I assume you are asking about the scope of the MD5 hash, not the checksum. Because ZIP is a lossless compression algorithm, taking the hash of the whole ZIP archive (and checking it against the expected value) should provide identical "authenticity" information as checking the hash of each uncompressed internal file individually. If the ZIP archive hash matches the expected value, you don't even need to worry about the checksum values. The hash is a far more robust mechanism than the checksum.