Postgres 14

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CREATE EXTENSION

with invar as (
  select '-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----' as cert
)
select rtrim(          -- deal with trailing = signs
         encode(                -- base64 of sha256 hash
           digest(              -- create sha256 hash
             decode(            -- get cert bytes from base64
               regexp_replace(  -- remove BEGIN and END lines
                 cert, '(-.*?-)', '', 'g'
               ),
               'base64'
             ),
             'sha256'
           ),
           'base64'
         ),
         '='
       )
  from invar;

rtrim
Zv2OGTzr7Nq7L2ijjjIY8ZSUIi9fVvxFtjmO7gYU0CY

SELECT 1