BIP 341: Fix taproot_tweak_pubkey #1386

pull jonasnick wants to merge 1 commits into bitcoin:master from jonasnick:fix-taproot-tweak-pubkey changing 1 files +4 −1

jonasnick commented at 8:44 PM on October 24, 2022: contributor

lift_x returns None if the input integer is not an X coordinate on the curve to indicate failure. point_add, on the other hand, interprets None as the point at infinity. Therefore, without this commit, if the internal pubkey is not a valid X coordinate, the function will not fail, which contradicts the specification in the "Script validation rules section". Instead, it sets Q to t*G.

A test vector is being added here: https://github.com/bitcoin-core/qa-assets/pull/98

CC @sipa @ajtowns

BIP 341: Fix taproot_tweak_pubkey

`lift_x` returns `None` if the input integer is not an X coordinate on the curve
to indicate failure. `point_add`, on the other hand, interprets `None` as the
point at infinity. Therefore, without this commit, if the internal `pubkey` is
not a valid X coordinate, the function will not fail, which contradicts the
specification in the "Script validation rules section". Instead, it sets `Q` to
`t*G`.

be340277fc

sipa commented at 6:12 PM on November 10, 2022: member

ACK be340277fcaa57a813a898700c1aef9637cfa90e
kallewoof merged this on Jan 4, 2023
kallewoof closed this on Jan 4, 2023

Contributors

jonasnick

sipa