LONDON – Online whistle-blower WikiLeaks has posted a huge encrypted file named "Insurance" to its website, sparking speculation that those behind the organization may be prepared to release more classified information if authorities interfere with them. At 1.4 gigabytes, the file is 20 times larger than the batch of 77,000 secret U.S. military documents about Afghanistan that WikiLeaks dumped onto the Web last month, and cryptographers say that the file is virtually impossible to crack — unless WikiLeaks releases the key used to encode the material.