“…We find that most works ensure the confidentiality of the raw training data, but do not consider the leakage that might occur from computations required for collaborative tree induction, e.g., comparison operations are performed on cleartext data to abide with HE limitations. To this end, we design a framework that analyzes which information is leaked during privacy-preserving collab- N/2 [48,179,190] N −1 [70,80,153] N −2 [32] N −u [167,168] N −τ [17, 37, 41, 42, 55, 56, 71, 72, 95, 96, 100, 104, 111, 121, 122, 149, 156, 157, 160, 166, 181, 182, 186, 187] [5] N/2 [101,102] TH TH [16,19,20,34,59,60,62,68,79,83,84,105,114,137,140,146,171,177,183,188,192] orative tree-based model induction, enabling us to systematize the literature on that aspect. Although several works acknowledge this leakage and even provide an analysis of their solution [32,55,70,75,118,167,168,179], they do not do so in a systematic way.…”