Final answer:
The statement about larger block sizes, key sizes, and more rounds increasing security is false because it oversimplifies the complex nature of encryption. Security in cryptography is influenced by various factors and simply increasing sizes or rounds does not guarantee better security.
Step-by-step explanation:
The statement 'Larger block sizes increase security. Larger key sizes increase security. If the round function is secure, then more rounds increase security.' can be characterized as false as a blanket statement. While larger block sizes and key sizes can potentially increase security by making it more difficult for unauthorized parties to decrypt the content without the correct key, it is not a guarantee in every context and must be balanced with considerations for performance and practicality. Similarly, while more rounds in an encryption algorithm's round function can add complexity and therefore increase cryptography security, if the round function has inherent vulnerabilities, simply increasing the number of rounds will not improve security. Encryption is a nuanced field where various factors contribute to the overall security of a system.