“…Anonymization (31 papers) [34]- [64] Obfuscation (15 papers) [64]- [78] Multi-tier ML (5 papers) [79]- [83] Decentralized ML (10 papers) [78], [84]- [92] Cryptography (154 papers) [48], [51], [59], [62], [63], [76], [83], [85], [86], [92]- [236] Dataflow (51 papers) [61], [82], [83], [89], [101], [165], [216], [221], [223], [237]- [278] Data summarization (6 papers) [279]- [284] Personal data stores (2 papers) [285], [286] ensure privacy (a) blockchain which is used for verifiability and accountability of data collection, storage and access in IoT environments [31]; and (b) privacybased programming languages, which require information flows and privileges to be declared beforehand, so all the data elements are attached to respective policies [32]. 7) Data summarization: it is a process of creating a concise, yet informative, version of data to preserve the privacy of the original data.…”