It is possible to encrypt something without having a backdoor, in fact it's reasonably simple,
I don't know why companies just don't do it. I made a very simple encryption program in QBasic once,it just asked for a password and added each letter in the pass word togeather, then made a hash key by setting the random number seed to that value then adding each byte of the file to the next random number plus a byte value of a charicter in the password (a different one each time). Bingo the file just looks like random data and there's no way of decrypting it without the password and I'm no genius.