At least in theory, the design of a block cipher is generally made more secure by: 11. increasing the number of rounds used in a block cipher, using a block cipher with a larger block size. (a) For each of these techniques, explain why it might be more secure (b) For each of these techniques, what are the associated practical disadvantages? (c) For each of these techniques, explain which of the three significant problems with ECB mode that we identified in Section 4.6.1 might be reduced (d) Explain why it is inadvisable to apply either of these techniques to a published (standardised) block cipher such as AES