How do I know if its encrypted?

[Eric Hughes]

   From: Ben.Goren at asu.edu

   Here's a solution:

What problem, pray tell, does this solve?  It seems far more
complicated than it need be.

   Alice sends a file to Dave's DataHaven. When Alice wants her file back, she
   sends to Dave a secure hash of the file, a key with which to decrypt it,
   and a handful of plaintext at the beginning of the file. Dave decrypts the
   file that matches the hash with the key Alice gave him; if the file begins
   as Alice says it should, Dave returns the file to Alice.

Eric