How are the unlocking script + locking script executed?

Question

I just wanted to verify the input of transaction 7de75. The related output is index 10 of transaction 00f64.

The locking script defined in 76a91 (index 10) is:

OP_DUP
OP_HASH160
7ddb236e7877d5040e2a59e4be544c65934e573a
OP_EQUALVERIFY
OP_CHECKSIG

The unlocking script in 7de75 is:

3045022100b7393ff959120e3ccb5284e3cf2eaa200235643a1549a4e6faaa911619089e2b02207b677827c7beeb53503e016a8dd29164d07cb79f0f1e058df9b8dfa3568d029001
04c4b7a7f7bb2c899f4aeab75b41567c040ae79506d43ee72f650c95b6319e47402f0ba88d1c5a294d075885442679dc24882ea37c31e0dbc82cfd51ed185d7e94

I've concatenated both:

3045022100b7393ff959120e3ccb5284e3cf2eaa200235643a1549a4e6faaa911619089e2b02207b677827c7beeb53503e016a8dd29164d07cb79f0f1e058df9b8dfa3568d029001
04c4b7a7f7bb2c899f4aeab75b41567c040ae79506d43ee72f650c95b6319e47402f0ba88d1c5a294d075885442679dc24882ea37c31e0dbc82cfd51ed185d7e94
OP_DUP
OP_HASH160
7ddb236e7877d5040e2a59e4be544c65934e573a
OP_EQUALVERIFY
OP_CHECKSIG

and executed it via bitcoinIDE. However, OP_EQUALVERIFY failed. Could somebody explain to me where I made a mistake?

edit: I think Rene Pickhard explains the issue here but I cannot follow the explanation 😅

Answer 1

This appears to be a bug in BitcoinIDE. The issue is that it is computing the hash differently from what it actually is. Because it finds a different hash, the comparison that checks that the hashes match (the OP_EQUALVERIFY) fails.

However the hash does match. If you compute the hash manually, you get a different hash than what BitcoinIDE is showing.

Using the btcdeb project, I am able to execute this script and step through all of the opcodes correctly.