Daniel Stadulis
Aug 22, 2017 · 1 min read

“Much like real life signatures, digital signatures can vary slightly and yet still be valid.”

This line might needlessly spook some people regarding the authenticity of bitcoin transactions. I think a easy to intuit, real-world example would be, the inverse image (i.e. the negative from a copy machine or film photo) of a physical signature still proves it’s valid. What’s going on in the background is that the piece of crypto that handles signatures uses a mathematical curve that’s symmetrical on one axis (Metaphor: It doesn’t matter if the signature is black ink on white paper or white ink on black paper) and therefore you can invert the value and flip the signature. Resulting in a signature that’s still valid/authentic but looks different. Bitcoin version 0.11 enforced one version of how this signature could exist (Black ink on white paper). https://en.bitcoin.it/wiki/Transaction_Malleability

https://github.com/bitcoin/bips/blob/master/bip-0066.mediawiki

https://blog.blockcypher.com/enforcing-low-s-values-to-eliminate-a-bitcoin-network-attack-3582fc0ae948

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    Daniel Stadulis

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