Hawala is an old indian/middle east , money transaction system , based on mutual trust, and uses an encryption system based on spoken keycodes.How is it similar to bitcoin transaction system?
The major difference is, while Hawala means trust, Bitcoin does not depend on trust. Everything is made of cryptographical signatures, making it 100%** safe, while Hawala cannot / may not be trusted.
** Two exceptions: 1) Majority of hashrate is attacking the network. See this 2) The theoretically possible, but practically impossible hash collisions. It doesn't happens, while the theoretical safety isn't 100%, rather 99.999999999...%