PEMファイルの中身をダンプする

PEM形式のファイルの中身を確認するには、以下のようにすれば良い。

$ openssl x509 -in isrgrootx1.pem.txt -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
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                RSA Public-Key: (4096 bit)
                Modulus:
                    00:ad:e8:24:73:f4:14:37:f3:9b:9e:2b:57:28:1c:
                    87:be:dc:b7:df:38:90:8c:6e:3c:e6:57:a0:78:f7:
                    75:c2:a2:fe:f5:6a:6e:f6:00:4f:28:db:de:68:86:
                    6c:44:93:b6:b1:63:fd:14:12:6b:bf:1f:d2:ea:31:
(snip)