Rectangle Attack Against Type‐I Generalized Feistel Structures

Type-I generalized Feistel networks (GFN) are widely used frameworks in symmetric-key primitive designs such as CAST-256 and Lesamnta. Different from the extensive studies focusing on specific block cipher instances, analysis against GFN structures gives generic security evaluation of basic concentrates more effect linear transformation. Currently, works this field mainly evaluate impossible differential attack, zero-correlation meet-in-the-middle attack yoyo game while its rectangle is still missing. In paper, we filled gap gave first structural analytical results attack. By exploiting properties, proved there exists a boomerang switch for time, which independent round functions. Then turned into chosen plaintext setting proposed new model. appending 1 beginning switch, constructed distinguisher key recovery could be performed.