Class: OpenSSL::X509::Certificate
Relationships & Source Files | |
Inherits: | Object |
Defined in: | ext/openssl/ossl_x509cert.c, ext/openssl/lib/openssl/x509.rb |
Overview
Implementation of an X.509 certificate as specified in RFC 5280. Provides access to a certificate's attributes and allows certificates to be read from a string, but also supports the creation of new certificates from scratch.
Reading a certificate from a file
Certificate
is capable of handling DER-encoded certificates and certificates encoded in OpenSSL's PEM format.
raw = File.read "cert.cer" # DER- or PEM-encoded
certificate = OpenSSL::X509::Certificate.new raw
Saving a certificate to a file
A certificate may be encoded in DER format
cert = ...
File.open("cert.cer", "wb") { |f| f.print cert.to_der }
or in PEM format
cert = ...
File.open("cert.pem", "wb") { |f| f.print cert.to_pem }
X.509 certificates are associated with a private/public key pair, typically a RSA, DSA or ECC key (see also ::OpenSSL::PKey::RSA, ::OpenSSL::PKey::DSA and ::OpenSSL::PKey::EC), the public key itself is stored within the certificate and can be accessed in form of an ::OpenSSL::PKey. Certificates are typically used to be able to associate some form of identity with a key pair, for example web servers serving pages over HTTPs use certificates to authenticate themselves to the user.
The public key infrastructure (PKI) model relies on trusted certificate authorities (“root CAs”) that issue these certificates, so that end users need to base their trust just on a selected few authorities that themselves again vouch for subordinate CAs issuing their certificates to end users.
The ::OpenSSL::X509 module provides the tools to set up an independent PKI, similar to scenarios where the 'openssl' command line tool is used for issuing certificates in a private PKI.
Creating a root CA certificate and an end-entity certificate
First, we need to create a “self-signed” root certificate. To do so, we need to generate a key first. Please note that the choice of “1” as a serial number is considered a security flaw for real certificates. Secure choices are integers in the two-digit byte range and ideally not sequential but secure random numbers, steps omitted here to keep the example concise.
root_key = OpenSSL::PKey::RSA.new 2048 # the CA's public/private key
root_ca = OpenSSL::X509::Certificate.new
root_ca.version = 2 # cf. RFC 5280 - to make it a "v3" certificate
root_ca.serial = 1
root_ca.subject = OpenSSL::X509::Name.parse "/DC=org/DC=ruby-lang/CN=Ruby CA"
root_ca.issuer = root_ca.subject # root CA's are "self-signed"
root_ca.public_key = root_key.public_key
root_ca.not_before = Time.now
root_ca.not_after = root_ca.not_before + 2 * 365 * 24 * 60 * 60 # 2 years validity
ef = OpenSSL::X509::ExtensionFactory.new
ef.subject_certificate = root_ca
ef.issuer_certificate = root_ca
root_ca.add_extension(ef.create_extension("basicConstraints","CA:TRUE",true))
root_ca.add_extension(ef.create_extension("keyUsage","keyCertSign, cRLSign", true))
root_ca.add_extension(ef.create_extension("subjectKeyIdentifier","hash",false))
root_ca.add_extension(ef.create_extension("authorityKeyIdentifier","keyid:always",false))
root_ca.sign(root_key, OpenSSL::Digest::SHA256.new)
The next step is to create the end-entity certificate using the root CA certificate.
key = OpenSSL::PKey::RSA.new 2048
cert = OpenSSL::X509::Certificate.new
cert.version = 2
cert.serial = 2
cert.subject = OpenSSL::X509::Name.parse "/DC=org/DC=ruby-lang/CN=Ruby certificate"
cert.issuer = root_ca.subject # root CA is the issuer
cert.public_key = key.public_key
cert.not_before = Time.now
cert.not_after = cert.not_before + 1 * 365 * 24 * 60 * 60 # 1 years validity
ef = OpenSSL::X509::ExtensionFactory.new
ef.subject_certificate = cert
ef.issuer_certificate = root_ca
cert.add_extension(ef.create_extension("keyUsage","digitalSignature", true))
cert.add_extension(ef.create_extension("subjectKeyIdentifier","hash",false))
cert.sign(root_key, OpenSSL::Digest::SHA256.new)
Class Method Summary
- .new ⇒ cert constructor
Instance Attribute Summary
- #extensions ⇒ Array rw
- #extensions=([ext...]=> [ext...]) rw
- #issuer ⇒ name rw
- #issuer=(name) ⇒ name rw
- #not_after ⇒ Time rw
- #not_after=(time) ⇒ Time rw
- #not_before ⇒ Time rw
- #not_before=(time) ⇒ Time rw
- #public_key ⇒ key rw
- #public_key=(key) rw
- #serial ⇒ Integer rw
- #serial=(integer) ⇒ Integer rw
- #subject ⇒ name rw
- #subject=(name) ⇒ name rw
- #version ⇒ Integer rw
- #version=(integer) ⇒ Integer rw
Instance Method Summary
- #add_extension(extension) ⇒ extension
-
#check_private_key(key)
Checks if 'key' is PRIV key for this cert.
- #inspect
- #pretty_print(q)
- #sign(key, digest) ⇒ self
- #signature_algorithm ⇒ String
- #to_der ⇒ String
-
#to_pem ⇒ String
Alias for #to_s.
- #to_s ⇒ String (also: #to_pem)
- #to_text ⇒ String
-
#verify(key) ⇒ Boolean
Checks that cert signature is made with PRIVversion of this PUBLIC 'key'.
Constructor Details
.new ⇒ cert
.new(string) ⇒ cert
cert
.new(string) ⇒ cert
Instance Attribute Details
#extensions ⇒ Array
(rw)
#extensions=([ext...]=> [ext...]) (rw)
#issuer ⇒ name
(rw)
#issuer=(name) ⇒ name
(rw)
#not_after ⇒ Time
(rw)
#not_after=(time) ⇒ Time
(rw)
#not_before ⇒ Time
(rw)
#not_before=(time) ⇒ Time
(rw)
#public_key ⇒ key
(rw)
#public_key=(key) (rw)
#serial ⇒ Integer (rw)
#serial=(integer) ⇒ Integer (rw)
#subject ⇒ name
(rw)
#subject=(name) ⇒ name
(rw)
#version ⇒ Integer (rw)
#version=(integer) ⇒ Integer (rw)
Instance Method Details
#add_extension(extension) ⇒ extension
#check_private_key(key)
Checks if 'key' is PRIV key for this cert
#inspect
#pretty_print(q)
[ GitHub ]# File 'ext/openssl/lib/openssl/x509.rb', line 164
def pretty_print(q) q.object_group(self) { q.breakable q.text 'subject='; q.pp self.subject; q.text ','; q.breakable q.text 'issuer='; q.pp self.issuer; q.text ','; q.breakable q.text 'serial='; q.pp self.serial; q.text ','; q.breakable q.text 'not_before='; q.pp self.not_before; q.text ','; q.breakable q.text 'not_after='; q.pp self.not_after } end
#sign(key, digest) ⇒ self
#signature_algorithm ⇒ String
#to_der ⇒ String
#to_s ⇒ String
#to_pem ⇒ String
String
#to_pem ⇒ String
Alias for #to_s.
#to_s ⇒ String
Also known as: #to_pem
#to_text ⇒ String
#verify(key) ⇒ Boolean
Checks that cert signature is made with PRIVversion of this PUBLIC 'key'