Coincidentally, the kind of Merkle tree that Mark describes in his proposal is exactly the one that we use at Stampery. The Stampery BTA whitepaper[1] includes pseudocode for many of the algorithms outlined by this proposal, including fast-SHA256, the tree building process and the inclusion proving routine. The wording is slightly different but the logic is just the same, so I hope it helps future implementations in case of eventual adoption. [1] https://s3.amazonaws.com/stampery-cdn/docs/Stampery-BTA-v6-whitepaper.pdf Best, -- Adán Sánchez de Pedro Crespo CTO, Stampery Inc. San Francisco - Madrid T: +34 663 163 375