Trusted third parties:

1. Those who wrote the encryption and understand the math (very small %).

2. Those who write the software powering the blockchain (small %)

3. Those who write the wallet software you use to use the blockchain (small %)

4. Those who build the software you use on the same platform you use your wallet.

5. The operating system you use implementing all of the above.

6. The hardware you use implementing all of the above.

Yeah, tons of no trust....