Questions tagged [quadratic-hashing]

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What is the O(n^2) signature hashing problem and how does SegWit solves it?

One of the many benefits of SegWit is that it solves the O(n^2) signature hashing problem. What exactly is the O(n^2) hashing problem and how segregating signatures to separate witness field solve it?
  • 7,018
3 votes
2 answers

Why is the signature hash different for each input in a multi-input transaction?

In pre-BIP143 signature hashes, I know that the signature hash differs because you have to substitute the previous scriptPubKey for each input and thus the serialization changes. The question is why? ...
  • 7,639
2 votes
1 answer

What causes quadratic hash problem?

I read ScriptSig content during signature (quadratic hashing) discussing quadratic hash problem. Quadratic hash problem is the issue that signing (or verifying) transaction time grows with the square ...
  • 1,202
5 votes
1 answer

ScriptSig content during signature (quadratic hashing)

As far as I know, the quadratic hashing problem came from the fact that every time a transaction is verified (or signed), the "unsigned transaction" that is hashed and verified changes depending on ...
  • 2,722
2 votes
2 answers

Which kinds of transactions show quadratic signature-hashing scaling?

It has been stated: A major problem with simple approaches to increasing the Bitcoin blocksize is that for certain transactions, signature-hashing scales quadratically rather than linearly. https:/...
  • 2,246
3 votes
2 answers

Quadratic hashing problem: Why not just create new OP code "CHECKSIG2" to fix?

Why can't "we" fix the quadratic hashing problem with OP_CHECKSIG with a soft fork? Update NO_OPx to OP_CHECKSIG2 with soft fork, where OP_CHECKSIG2 doesn't quadratically hash (uses a single tx hash ...
  • 4,696