[isp]

    $ echo -n $'It\'s not too difficult. All you need is to generate many variations of potential words and check whether the sha256 hash matches the wanted leading characters. For example, check this text.' | sha256sum
    182a7c9d2e99162688aaaf3f97638edd7d06f8d295e456c7bb1f16abf3a8f70c  -

[wppick]

Isn't this kind of the same thing that crypto miners do?

[acchow]

Yes except Bitcoin does double SHA (a second round of SHA on the first result)