Abstract: Embodiments are disclosed for secure safety-critical system log. In an embodiment, a method comprises: obtaining data to be added to a log; creating an entry for the data; and adding the entry to a sequence of chained entries in the log, wherein: the sequence of chained entries includes a number of data entries and a number of sentinels interleaved with the number of data entries, wherein each data entry in the chain of entries is appended to an error-detecting code computed for the entry and a previously computed error-detecting code of a preceding data entry or an error-detecting root, and each sentinel in the chain of entries includes an error-detecting code computed for the sentinel and a previously computed error-detecting code of a preceding data entry or the error-detecting root, and each sentinel includes a previously computed and encrypted blockchain value of a preceding sentinel or a blockchain root value.