Sorry for my English, again...
First I wanted to place this post on Etherium Reddit, if it needs to be there, just close this question...

I need to implement this logic:

1. From Wallet 1 user sends to Smart Contract 1000 Ether, by calling function in Smart Contract.
2. Smart Contract holds 1000 Ether until some external event will not occur. Smart Contract checks this by polling information from external API. If this event not occurs a two days e.g. Smart Contract revert Ether.
3. Smart Contract sends 1000 Ether to Wallet 2 (if the condition of the previous paragraph is successful).

But I need do this for users who can`t have blockchain ("Etherium Wallet" app e.g.) on own computers.

And here's the next image...

1. Standart authentication - Login/Pass, OAuth, not important...
2. We identified the user credentials and associate it with a particular Wallet Account (0x123...).
3. Now we sends commands to the Geth with using Wallet Account of the previous paragraph.
4. Finally, end-user has a limited set of possibilities by using UI in own application.

It's okay to do this server-side layer, and do some authentication?