$ pgpdump /usr/share/distribution-gpg-keys/centos/RPM-GPG-KEY-CentOS-9
Old: Public Key Packet(tag 6)(525 bytes)
        Ver 4 - new
        Public key creation time - Fri May  3 08:15:37 PDT 2019
        Pub alg - RSA Encrypt or Sign(pub 1)
        RSA n(4096 bits) - ...
        RSA e(17 bits) - ...
Old: User ID Packet(tag 13)(58 bytes)
        User ID - CentOS (CentOS Official Signing Key) <security@centos.org>
Old: Signature Packet(tag 2)(567 bytes)
        Ver 4 - new
        Sig type - Positive certification of a User ID and Public Key packet(0x13).
        Pub alg - RSA Encrypt or Sign(pub 1)
        Hash alg - SHA1(hash 2)
        Hashed Sub: signature creation time(sub 2)(4 bytes)
                Time - Fri May  3 08:15:37 PDT 2019
        Hashed Sub: key flags(sub 27)(1 bytes)
                Flag - This key may be used to certify other keys
                Flag - This key may be used to sign data
        Hashed Sub: preferred symmetric algorithms(sub 11)(5 bytes)
                Sym alg - AES with 256-bit key(sym 9)
                Sym alg - AES with 192-bit key(sym 8)
                Sym alg - AES with 128-bit key(sym 7)
                Sym alg - CAST5(sym 3)
                Sym alg - Triple-DES(sym 2)
        Hashed Sub: preferred hash algorithms(sub 21)(5 bytes)
                Hash alg - SHA256(hash 8)
                Hash alg - SHA1(hash 2)
                Hash alg - SHA384(hash 9)
                Hash alg - SHA512(hash 10)
                Hash alg - SHA224(hash 11)
        Hashed Sub: preferred compression algorithms(sub 22)(2 bytes)
                Comp alg - ZLIB <RFC1950>(comp 2)
                Comp alg - ZIP <RFC1951>(comp 1)
        Hashed Sub: features(sub 30)(1 bytes)
                Flag - Modification detection (packets 18 and 19)
        Hashed Sub: key server preferences(sub 23)(1 bytes)
                Flag - No-modify
        Sub: issuer key ID(sub 16)(8 bytes)
                Key ID - 0x05B555B38483C65D
        Hash left 2 bytes - 8c eb
        RSA m^d mod n(4095 bits) - ...
                -> PKCS-1