user81435: Please explain something about OP_RETURN to me?
https://bitcointalk.org/index.php?topic=1166928.0
I saw a discussion that the contents of OP_RETURN can open the value of access to the private key. I am not good at client scripting language. But I assume this is something related to the values of RawTX (R, S) where, when summing the additional value, you can calculate the value of X (that is, the private key). Am I right or wrong?

user7272: The method described in the post has nothing to to with OP_RETURN, but is concerned with the SIGOP limits in a block.
Each block has a limit on the number of SIGOPs that can be present in transactions in that block. Signature validation is a CPU intensive operation, and the limit exists to ensure that no block gets too big to validate on regular hardware.
The post describes how a single transaction can be made to consume up to 225 SIGOPS fairly trivially, limiting the number of such transactions in a block to 88. These utxos can be redeemed to any regular output, or an OP_RETURN.
Note that the post is from 2015, and the activation of segwit has increased the total SIGOPs allowed by a factor of 4, so this attack could cost more now.

81435: <p>Please explain something about OP_RETURN to me?
<a href="https://bitcointalk.org/index.php?topic=1166928.0" rel="nofollow noreferrer">https://bitcointalk.org/index.php?topic=1166928.0</a></p>

<p>I saw a discussion that the contents of OP_RETURN can open the value of access to the private key. I am not good at client scripting language. But I assume this is something related to the values of RawTX (R, S) where, when summing the additional value, you can calculate the value of X (that is, the private key). Am I right or wrong?</p>
 7272: <p>The method described in the post has nothing to to with OP_RETURN, but is concerned with the SIGOP limits in a block.</p>

<p>Each block has a limit on the number of SIGOPs that can be present in transactions in that block. Signature validation is a CPU intensive operation, and the limit exists to ensure that no block gets too big to validate on regular hardware.</p>

<p>The post describes how a single transaction can be made to consume up to 225 SIGOPS fairly trivially, limiting the number of such transactions in a block to 88. These utxos can be redeemed to any regular output, or an OP_RETURN.</p>

<p>Note that the post is from 2015, and the activation of segwit has increased the total SIGOPs allowed by a factor of 4, so this attack could cost more now.</p>
