Use low 's' values for signatures. #24
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richardkiss
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Apr 20, 2014
Use low 's' values for signatures.
ghtdak
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Jul 16, 2016
Use low 's' values for signatures. [gitreformat yapf-ify (github/ghtdak) on Fri Jul 15 12:50:05 2016] [from commit: 3d38d6b]
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As per https://github.com/bitcoin/bips/blob/master/bip-0062.mediawiki#low-s-values-in-signatures, using values of
sbounded bycurve.order()/2can help preventing transaction malleability, by making sure no one other than sender can make different signatures for the same transaction. Combined with additional bitcoind validation to be implemented for transactions withnVersion=3it prevents issues with transactions modified by third parties otherwise not having control over them.This change enables this "low S values" behaviour by default in pycoin, without any additional configuration. I think it is important step for compatibility with
nVersion=3and is a good idea to always do it, because there are no counterindications for it AFAICS.