You can insert random text into bitcoin, which can include private info: https://www.reddit.com/r/btc/comments/49pp3n/eli5_how_to_embed_text_into_a_bitcoin_tran

You can insert random text into bitcoin, which can include private info: https://www.reddit.com/r/btc/comments/49pp3n/eli5_how_to_embed_text_into_a_bitcoin_transaction/ https://www.reddit.com/r/btc/comments/49pp3n/eli5_how_to_emb... There are also blockchain style social networks such as steem that create things that are like reddit: https://steem.io https://steem.io / https://steemit.com https://steemit.com . Again, freeform public text blobs that can have private info. If you create any censorship resistant publishing software, lets say to report on human rights violations in some sort of dictatorship, you also create something that can be used to violate the GDPR.