user24902: In step 5 of the procedure described in https://en.bitcoin.it/wiki/Smart_Property#Theory, the buyer creates a partially signed transaction. Will the seller be able to change an output prior to signing and broadcasting - and thus returning the token to an output he may redeem himself?

user12983: In one word: no. Changing tx output after signing makes existing signature invalid.
( There are some special cases, like signature hash type SIGHASH_SINGLE or SIGHASH_NONE, but we assume that the buyer uses correct signing SIGHASH_ALL )

24902: <p>In step 5 of the procedure described in <a href="https://en.bitcoin.it/wiki/Smart_Property#Theory" rel="nofollow">https://en.bitcoin.it/wiki/Smart_Property#Theory</a>, the buyer creates a partially signed transaction. Will the seller be able to change an output prior to signing and broadcasting - and thus returning the token to an output he may redeem himself?</p>
 12983: <p>In one word: <strong>no</strong>. Changing tx output after signing makes existing signature invalid.</p>

<p>( There are some special cases, like signature hash type SIGHASH_SINGLE or SIGHASH_NONE, but we assume that the buyer uses correct signing SIGHASH_ALL )</p>
