blob: 39a6751f70ab8ad0fa8797bdf67e71c0908e6e51 [file] [log] [blame]
Zack Williamse940c7a2019-08-21 14:25:39 -07001/*
2Copyright 2016 The Kubernetes Authors.
3
4Licensed under the Apache License, Version 2.0 (the "License");
5you may not use this file except in compliance with the License.
6You may obtain a copy of the License at
7
8 http://www.apache.org/licenses/LICENSE-2.0
9
10Unless required by applicable law or agreed to in writing, software
11distributed under the License is distributed on an "AS IS" BASIS,
12WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13See the License for the specific language governing permissions and
14limitations under the License.
15*/
16
17package cert
18
19import (
20 cryptorand "crypto/rand"
21 "crypto/rsa"
22 "crypto/x509"
23 "crypto/x509/pkix"
24 "encoding/pem"
25 "net"
26)
27
28// MakeCSR generates a PEM-encoded CSR using the supplied private key, subject, and SANs.
29// All key types that are implemented via crypto.Signer are supported (This includes *rsa.PrivateKey and *ecdsa.PrivateKey.)
30func MakeCSR(privateKey interface{}, subject *pkix.Name, dnsSANs []string, ipSANs []net.IP) (csr []byte, err error) {
31 template := &x509.CertificateRequest{
32 Subject: *subject,
33 DNSNames: dnsSANs,
34 IPAddresses: ipSANs,
35 }
36
37 return MakeCSRFromTemplate(privateKey, template)
38}
39
40// MakeCSRFromTemplate generates a PEM-encoded CSR using the supplied private
41// key and certificate request as a template. All key types that are
42// implemented via crypto.Signer are supported (This includes *rsa.PrivateKey
43// and *ecdsa.PrivateKey.)
44func MakeCSRFromTemplate(privateKey interface{}, template *x509.CertificateRequest) ([]byte, error) {
45 t := *template
46 t.SignatureAlgorithm = sigType(privateKey)
47
48 csrDER, err := x509.CreateCertificateRequest(cryptorand.Reader, &t, privateKey)
49 if err != nil {
50 return nil, err
51 }
52
53 csrPemBlock := &pem.Block{
54 Type: CertificateRequestBlockType,
55 Bytes: csrDER,
56 }
57
58 return pem.EncodeToMemory(csrPemBlock), nil
59}
60
61func sigType(privateKey interface{}) x509.SignatureAlgorithm {
62 // Customize the signature for RSA keys, depending on the key size
63 if privateKey, ok := privateKey.(*rsa.PrivateKey); ok {
64 keySize := privateKey.N.BitLen()
65 switch {
66 case keySize >= 4096:
67 return x509.SHA512WithRSA
68 case keySize >= 3072:
69 return x509.SHA384WithRSA
70 default:
71 return x509.SHA256WithRSA
72 }
73 }
74 return x509.UnknownSignatureAlgorithm
75}