Hi Andrew,
Thank you for your answer.
Initially I thought of transactions that do not contain OP_Checksig in
their script, but was not clear in my question.
(I even wrote that the sig is over the previous transaction which is wrong.)
I thought of, e.g., a transaction that can be spent if one can produce a
valid preimage of a hash
(https://en.bitcoin.it/wiki/Script#Transaction_puzzle)
But in the next paragraph on the link is written that this transaction
is insecure, since integrity is not guaranteed.
So I assume that there are no further mechanisms to guarantee integrity
of transactions besides OP_Checksig.
All the best
Henning
Am 12.04.2016 um 21:46 schrieb Andrew C via bitcoin-discuss:
Henning,
The signatures do actually guarantee the integrity of the current
transaction if sighash all is used (it is used by default). The
signature is actually the signature of the hash of the entire
transaction except for the other inputs. As you can see in the picture
that you linked to, the outputs, the previous output script, the
outpoints, and everything else in a transaction except for the other
inputs are included in the data hashed. If this is changed by anyone,
the hash will no longer match and the signature is no longer valid. This
is how transactions are prevented from being modified.
Andrew
On 4/12/2016 10:03 AM, Henning Kopp via bitcoin-discuss wrote:
Hi all,
as far as i understand OP_Checksig is there to check authorization. It
guarantees that the creator of the transaction is authorized to spend
the funds of a previous transaction.
It does not guarantee integrity of the current transaction, since the
signature is over the outputs of the previous transaction
(modulo some gory details
https://en.bitcoin.it/w/images/en/7/70/Bitcoin_OpCheckSig_InDetail.png)
So there needs to be another mechanism for that. How does that work?
What prevents miners from modifying the txouts of unmined
transactions?
I assume this is also solved by signatures. Is the whole transaction
signed by the public key before relaying?
All the best
Henning
_______________________________________________
bitcoin-discuss mailing list
[email protected]
https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-discuss
_______________________________________________
bitcoin-discuss mailing list
[email protected]
https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-discuss
