ASN1.decode(der)
DER表現の文字列を解析し、OpenSSL::ASN1::ASN1Data(のサブクラス)のインスタンスを返す。
ruby -e ' require "openssl" require "pp" pem = File.read(ARGV[0]) cert = OpenSSL::X509::Certificate.new(pem) pp OpenSSL::ASN1.decode(cert.to_der) ' mycert.pem #<OpenSSL::ASN1::Sequence:0x814e9fc @tag=16, @tag_class=:UNIVERSAL, @tagging=nil, @value= [#<OpenSSL::ASN1::Sequence:0x814ead8 @tag=16, @tag_class=:UNIVERSAL, @tagging=nil, @value= [#<OpenSSL::ASN1::ASN1Data:0x814f690 @tag=0, @tag_class=:CONTEXT_SPECIFIC, @value= [#<OpenSSL::ASN1::Integer:0x814f6a4 @tag=2, @tag_class=:UNIVERSAL, @tagging=nil, @value=2>]>, ...