The founder of Wikileaks, Julian Assange, has given proof of life with the reading of the hash of the most recent block in the Bitcoin blockchain. He did this during an ask-me-anything (AMA) session via the popular discussion forum Reddit .
An AMA is a moment when users of the website can ask questions to important or known people. For example, Elon Musk had previously done an AMA.
The idea behind this way of proof of life is that each block in the Bitcoin blockchain can be identified with a unique set of letters and numbers ( hash ), of which it is impossible to gamble in advance. The reading of this unique series of letters and numbers proves that someone was alive at the time the block in question was produced. The idea is similar to making a photograph of the person in question that keeps a recent newspaper with the date visible upwards, as is sometimes the case with hostage-taking.
Assange indicates in the interview that the reading of the unique block hash is not optimal as proof of life. The reason he gives for this is that it is difficult for the average person to understand how the complicated technique works exactly behind Bitcoin and why a block can not be falsified. As a result, it is necessary to trust the experts in this area - which shifts the evidence from technical verification to trust in the experts.
The block that Assange read had the unique series 178374f687728789caa92ecb49b4d850dfc173a7c0351e6 and was number 447506 in the Bitcoin blockchain. The interview with Assange can be seen here, the part about proof of life starts at 01:53:00.