Final answer:
The block size for FORK256 is not well-known and cannot be specified without official documentation or reference to cryptographic standards. Common block sizes in cryptography are 128 bits and 256 bits, but without more information, it's impossible to determine the block size for FORK256.
Step-by-step explanation:
The size of the block used by FORK256 is not directly specified in well-known cryptographic standards. In the context of cryptographic algorithms, block sizes such as 128 bits (16 bytes) and 256 bits (32 bytes) are common, as seen in AES (Advanced Encryption Standard). FORK256, with its name potentially implying a 256-bit focus, might suggest a block size related to 256 bits. However, without specific documentation or standards referencing FORK256, the exact block size cannot be accurately stated. To respond correctly, one would need to refer to the formal definition and technical documentation for FORK256.