Add util/pki for creating and signing certificates (#1555)

This commit is contained in:
Jake Sanders 2020-04-21 15:03:33 +01:00 committed by GitHub
parent 211fd9b9a3
commit 05d2b34e10
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 339 additions and 0 deletions

85
util/pki/certoptions.go Normal file
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package pki
import (
"crypto/ed25519"
"crypto/x509"
"crypto/x509/pkix"
"math/big"
"net"
"time"
)
// CertOptions are passed to cert options
type CertOptions struct {
IsCA bool
Subject pkix.Name
DNSNames []string
IPAddresses []net.IP
SerialNumber *big.Int
NotBefore time.Time
NotAfter time.Time
Parent *x509.Certificate
Pub ed25519.PublicKey
Priv ed25519.PrivateKey
}
// CertOption sets CertOptions
type CertOption func(c *CertOptions)
// Subject sets the Subject field
func Subject(subject pkix.Name) CertOption {
return func(c *CertOptions) {
c.Subject = subject
}
}
// IsCA states the cert is a CA
func IsCA() CertOption {
return func(c *CertOptions) {
c.IsCA = true
}
}
// DNSNames is a list of hosts to sign in to the certificate
func DNSNames(names ...string) CertOption {
return func(c *CertOptions) {
c.DNSNames = names
}
}
// IPAddresses is a list of IPs to sign in to the certificate
func IPAddresses(ips ...net.IP) CertOption {
return func(c *CertOptions) {
c.IPAddresses = ips
}
}
// KeyPair is the key pair to sign the certificate with
func KeyPair(pub ed25519.PublicKey, priv ed25519.PrivateKey) CertOption {
return func(c *CertOptions) {
c.Pub = pub
c.Priv = priv
}
}
// SerialNumber is the Certificate Serial number
func SerialNumber(serial *big.Int) CertOption {
return func(c *CertOptions) {
c.SerialNumber = serial
}
}
// NotBefore is the time the certificate is not valid before
func NotBefore(time time.Time) CertOption {
return func(c *CertOptions) {
c.NotBefore = time
}
}
// NotAfter is the time the certificate is not valid after
func NotAfter(time time.Time) CertOption {
return func(c *CertOptions) {
c.NotAfter = time
}
}

164
util/pki/pki.go Normal file
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// Package pki provides PKI all the PKI functions necessary to run micro over an untrusted network
// including a CA
package pki
import (
"bytes"
"crypto/ed25519"
"crypto/rand"
"crypto/x509"
"encoding/pem"
"github.com/pkg/errors"
)
// GenerateKey returns an ed25519 key
func GenerateKey() (ed25519.PublicKey, ed25519.PrivateKey, error) {
return ed25519.GenerateKey(rand.Reader)
}
// CA generates a self signed CA and returns cert, key in PEM format
func CA(opts ...CertOption) ([]byte, []byte, error) {
opts = append(opts, IsCA())
options := CertOptions{}
for _, o := range opts {
o(&options)
}
template := &x509.Certificate{
SignatureAlgorithm: x509.PureEd25519,
Subject: options.Subject,
DNSNames: options.DNSNames,
IPAddresses: options.IPAddresses,
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
NotBefore: options.NotBefore,
NotAfter: options.NotAfter,
SerialNumber: options.SerialNumber,
BasicConstraintsValid: true,
}
if options.IsCA {
template.IsCA = true
template.KeyUsage |= x509.KeyUsageCertSign
}
x509Cert, err := x509.CreateCertificate(rand.Reader, template, template, options.Pub, options.Priv)
if err != nil {
return nil, nil, err
}
cert, key := &bytes.Buffer{}, &bytes.Buffer{}
if err := pem.Encode(cert, &pem.Block{Type: "CERTIFICATE", Bytes: x509Cert}); err != nil {
return nil, nil, err
}
x509Key, err := x509.MarshalPKCS8PrivateKey(options.Priv)
if err != nil {
return nil, nil, err
}
if err := pem.Encode(key, &pem.Block{Type: "PRIVATE KEY", Bytes: x509Key}); err != nil {
return nil, nil, err
}
return cert.Bytes(), key.Bytes(), nil
}
// CSR generates a certificate request in PEM format
func CSR(opts ...CertOption) ([]byte, error) {
options := CertOptions{}
for _, o := range opts {
o(&options)
}
csrTemplate := &x509.CertificateRequest{
Subject: options.Subject,
SignatureAlgorithm: x509.PureEd25519,
DNSNames: options.DNSNames,
IPAddresses: options.IPAddresses,
}
out := &bytes.Buffer{}
csr, err := x509.CreateCertificateRequest(rand.Reader, csrTemplate, options.Priv)
if err != nil {
return nil, err
}
if err := pem.Encode(out, &pem.Block{Type: "CERTIFICATE REQUEST", Bytes: csr}); err != nil {
return nil, err
}
return out.Bytes(), nil
}
// Sign decodes a CSR and signs it with the CA
func Sign(CACrt, CAKey, CSR []byte, opts ...CertOption) ([]byte, error) {
options := CertOptions{}
for _, o := range opts {
o(&options)
}
asn1CACrt, err := decodePEM(CACrt)
if err != nil {
return nil, errors.Wrap(err, "failed to decode CA Crt PEM")
}
if len(asn1CACrt) != 1 {
return nil, errors.Errorf("expected 1 CA Crt, got %d", len(asn1CACrt))
}
caCrt, err := x509.ParseCertificate(asn1CACrt[0].Bytes)
if err != nil {
return nil, errors.Wrap(err, "ca is not a valid certificate")
}
asn1CAKey, err := decodePEM(CAKey)
if err != nil {
return nil, errors.Wrap(err, "failed to decode CA Key PEM")
}
if len(asn1CAKey) != 1 {
return nil, errors.Errorf("expected 1 CA Key, got %d", len(asn1CACrt))
}
caKey, err := x509.ParsePKCS8PrivateKey(asn1CAKey[0].Bytes)
if err != nil {
return nil, errors.Wrap(err, "ca key is not a valid private key")
}
asn1CSR, err := decodePEM(CSR)
if err != nil {
return nil, errors.Wrap(err, "failed to decode CSR PEM")
}
if len(asn1CSR) != 1 {
return nil, errors.Errorf("expected 1 CSR, got %d", len(asn1CSR))
}
csr, err := x509.ParseCertificateRequest(asn1CSR[0].Bytes)
if err != nil {
return nil, errors.Wrap(err, "csr is invalid")
}
template := &x509.Certificate{
SignatureAlgorithm: x509.PureEd25519,
Subject: csr.Subject,
DNSNames: csr.DNSNames,
IPAddresses: csr.IPAddresses,
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
NotBefore: options.NotBefore,
NotAfter: options.NotAfter,
SerialNumber: options.SerialNumber,
BasicConstraintsValid: true,
}
x509Cert, err := x509.CreateCertificate(rand.Reader, template, caCrt, caCrt.PublicKey, caKey)
if err != nil {
return nil, errors.Wrap(err, "Couldn't sign certificate")
}
out := &bytes.Buffer{}
if err := pem.Encode(out, &pem.Block{Type: "CERTIFICATE", Bytes: x509Cert}); err != nil {
return nil, errors.Wrap(err, "couldn't encode cert")
}
return out.Bytes(), nil
}
func decodePEM(PEM []byte) ([]*pem.Block, error) {
var blocks []*pem.Block
var asn1 *pem.Block
var rest []byte
for {
asn1, rest = pem.Decode(PEM)
if asn1 == nil {
return nil, errors.New("PEM is not valid")
}
blocks = append(blocks, asn1)
if len(rest) == 0 {
break
}
}
return blocks, nil
}

90
util/pki/pki_test.go Normal file
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package pki
import (
"crypto/ed25519"
"crypto/rand"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"math/big"
"net"
"testing"
"time"
"github.com/stretchr/testify/assert"
)
func TestPrivateKey(t *testing.T) {
_, _, err := GenerateKey()
assert.NoError(t, err)
}
func TestCA(t *testing.T) {
pub, priv, err := GenerateKey()
assert.NoError(t, err)
serialNumberMax := new(big.Int).Lsh(big.NewInt(1), 128)
serialNumber, err := rand.Int(rand.Reader, serialNumberMax)
assert.NoError(t, err, "Couldn't generate serial")
cert, key, err := CA(
KeyPair(pub, priv),
Subject(pkix.Name{
Organization: []string{"test"},
}),
DNSNames("localhost"),
IPAddresses(net.ParseIP("127.0.0.1")),
SerialNumber(serialNumber),
NotBefore(time.Now().Add(time.Minute*-1)),
NotAfter(time.Now().Add(time.Minute)),
)
assert.NoError(t, err, "Couldn't sign CA")
asn1Key, _ := pem.Decode(key)
assert.NotNil(t, asn1Key, "Couldn't decode key")
assert.Equal(t, "PRIVATE KEY", asn1Key.Type)
decodedKey, err := x509.ParsePKCS8PrivateKey(asn1Key.Bytes)
assert.NoError(t, err, "Couldn't decode ASN1 Key")
assert.Equal(t, priv, decodedKey.(ed25519.PrivateKey))
pool := x509.NewCertPool()
assert.True(t, pool.AppendCertsFromPEM(cert), "Coudn't parse cert")
asn1Cert, _ := pem.Decode(cert)
assert.NotNil(t, asn1Cert, "Couldn't parse pem cert")
x509cert, err := x509.ParseCertificate(asn1Cert.Bytes)
assert.NoError(t, err, "Couldn't parse asn1 cert")
chains, err := x509cert.Verify(x509.VerifyOptions{
Roots: pool,
})
assert.NoError(t, err, "Cert didn't verify")
assert.Len(t, chains, 1, "CA should have 1 cert in chain")
}
func TestCSR(t *testing.T) {
pub, priv, err := GenerateKey()
assert.NoError(t, err)
csr, err := CSR(
Subject(
pkix.Name{
CommonName: "testnode",
Organization: []string{"microtest"},
OrganizationalUnit: []string{"super-testers"},
},
),
DNSNames("localhost"),
IPAddresses(net.ParseIP("127.0.0.1")),
KeyPair(pub, priv),
)
assert.NoError(t, err, "CSR couldn't be encoded")
asn1csr, _ := pem.Decode(csr)
assert.NotNil(t, asn1csr)
decodedcsr, err := x509.ParseCertificateRequest(asn1csr.Bytes)
assert.NoError(t, err)
expected := pkix.Name{
CommonName: "testnode",
Organization: []string{"microtest"},
OrganizationalUnit: []string{"super-testers"},
}
assert.Equal(t, decodedcsr.Subject.String(), expected.String())
}