A critical can be a parameter used in general public essential cryptography and can be represented by alphanumerical people or a fingerprint. PGP make use of a set of keys (general public and private) in addition to a fingerprint which identifies them. SSH keys also behave in a similar way. https://vanity-eth-address-genera64185.shoutmyblog.com/28868488/the-eth-vanity-address-generator-gpu-diaries