cert.go

/*
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.
*/

package utils

import (
	"crypto/ecdsa"
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/asn1"
	"encoding/pem"
	"errors"
	"math/big"
	"net"
	"time"
)

var (
	// TCertEncTCertIndex oid for TCertIndex
	TCertEncTCertIndex = asn1.ObjectIdentifier{1, 2, 3, 4, 5, 6, 7}
)

// DERToX509Certificate converts der to x509
func DERToX509Certificate(asn1Data []byte) (*x509.Certificate, error) {
	return x509.ParseCertificate(asn1Data)
}

// PEMtoCertificate converts pem to x509
func PEMtoCertificate(raw []byte) (*x509.Certificate, error) {
	block, _ := pem.Decode(raw)
	if block == nil {
		return nil, errors.New("No PEM block available")
	}

	if block.Type != "CERTIFICATE" || len(block.Headers) != 0 {
		return nil, errors.New("Not a valid CERTIFICATE PEM block")
	}

	cert, err := x509.ParseCertificate(block.Bytes)
	if err != nil {
		return nil, err
	}

	return cert, nil
}

// PEMtoDER converts pem to der
func PEMtoDER(raw []byte) ([]byte, error) {
	block, _ := pem.Decode(raw)
	if block == nil {
		return nil, errors.New("No PEM block available")
	}

	if block.Type != "CERTIFICATE" || len(block.Headers) != 0 {
		return nil, errors.New("Not a valid CERTIFICATE PEM block")
	}

	return block.Bytes, nil
}

// PEMtoCertificateAndDER converts pem to x509 and der
func PEMtoCertificateAndDER(raw []byte) (*x509.Certificate, []byte, error) {
	block, _ := pem.Decode(raw)
	if block == nil {
		return nil, nil, errors.New("No PEM block available")
	}

	if block.Type != "CERTIFICATE" || len(block.Headers) != 0 {
		return nil, nil, errors.New("Not a valid CERTIFICATE PEM block")
	}

	cert, err := x509.ParseCertificate(block.Bytes)
	if err != nil {
		return nil, nil, err
	}

	return cert, block.Bytes, nil
}

// DERCertToPEM converts der to pem
func DERCertToPEM(der []byte) []byte {
	return pem.EncodeToMemory(
		&pem.Block{
			Type:  "CERTIFICATE",
			Bytes: der,
		},
	)
}

// GetCriticalExtension returns a requested critical extension. It also remove it from the list
// of unhandled critical extensions
func GetCriticalExtension(cert *x509.Certificate, oid asn1.ObjectIdentifier) ([]byte, error) {
	for i, ext := range cert.UnhandledCriticalExtensions {
		if IntArrayEquals(ext, oid) {
			cert.UnhandledCriticalExtensions = append(cert.UnhandledCriticalExtensions[:i], cert.UnhandledCriticalExtensions[i+1:]...)

			break
		}
	}

	for _, ext := range cert.Extensions {
		if IntArrayEquals(ext.Id, oid) {
			return ext.Value, nil
		}
	}

	return nil, errors.New("Failed retrieving extension.")
}

// NewSelfSignedCert create a self signed certificate
func NewSelfSignedCert() ([]byte, interface{}, error) {
	privKey, err := NewECDSAKey()
	if err != nil {
		return nil, nil, err
	}

	testExtKeyUsage := []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth}
	testUnknownExtKeyUsage := []asn1.ObjectIdentifier{[]int{1, 2, 3}, []int{2, 59, 1}}
	extraExtensionData := []byte("extra extension")
	commonName := "test.example.com"
	template := x509.Certificate{
		SerialNumber: big.NewInt(1),
		Subject: pkix.Name{
			CommonName:   commonName,
			Organization: []string{"Σ Acme Co"},
			Country:      []string{"US"},
			ExtraNames: []pkix.AttributeTypeAndValue{
				{
					Type:  []int{2, 5, 4, 42},
					Value: "Gopher",
				},
				// This should override the Country, above.
				{
					Type:  []int{2, 5, 4, 6},
					Value: "NL",
				},
			},
		},
		NotBefore: time.Unix(1000, 0),
		NotAfter:  time.Unix(100000, 0),

		SignatureAlgorithm: x509.ECDSAWithSHA384,

		SubjectKeyId: []byte{1, 2, 3, 4},
		KeyUsage:     x509.KeyUsageCertSign,

		ExtKeyUsage:        testExtKeyUsage,
		UnknownExtKeyUsage: testUnknownExtKeyUsage,

		BasicConstraintsValid: true,
		IsCA: true,

		OCSPServer:            []string{"http://ocsp.example.com"},
		IssuingCertificateURL: []string{"http://crt.example.com/ca1.crt"},

		DNSNames:       []string{"test.example.com"},
		EmailAddresses: []string{"gopher@golang.org"},
		IPAddresses:    []net.IP{net.IPv4(127, 0, 0, 1).To4(), net.ParseIP("2001:4860:0:2001::68")},

		PolicyIdentifiers:   []asn1.ObjectIdentifier{[]int{1, 2, 3}},
		PermittedDNSDomains: []string{".example.com", "example.com"},

		CRLDistributionPoints: []string{"http://crl1.example.com/ca1.crl", "http://crl2.example.com/ca1.crl"},

		ExtraExtensions: []pkix.Extension{
			{
				Id:    []int{1, 2, 3, 4},
				Value: extraExtensionData,
			},
		},
	}

	cert, err := x509.CreateCertificate(rand.Reader, &template, &template, &privKey.PublicKey, privKey)
	if err != nil {
		return nil, nil, err
	}

	return cert, privKey, nil
}

func CheckCertPKAgainstSK(x509Cert *x509.Certificate, privateKey interface{}) error {
	switch pub := x509Cert.PublicKey.(type) {
	case *rsa.PublicKey:
		priv, ok := privateKey.(*rsa.PrivateKey)
		if !ok {
			return errors.New("Private key type does not match public key type")
		}
		if pub.N.Cmp(priv.N) != 0 {
			return errors.New("Private key does not match public key")
		}
	case *ecdsa.PublicKey:
		priv, ok := privateKey.(*ecdsa.PrivateKey)
		if !ok {
			return errors.New("Private key type does not match public key type")

		}
		if pub.X.Cmp(priv.X) != 0 || pub.Y.Cmp(priv.Y) != 0 {
			return errors.New("Private key does not match public key")
		}
	default:
		return errors.New("Unknown public key algorithm")
	}

	return nil
}

func CheckCertAgainRoot(x509Cert *x509.Certificate, certPool *x509.CertPool) ([][]*x509.Certificate, error) {
	opts := x509.VerifyOptions{
		// TODO		DNSName: "test.example.com",
		Roots: certPool,
	}

	return x509Cert.Verify(opts)
}

func CheckCertAgainstSKAndRoot(x509Cert *x509.Certificate, privateKey interface{}, certPool *x509.CertPool) error {
	if err := CheckCertPKAgainstSK(x509Cert, privateKey); err != nil {
		return err
	}

	if _, err := CheckCertAgainRoot(x509Cert, certPool); err != nil {
		return err
	}

	return nil
}