Ruby openssl生成証明書

require 'openssl'

key = OpenSSL::PKey::RSA.new(1024)
digest = OpenSSL::Digest::SHA1.new()

issu = sub = OpenSSL::X509::Name.new()
sub.add_entry('O', 'Organization')
sub.add_entry('OU', 'Project Implementation')
sub.add_entry('CN', 'Ruby OpenSSL')

cer = OpenSSL::X509::Certificate.new()
cer.not_before = Time.at(0)
cer.not_after = Time.at(0)
cer.public_key = key  # <=         
cer.serial = 1
cer.issuer = issu
cer.subject = sub

cer.sign(key, digest) # <=             
print cer.to_text
#  :      (Certificate.crt)
File.open("Certificate","w")<<cer