Interesting project, Kristov. Two more ideas for fuzzing bitcoin txs:
- random bit flipping from valid txs
- random tx script generators:
  - from a grammar
  - from a stochastic grammar
  - from a random sequence of opcodes

I've made some really small experiments on fuzzing in the past [1][2], and
I'm interested in helping out.

Best,
Manuel

[1] https://github.com/maraoz/json-fuzzer
[2] https://github.com/maraoz/bitcoin-fuzzer

On Tue, Sep 1, 2015 at 3:03 PM, Wladimir J. van der Laan via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> On Tue, Sep 01, 2015 at 04:59:15PM +0000, Monarch via bitcoin-dev wrote:
>
> > which uses Bitcoin Core for validation.  If they aren't validating
> > transactions before broadcast they won't make it more than a single
> > hop through the P2P the network so they are of minimum concern.
>
> blockchain.info had some problems here for a while. They were not using a
> full validating node underneath:
>
> - Signatures were not verified properly. This resulted in some panic when
> it looked like (on their site) a massive number of very old coins were
> being spent.
>
> - They were relaying loose coinbase transactions. This caused them to be
> instantly banned from nodes they were connected to.
>
> So there's certainly some scope for fun with fuzzing those APIs.
>
> Wladimir
>
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