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csr.go
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csr.go
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/*-
* Copyright 2015 Square Inc.
* Copyright 2014 CoreOS
*
* Licensed 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 pkix
import (
"bytes"
"crypto"
"crypto/ecdsa"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/asn1"
"encoding/pem"
"errors"
"fmt"
"math/big"
"net"
"strings"
)
const (
csrPEMBlockType = "CERTIFICATE REQUEST"
)
var (
csrPkixName = pkix.Name{
Country: []string{},
Organization: []string{},
OrganizationalUnit: nil,
Locality: nil,
Province: nil,
StreetAddress: nil,
PostalCode: nil,
SerialNumber: "",
CommonName: "",
}
)
// ParseAndValidateIPs parses a comma-delimited list of IP addresses into an array of IP addresses
func ParseAndValidateIPs(ipList string) (res []net.IP, err error) {
// IP list can potentially be a blank string, ""
if len(ipList) > 0 {
ips := strings.Split(ipList, ",")
for _, ip := range ips {
parsedIP := net.ParseIP(ip)
if parsedIP == nil {
return nil, fmt.Errorf("Invalid IP address: %s", ip)
}
res = append(res, parsedIP)
}
}
return
}
// CreateCertificateSigningRequest sets up a request to create a csr file with the given parameters
func CreateCertificateSigningRequest(key *Key, organizationalUnit string, ipList []net.IP, domainList []string, organization string, country string, province string, locality string, commonName string) (*CertificateSigningRequest, error) {
csrPkixName.CommonName = commonName
if len(organizationalUnit) > 0 {
csrPkixName.OrganizationalUnit = []string{organizationalUnit}
}
if len(organization) > 0 {
csrPkixName.Organization = []string{organization}
}
if len(country) > 0 {
csrPkixName.Country = []string{country}
}
if len(province) > 0 {
csrPkixName.Province = []string{province}
}
if len(locality) > 0 {
csrPkixName.Locality = []string{locality}
}
csrTemplate := &x509.CertificateRequest{
Subject: csrPkixName,
IPAddresses: ipList,
DNSNames: domainList,
}
csrBytes, err := x509.CreateCertificateRequest(rand.Reader, csrTemplate, key.Private)
if err != nil {
return nil, err
}
return NewCertificateSigningRequestFromDER(csrBytes), nil
}
// CertificateSigningRequest is a wrapper around a x509 CertificateRequest and its DER-formatted bytes
type CertificateSigningRequest struct {
// derBytes is always set for valid Certificate
derBytes []byte
cr *x509.CertificateRequest
}
// NewCertificateSigningRequestFromDER inits CertificateSigningRequest from DER-format bytes
func NewCertificateSigningRequestFromDER(derBytes []byte) *CertificateSigningRequest {
return &CertificateSigningRequest{derBytes: derBytes}
}
// NewCertificateSigningRequestFromPEM inits CertificateSigningRequest from PEM-format bytes
// data should contain at most one certificate
func NewCertificateSigningRequestFromPEM(data []byte) (*CertificateSigningRequest, error) {
pemBlock, _ := pem.Decode(data)
if pemBlock == nil {
return nil, errors.New("cannot find the next PEM formatted block")
}
if pemBlock.Type != csrPEMBlockType || len(pemBlock.Headers) != 0 {
return nil, errors.New("unmatched type or headers")
}
return &CertificateSigningRequest{derBytes: pemBlock.Bytes}, nil
}
// build cr field if needed
func (c *CertificateSigningRequest) buildPKCS10CertificateSigningRequest() error {
if c.cr != nil {
return nil
}
var err error
c.cr, err = x509.ParseCertificateRequest(c.derBytes)
if err != nil {
return err
}
return nil
}
// GetRawCertificateSigningRequest returns a copy of this certificate request as an x509.CertificateRequest.
func (c *CertificateSigningRequest) GetRawCertificateSigningRequest() (*x509.CertificateRequest, error) {
if err := c.buildPKCS10CertificateSigningRequest(); err != nil {
return nil, err
}
return c.cr, nil
}
// CheckSignature verifies that the signature is a valid signature
// using the public key in CertificateSigningRequest.
func (c *CertificateSigningRequest) CheckSignature() error {
if err := c.buildPKCS10CertificateSigningRequest(); err != nil {
return err
}
return checkSignature(c.cr, c.cr.SignatureAlgorithm, c.cr.RawTBSCertificateRequest, c.cr.Signature)
}
// checkSignature verifies a signature made by the key on a CSR, such
// as on the CSR itself.
func checkSignature(csr *x509.CertificateRequest, algo x509.SignatureAlgorithm, signed, signature []byte) error {
var hashType crypto.Hash
switch algo {
case x509.SHA1WithRSA, x509.ECDSAWithSHA1:
hashType = crypto.SHA1
case x509.SHA256WithRSA, x509.ECDSAWithSHA256:
hashType = crypto.SHA256
case x509.SHA384WithRSA, x509.ECDSAWithSHA384:
hashType = crypto.SHA384
case x509.SHA512WithRSA, x509.ECDSAWithSHA512:
hashType = crypto.SHA512
default:
return x509.ErrUnsupportedAlgorithm
}
if !hashType.Available() {
return x509.ErrUnsupportedAlgorithm
}
h := hashType.New()
h.Write(signed)
digest := h.Sum(nil)
switch pub := csr.PublicKey.(type) {
case *rsa.PublicKey:
return rsa.VerifyPKCS1v15(pub, hashType, digest, signature)
case *ecdsa.PublicKey:
ecdsaSig := new(struct{ R, S *big.Int })
if _, err := asn1.Unmarshal(signature, ecdsaSig); err != nil {
return err
}
if ecdsaSig.R.Sign() <= 0 || ecdsaSig.S.Sign() <= 0 {
return errors.New("x509: ECDSA signature contained zero or negative values")
}
if !ecdsa.Verify(pub, digest, ecdsaSig.R, ecdsaSig.S) {
return errors.New("x509: ECDSA verification failure")
}
return nil
}
return x509.ErrUnsupportedAlgorithm
}
// Export returns PEM-format bytes
func (c *CertificateSigningRequest) Export() ([]byte, error) {
pemBlock := &pem.Block{
Type: csrPEMBlockType,
Headers: nil,
Bytes: c.derBytes,
}
buf := new(bytes.Buffer)
if err := pem.Encode(buf, pemBlock); err != nil {
return nil, err
}
return buf.Bytes(), nil
}