FIGURE 27.
Bundle structure. Two Bitcoin UTXO transactions (top) and their corresponding IOTA bundles (bottom). Dashed edges denote trunk tips, whereas solid edges show branch edges. Tips of bundles (t 0, …, t 3) are past transactions that are unrelated to these IOTA bundles. We show trunk tips with dashed edges. The figure assumes that security level = 2 for addresses, which requires creating one zero‐value transaction (in gray color) to store the second fragment of each input address signature. For the third level, there would be two zero‐value transactions for each input address. We give bundle indices (e.g., 0/4) next to shapes. The left bundle has five transactions, whereas the right bundle has four