[RFC] Detecting Malled Transactions

[phelix]

from https://gist.github.com/sipa/8907691

1. Inherent ECDSA signature malleability
2. Non-DER encoded ECDSA signatures
3.-8. [Txin script altering stuff]

Non-malled:
1.) Rule: lower half S is better
(does the standard client or any other client produce differing signatures?)
2.) Rule: only DER, handled as of 0.8+
3.-8.) Rule: shorter tx_in script is better

edit: How to find malled tx in the first place? Use NTXID: https://github.com/bitcoin/bitcoin/pull/3656