our attacks do not threaten the full-round (12) River Keyak

MILP-aided Cube-attack-like Cryptanalysis on Keccak Keyed Modes

Cube-attack-like cryptanalysis was proposed by Dinur et al. at EUROCRYPT 2015, which recovers the key of Keccak keyed modes in a divide-and-conquer manner. In their attack, one selects cube variables manually, which leads to more key bits involved in the key-recovery attack, so the complexity is too high unnecessarily. In this paper, we introduce a new MILP model and make the cube attacks better on the Keccak keyed modes. Using this new MILP tool, we find the optimal cube variables for Keccak-MAC, Keyak and Ketje, which makes that a minimum number of key bits are involved in the key-recovery attack. For example, when the capacity is 256, we find a new 32-dimension cube for Keccak-MAC that involves only 18 key bits instead of Dinur et al.\u27s 64 bits and the complexity of the 6-round attack is reduced to $2^{42}$ from $2^{66}$. More impressively, using this new tool, we give the very first 7-round key-recovery attack on Keccak-MAC-512. We get the 8-round key-recovery attacks on Lake Keyak in nonce-respected setting. In addition, we get the best attacks on Ketje Major/Minor. For Ketje Major, when the length of nonce is 9 lanes, we could improve the best previous 6-round attack to 7-round. Our attacks do not threaten the full-round (12) Keyak/Ketje or the full-round (24) Keccak-MAC. When comparing with Huang et al.\u27s conditional cube attack, the MILP-aided cube-attack-like cryptanalysis has larger effective range and gets the best results on the Keccak keyed variants with relatively smaller number of degrees of freedom

Security and Privacy for Modern Wireless Communication Systems

The aim of this reprint focuses on the latest protocol research, software/hardware development and implementation, and system architecture design in addressing emerging security and privacy issues for modern wireless communication networks. Relevant topics include, but are not limited to, the following: deep-learning-based security and privacy design; covert communications; information-theoretical foundations for advanced security and privacy techniques; lightweight cryptography for power constrained networks; physical layer key generation; prototypes and testbeds for security and privacy solutions; encryption and decryption algorithm for low-latency constrained networks; security protocols for modern wireless communication networks; network intrusion detection; physical layer design with security consideration; anonymity in data transmission; vulnerabilities in security and privacy in modern wireless communication networks; challenges of security and privacy in node–edge–cloud computation; security and privacy design for low-power wide-area IoT networks; security and privacy design for vehicle networks; security and privacy design for underwater communications networks