Say I want to hide a PDF file "A". I have with me a picture of a cat "B". I want software which can take both files as input and "encrypt" them to form "C" in some way such that:
If someone asks me to supply the password for the file "C" (say under coercion) I can say password "1" which will cause the file to decrypt to give the cat picture "B".
If I want to access the file "A", I use a different password "2" to decrypt the same file "C" to "A" (and optionally "B").
Is this possible? And is it obvious from analysing the encrypted file that it's not just a encrypted cat picture?
For OS X and/or Windows.