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# frozen_string_literal: true
module SmimeHelper
INFINITE_EXPIRY = 1000.years
SHORT_EXPIRY = 30.minutes
def generate_root
issue(cn: 'RootCA', signed_by: nil, expires_in: INFINITE_EXPIRY, certificate_authority: true)
end
def generate_intermediate(signer_ca:)
issue(cn: 'IntermediateCA', signed_by: signer_ca, expires_in: INFINITE_EXPIRY, certificate_authority: true)
end
def generate_cert(signer_ca:, expires_in: SHORT_EXPIRY)
issue(signed_by: signer_ca, expires_in: expires_in, certificate_authority: false)
end
# returns a hash { key:, cert: } containing a generated key, cert pair
def issue(signed_by:, expires_in:, certificate_authority:, email_address: 'test@example.com', cn: nil)
key = OpenSSL::PKey::RSA.new(4096)
public_key = key.public_key
subject = if certificate_authority
OpenSSL::X509::Name.parse("/CN=#{cn}")
else
OpenSSL::X509::Name.parse("/CN=#{email_address}")
end
cert = OpenSSL::X509::Certificate.new
cert.subject = subject
cert.issuer = signed_by&.fetch(:cert, nil)&.subject || subject
cert.not_before = Time.now
cert.not_after = expires_in.from_now
cert.public_key = public_key
cert.serial = 0x0
cert.version = 2
extension_factory = OpenSSL::X509::ExtensionFactory.new
if certificate_authority
extension_factory.subject_certificate = cert
extension_factory.issuer_certificate = cert
cert.add_extension(extension_factory.create_extension('subjectKeyIdentifier', 'hash'))
cert.add_extension(extension_factory.create_extension('basicConstraints', 'CA:TRUE', true))
cert.add_extension(extension_factory.create_extension('keyUsage', 'cRLSign,keyCertSign', true))
else
cert.add_extension(extension_factory.create_extension('subjectAltName', "email:#{email_address}", false))
cert.add_extension(extension_factory.create_extension('basicConstraints', 'CA:FALSE', true))
cert.add_extension(extension_factory.create_extension('keyUsage', 'digitalSignature,keyEncipherment', true))
cert.add_extension(extension_factory.create_extension('extendedKeyUsage', 'clientAuth,emailProtection', false))
end
cert.sign(signed_by&.fetch(:key, nil) || key, OpenSSL::Digest.new('SHA256'))
{ key: key, cert: cert }
end
end
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