Aug 16, 2018

@Mlmikael I think what you're looking for is the max length of a DER encoded ECDSA signature, as used in bitcoin. I could be wrong, but don't think that's formally described anywhere (although there definitely are formal definitions of "DER encoding" and "ECDSA signatures", outside of the bitcoin sphere). If bitcoin made changes to how the signatures could be DER encoded, the length could vary more, but while it doesn't, there's a cap. In other words, if you wanted to be 'wasteful' and provide a buffer far larger than this max value, it shouldn't hurt anything, so long as you respect the actual encoding lengths of the format when working with the data. There are numerous posts about the length as used in bitcoin, such as the one you provided as well as this one: https://bitcoin.stackexchange.com/questions/77191/what-is-the-maximum-size-of-a-der-encoded-ecdsa-signature