This sounds like a case of crypto nerd's fantasy: http://xkcd.com/538/ http://xkcd.com/538/ In theory... Judge: "The SHA1 hash in the bank transfer dated 1 Ja

This sounds like a case of crypto nerd's fantasy: http://xkcd.com/538/ http://xkcd.com/538/ In theory... Judge: "The SHA1 hash in the bank transfer dated 1 Jan matches the hash I calculated for the document you supplied me, so you must have had access to the document on 1 Jan. I believe you" In reality... Judge: "Wait, you sent an e-mail with this document on 1 January?" You: "Sure, here's my gmail account. See this screenshot" Judge: "Well, that sorts it"