How does SHA-3 process message blocks?

The SHA-3 hashing algorithm processes message blocks by XORing them into the initial bits of the state. This method is critical to the way SHA-3 operates, as it utilizes a sponge construction, which absorbs input data into its state through a series of permutations and absorbing steps.

In this process, data is taken in fixed-size blocks and combined with the internal state of the sponge using the XOR operation. This ensures that the data is integrated into the existing state, allowing for a strong mixing of the input and maintaining the integrity of the overall hash. The use of XOR helps in maintaining diffusion in the hashing process, where changes to the input data lead to large differences in the output hash.

This method is distinct from options that suggest direct encryption or splitting data into parts without highlighting the importance of state interaction, which would not represent the unique operation of SHA-3 properly. The sponge construction and the XOR step are fundamental to the strength and versatility of SHA-3 as a hashing algorithm.