$ openssl x509 -in /usr/share/ca-certificates/mozilla/ISRG_Root_X1.crt -noout -text
Certificate:
Data:
Version: 3 (0x2)
Serial Number:
82:10:cf:b0:d2:40:e3:59:44:63:e0:bb:63:82:8b:00
Signature Algorithm: sha256WithRSAEncryption
Issuer: C=US, O=Internet Security Research Group, CN=ISRG Root X1
Validity
Not Before: Jun 4 11:04:38 2015 GMT
Not After : Jun 4 11:04:38 2035 GMT
Subject: C=US, O=Internet Security Research Group, CN=ISRG Root X1
おー!