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generate.go
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generate.go
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package tlsutil
import (
"bytes"
"crypto"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
"crypto/sha256"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"math/big"
"net"
"strings"
"time"
"net/url"
)
const (
DefaultPrivateKeyType = "ec"
DefaultPrivateKeyBits = 256
DefaultIntermediateCertTTL = 24 * 365 * time.Hour
)
func pemEncode(value []byte, blockType string) (string, error) {
var buf bytes.Buffer
if err := pem.Encode(&buf, &pem.Block{Type: blockType, Bytes: value}); err != nil {
return "", fmt.Errorf("error encoding value %v: %s", blockType, err)
}
return buf.String(), nil
}
// ParseSigner parses a crypto.Signer from a PEM-encoded key. The private key
// is expected to be the first block in the PEM value.
func ParseSigner(pemValue string) (crypto.Signer, error) {
// The _ result below is not an error but the remaining PEM bytes.
block, _ := pem.Decode([]byte(pemValue))
if block == nil {
return nil, fmt.Errorf("no PEM-encoded data found")
}
switch block.Type {
case "EC PRIVATE KEY":
return x509.ParseECPrivateKey(block.Bytes)
case "RSA PRIVATE KEY":
return x509.ParsePKCS1PrivateKey(block.Bytes)
case "PRIVATE KEY":
signer, err := x509.ParsePKCS8PrivateKey(block.Bytes)
if err != nil {
return nil, err
}
pk, ok := signer.(crypto.Signer)
if !ok {
return nil, fmt.Errorf("private key is not a valid format")
}
return pk, nil
default:
return nil, fmt.Errorf("unknown PEM block type for signing key: %s", block.Type)
}
}
// GenerateSerialNumber returns random bigint generated with crypto/rand
func GenerateSerialNumber() (*big.Int, error) {
l := new(big.Int).Lsh(big.NewInt(1), 128)
s, err := rand.Int(rand.Reader, l)
if err != nil {
return nil, err
}
return s, nil
}
func generateECDSAKey(keyBits int) (crypto.Signer, string, error) {
var pk *ecdsa.PrivateKey
var curve elliptic.Curve
switch keyBits {
case 224:
curve = elliptic.P224()
case 256:
curve = elliptic.P256()
case 384:
curve = elliptic.P384()
case 521:
curve = elliptic.P521()
default:
return nil, "", fmt.Errorf("error generating ECDSA private key: unknown curve length %d", keyBits)
}
pk, err := ecdsa.GenerateKey(curve, rand.Reader)
if err != nil {
return nil, "", fmt.Errorf("error generating ECDSA private key: %s", err)
}
bs, err := x509.MarshalECPrivateKey(pk)
if err != nil {
return nil, "", fmt.Errorf("error marshaling ECDSA private key: %s", err)
}
pemBlock, err := pemEncode(bs, "EC PRIVATE KEY")
if err != nil {
return nil, "", err
}
return pk, pemBlock, nil
}
func generateRSAKey(keyBits int) (crypto.Signer, string, error) {
var pk *rsa.PrivateKey
pk, err := rsa.GenerateKey(rand.Reader, keyBits)
if err != nil {
return nil, "", fmt.Errorf("error generating RSA private key: %s", err)
}
bs := x509.MarshalPKCS1PrivateKey(pk)
pemBlock, err := pemEncode(bs, "RSA PRIVATE KEY")
if err != nil {
return nil, "", err
}
return pk, pemBlock, nil
}
// GeneratePrivateKey generates a new Private key
func GeneratePrivateKeyWithConfig(keyType string, keyBits int) (crypto.Signer, string, error) {
switch strings.ToLower(keyType) {
case "rsa":
return generateRSAKey(keyBits)
case "ec":
return generateECDSAKey(keyBits)
default:
return nil, "", fmt.Errorf("unknown private key type requested: %s", keyType)
}
}
func GeneratePrivateKey() (crypto.Signer, string, error) {
// TODO: find any calls to this func, replace with calls to GeneratePrivateKeyWithConfig()
// using prefs `private_key_type` and `private_key_bits`
return GeneratePrivateKeyWithConfig(DefaultPrivateKeyType, DefaultPrivateKeyBits)
}
type CAOpts struct {
Signer crypto.Signer
Serial *big.Int
ClusterID string
Days int
PermittedDNSDomains []string
Domain string
Name string
}
type CertOpts struct {
Signer crypto.Signer
CA string
Serial *big.Int
Name string
Days int
DNSNames []string
IPAddresses []net.IP
ExtKeyUsage []x509.ExtKeyUsage
IsCA bool
}
// GenerateCA generates a new CA for agent TLS (not to be confused with Connect TLS)
func GenerateCA(opts CAOpts) (string, string, error) {
signer := opts.Signer
var pk string
if signer == nil {
var err error
signer, pk, err = GeneratePrivateKey()
if err != nil {
return "", "", err
}
}
id, err := keyID(signer.Public())
if err != nil {
return "", "", err
}
sn := opts.Serial
if sn == nil {
var err error
sn, err = GenerateSerialNumber()
if err != nil {
return "", "", err
}
}
name := opts.Name
if name == "" {
name = fmt.Sprintf("Consul Agent CA %d", sn)
}
days := opts.Days
if opts.Days == 0 {
days = 365
}
var uris []*url.URL
// Create the CA cert
template := x509.Certificate{
SerialNumber: sn,
URIs: uris,
Subject: pkix.Name{
Organization: []string{"Bloomin' Labs, LLC"},
CommonName: name,
},
BasicConstraintsValid: true,
KeyUsage: x509.KeyUsageCertSign | x509.KeyUsageCRLSign | x509.KeyUsageDigitalSignature,
IsCA: true,
NotAfter: time.Now().AddDate(0, 0, days),
NotBefore: time.Now(),
AuthorityKeyId: id,
SubjectKeyId: id,
}
if len(opts.PermittedDNSDomains) > 0 {
template.PermittedDNSDomainsCritical = true
template.PermittedDNSDomains = opts.PermittedDNSDomains
}
bs, err := x509.CreateCertificate(
rand.Reader, &template, &template, signer.Public(), signer)
if err != nil {
return "", "", fmt.Errorf("error generating CA certificate: %s", err)
}
var buf bytes.Buffer
err = pem.Encode(&buf, &pem.Block{Type: "CERTIFICATE", Bytes: bs})
if err != nil {
return "", "", fmt.Errorf("error encoding private key: %s", err)
}
return buf.String(), pk, nil
}
// GenerateCert generates a new certificate for TLS
func GenerateCert(opts CertOpts) (string, string, error) {
parent, err := parseCert(opts.CA)
if err != nil {
return "", "", fmt.Errorf("failed to parse CA: %w", err)
}
signee, pk, err := GeneratePrivateKey()
if err != nil {
return "", "", fmt.Errorf("failed to generate private key: %w", err)
}
id, err := keyID(signee.Public())
if err != nil {
return "", "", fmt.Errorf("failed to get keyID from public key: %w", err)
}
sn := opts.Serial
if sn == nil {
var err error
sn, err = GenerateSerialNumber()
if err != nil {
return "", "", err
}
}
template := x509.Certificate{
SerialNumber: sn,
Subject: pkix.Name{CommonName: opts.Name},
BasicConstraintsValid: true,
KeyUsage: x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment,
ExtKeyUsage: opts.ExtKeyUsage,
IsCA: false,
NotAfter: time.Now().AddDate(0, 0, opts.Days),
NotBefore: time.Now(),
SubjectKeyId: id,
DNSNames: opts.DNSNames,
IPAddresses: opts.IPAddresses,
}
if opts.IsCA {
template.IsCA = true
template.KeyUsage = x509.KeyUsageCertSign | x509.KeyUsageCRLSign | x509.KeyUsageDigitalSignature
}
bs, err := x509.CreateCertificate(rand.Reader, &template, parent, signee.Public(), opts.Signer)
if err != nil {
return "", "", fmt.Errorf("failed to create certificate: %w", err)
}
var buf bytes.Buffer
err = pem.Encode(&buf, &pem.Block{Type: "CERTIFICATE", Bytes: bs})
if err != nil {
return "", "", fmt.Errorf("error encoding private key: %s", err)
}
return buf.String(), pk, nil
}
// KeyId returns a x509 KeyId from the given signing key.
func keyID(raw interface{}) ([]byte, error) {
switch raw.(type) {
case *ecdsa.PublicKey:
case *rsa.PublicKey:
default:
return nil, fmt.Errorf("invalid key type: %T", raw)
}
// This is not standard; RFC allows any unique identifier as long as they
// match in subject/authority chains but suggests specific hashing of DER
// bytes of public key including DER tags.
bs, err := x509.MarshalPKIXPublicKey(raw)
if err != nil {
return nil, err
}
// String formatted
kID := sha256.Sum256(bs)
return kID[:], nil
}
func parseCert(pemValue string) (*x509.Certificate, error) {
// The _ result below is not an error but the remaining PEM bytes.
block, _ := pem.Decode([]byte(pemValue))
if block == nil {
return nil, fmt.Errorf("no PEM-encoded data found")
}
if block.Type != "CERTIFICATE" {
return nil, fmt.Errorf("first PEM-block should be CERTIFICATE type")
}
return x509.ParseCertificate(block.Bytes)
}
func Verify(caString, certString, dns string) error {
roots := x509.NewCertPool()
ok := roots.AppendCertsFromPEM([]byte(caString))
if !ok {
return fmt.Errorf("failed to parse root certificate")
}
cert, err := parseCert(certString)
if err != nil {
return fmt.Errorf("failed to parse certificate")
}
opts := x509.VerifyOptions{
DNSName: fmt.Sprint(dns),
Roots: roots,
}
_, err = cert.Verify(opts)
return err
}