To modify Blowfish for larger block sizes, we’d need to adjust the Feistel network and S-boxes. The current 16-round Feistel structure could be increased proportionally with the block size. However, this would require more computational resources, potentially impacting efficiency. To mitigate this, a balanced approach of increasing rounds and optimizing operations within each round should be considered.
The S-boxes in Blowfish are crucial for its security. For larger blocks, we’d need more S-boxes or larger ones. But simply scaling up may introduce vulnerabilities if not done carefully. A possible solution is to generate new S-boxes using secure pseudorandom number generators (PRNGs), ensuring unpredictability and resistance against cryptanalysis.
Lastly, key schedule algorithm must also be modified to accommodate changes in block size and S-boxes. It’s important that these modifications don’t compromise the diffusion and confusion properties of Blowfish.
