Lock funds in transaction A until transaction B?

[andrewdb]

I am learning about Bitcoin script, and wondering if something like the following is possible:

Is there a way to create a transaction which will lock funds until another transaction from someone else with a certain metadata exists?

[achow101]

I am learning about Bitcoin script, and wondering if something like the following is possible:

Is there a way to create a transaction which will lock funds until another transaction from someone else with a certain metadata exists?

You cannot lock them until a certain transaction exists. However, what you can do is have a script can only be spent from when a certain secret is known. That secret could be published in another transaction.

You can also lock to a certain date or block height.

[andrewdb]

You cannot lock them until a certain transaction exists. However, what you can do is have a script can only be spent from when a certain secret is known. That secret could be published in another transaction.

Interesting.

Which opcodes are involved in this "lock-until-secret-published" strategy? Is this P2SH?

I'd love to learn more about this.

[achow101]

You cannot lock them until a certain transaction exists. However, what you can do is have a script can only be spent from when a certain secret is known. That secret could be published in another transaction.

Interesting.

Which opcodes are involved in this "lock-until-secret-published" strategy? Is this P2SH?

I'd love to learn more about this.

The address to lock the coins in is a p2sh address.

The script itself may look something like:

Code:

OP_SHA256 <sha256(secret)> OP_EQUALVERIFY
<pubkey> OP_CHECKSIG

This would mean that the person who is spending it must own the private key for the <pubkey> and must know the secret so that when the secret is put through the SHA256 hash, you get <sha256(secret)>.