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crypto.go
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crypto.go
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// Copyright 2015 Matthew Holt
//
// 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 certmagic
import (
"context"
"crypto"
"crypto/ecdsa"
"crypto/ed25519"
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
"crypto/sha256"
"crypto/tls"
"crypto/x509"
"encoding/json"
"encoding/pem"
"errors"
"fmt"
"hash/fnv"
"io/fs"
"sort"
"strings"
"github.com/klauspost/cpuid/v2"
"go.uber.org/zap"
"golang.org/x/net/idna"
)
// PEMEncodePrivateKey marshals a private key into a PEM-encoded block.
// The private key must be one of *ecdsa.PrivateKey, *rsa.PrivateKey, or
// *ed25519.PrivateKey.
func PEMEncodePrivateKey(key crypto.PrivateKey) ([]byte, error) {
var pemType string
var keyBytes []byte
switch key := key.(type) {
case *ecdsa.PrivateKey:
var err error
pemType = "EC"
keyBytes, err = x509.MarshalECPrivateKey(key)
if err != nil {
return nil, err
}
case *rsa.PrivateKey:
pemType = "RSA"
keyBytes = x509.MarshalPKCS1PrivateKey(key)
case ed25519.PrivateKey:
var err error
pemType = "ED25519"
keyBytes, err = x509.MarshalPKCS8PrivateKey(key)
if err != nil {
return nil, err
}
default:
return nil, fmt.Errorf("unsupported key type: %T", key)
}
pemKey := pem.Block{Type: pemType + " PRIVATE KEY", Bytes: keyBytes}
return pem.EncodeToMemory(&pemKey), nil
}
// PEMDecodePrivateKey loads a PEM-encoded ECC/RSA private key from an array of bytes.
// Borrowed from Go standard library, to handle various private key and PEM block types.
func PEMDecodePrivateKey(keyPEMBytes []byte) (crypto.Signer, error) {
// Modified from original:
// https://github.com/golang/go/blob/693748e9fa385f1e2c3b91ca9acbb6c0ad2d133d/src/crypto/tls/tls.go#L291-L308
// https://github.com/golang/go/blob/693748e9fa385f1e2c3b91ca9acbb6c0ad2d133d/src/crypto/tls/tls.go#L238
keyBlockDER, _ := pem.Decode(keyPEMBytes)
if keyBlockDER == nil {
return nil, fmt.Errorf("failed to decode PEM block containing private key")
}
if keyBlockDER.Type != "PRIVATE KEY" && !strings.HasSuffix(keyBlockDER.Type, " PRIVATE KEY") {
return nil, fmt.Errorf("unknown PEM header %q", keyBlockDER.Type)
}
if key, err := x509.ParsePKCS1PrivateKey(keyBlockDER.Bytes); err == nil {
return key, nil
}
if key, err := x509.ParsePKCS8PrivateKey(keyBlockDER.Bytes); err == nil {
switch key := key.(type) {
case *rsa.PrivateKey, *ecdsa.PrivateKey, ed25519.PrivateKey:
return key.(crypto.Signer), nil
default:
return nil, fmt.Errorf("found unknown private key type in PKCS#8 wrapping: %T", key)
}
}
if key, err := x509.ParseECPrivateKey(keyBlockDER.Bytes); err == nil {
return key, nil
}
return nil, fmt.Errorf("unknown private key type")
}
// parseCertsFromPEMBundle parses a certificate bundle from top to bottom and returns
// a slice of x509 certificates. This function will error if no certificates are found.
func parseCertsFromPEMBundle(bundle []byte) ([]*x509.Certificate, error) {
var certificates []*x509.Certificate
var certDERBlock *pem.Block
for {
certDERBlock, bundle = pem.Decode(bundle)
if certDERBlock == nil {
break
}
if certDERBlock.Type == "CERTIFICATE" {
cert, err := x509.ParseCertificate(certDERBlock.Bytes)
if err != nil {
return nil, err
}
certificates = append(certificates, cert)
}
}
if len(certificates) == 0 {
return nil, fmt.Errorf("no certificates found in bundle")
}
return certificates, nil
}
// fastHash hashes input using a hashing algorithm that
// is fast, and returns the hash as a hex-encoded string.
// Do not use this for cryptographic purposes.
func fastHash(input []byte) string {
h := fnv.New32a()
h.Write(input)
return fmt.Sprintf("%x", h.Sum32())
}
// saveCertResource saves the certificate resource to disk. This
// includes the certificate file itself, the private key, and the
// metadata file.
func (cfg *Config) saveCertResource(ctx context.Context, issuer Issuer, cert CertificateResource) error {
metaBytes, err := json.MarshalIndent(cert, "", "\t")
if err != nil {
return fmt.Errorf("encoding certificate metadata: %v", err)
}
issuerKey := issuer.IssuerKey()
certKey := cert.NamesKey()
all := []keyValue{
{
key: StorageKeys.SitePrivateKey(issuerKey, certKey),
value: cert.PrivateKeyPEM,
},
{
key: StorageKeys.SiteCert(issuerKey, certKey),
value: cert.CertificatePEM,
},
{
key: StorageKeys.SiteMeta(issuerKey, certKey),
value: metaBytes,
},
}
return storeTx(ctx, cfg.Storage, all)
}
// loadCertResourceAnyIssuer loads and returns the certificate resource from any
// of the configured issuers. If multiple are found (e.g. if there are 3 issuers
// configured, and all 3 have a resource matching certNamesKey), then the newest
// (latest NotBefore date) resource will be chosen.
func (cfg *Config) loadCertResourceAnyIssuer(ctx context.Context, certNamesKey string) (CertificateResource, error) {
// we can save some extra decoding steps if there's only one issuer, since
// we don't need to compare potentially multiple available resources to
// select the best one, when there's only one choice anyway
if len(cfg.Issuers) == 1 {
return cfg.loadCertResource(ctx, cfg.Issuers[0], certNamesKey)
}
type decodedCertResource struct {
CertificateResource
issuer Issuer
decoded *x509.Certificate
}
var certResources []decodedCertResource
var lastErr error
// load and decode all certificate resources found with the
// configured issuers so we can sort by newest
for _, issuer := range cfg.Issuers {
certRes, err := cfg.loadCertResource(ctx, issuer, certNamesKey)
if err != nil {
if errors.Is(err, fs.ErrNotExist) {
// not a problem, but we need to remember the error
// in case we end up not finding any cert resources
// since we'll need an error to return in that case
lastErr = err
continue
}
return CertificateResource{}, err
}
certs, err := parseCertsFromPEMBundle(certRes.CertificatePEM)
if err != nil {
return CertificateResource{}, err
}
certResources = append(certResources, decodedCertResource{
CertificateResource: certRes,
issuer: issuer,
decoded: certs[0],
})
}
if len(certResources) == 0 {
if lastErr == nil {
lastErr = fmt.Errorf("no certificate resources found") // just in case; e.g. no Issuers configured
}
return CertificateResource{}, lastErr
}
// sort by date so the most recently issued comes first
sort.Slice(certResources, func(i, j int) bool {
return certResources[j].decoded.NotBefore.Before(certResources[i].decoded.NotBefore)
})
cfg.Logger.Debug("loading managed certificate",
zap.String("domain", certNamesKey),
zap.Time("expiration", expiresAt(certResources[0].decoded)),
zap.String("issuer_key", certResources[0].issuer.IssuerKey()),
zap.Any("storage", cfg.Storage),
)
return certResources[0].CertificateResource, nil
}
// loadCertResource loads a certificate resource from the given issuer's storage location.
func (cfg *Config) loadCertResource(ctx context.Context, issuer Issuer, certNamesKey string) (CertificateResource, error) {
certRes := CertificateResource{issuerKey: issuer.IssuerKey()}
normalizedName, err := idna.ToASCII(certNamesKey)
if err != nil {
return CertificateResource{}, fmt.Errorf("converting '%s' to ASCII: %v", certNamesKey, err)
}
keyBytes, err := cfg.Storage.Load(ctx, StorageKeys.SitePrivateKey(certRes.issuerKey, normalizedName))
if err != nil {
return CertificateResource{}, err
}
certRes.PrivateKeyPEM = keyBytes
certBytes, err := cfg.Storage.Load(ctx, StorageKeys.SiteCert(certRes.issuerKey, normalizedName))
if err != nil {
return CertificateResource{}, err
}
certRes.CertificatePEM = certBytes
metaBytes, err := cfg.Storage.Load(ctx, StorageKeys.SiteMeta(certRes.issuerKey, normalizedName))
if err != nil {
return CertificateResource{}, err
}
err = json.Unmarshal(metaBytes, &certRes)
if err != nil {
return CertificateResource{}, fmt.Errorf("decoding certificate metadata: %v", err)
}
return certRes, nil
}
// hashCertificateChain computes the unique hash of certChain,
// which is the chain of DER-encoded bytes. It returns the
// hex encoding of the hash.
func hashCertificateChain(certChain [][]byte) string {
h := sha256.New()
for _, certInChain := range certChain {
h.Write(certInChain)
}
return fmt.Sprintf("%x", h.Sum(nil))
}
func namesFromCSR(csr *x509.CertificateRequest) []string {
var nameSet []string
nameSet = append(nameSet, csr.DNSNames...)
nameSet = append(nameSet, csr.EmailAddresses...)
for _, v := range csr.IPAddresses {
nameSet = append(nameSet, v.String())
}
for _, v := range csr.URIs {
nameSet = append(nameSet, v.String())
}
return nameSet
}
// preferredDefaultCipherSuites returns an appropriate
// cipher suite to use depending on hardware support
// for AES-NI.
//
// See https://github.com/mholt/caddy/issues/1674
func preferredDefaultCipherSuites() []uint16 {
if cpuid.CPU.Supports(cpuid.AESNI) {
return defaultCiphersPreferAES
}
return defaultCiphersPreferChaCha
}
var (
defaultCiphersPreferAES = []uint16{
tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
}
defaultCiphersPreferChaCha = []uint16{
tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
}
)
// StandardKeyGenerator is the standard, in-memory key source
// that uses crypto/rand.
type StandardKeyGenerator struct {
// The type of keys to generate.
KeyType KeyType
}
// GenerateKey generates a new private key according to kg.KeyType.
func (kg StandardKeyGenerator) GenerateKey() (crypto.PrivateKey, error) {
switch kg.KeyType {
case ED25519:
_, priv, err := ed25519.GenerateKey(rand.Reader)
return priv, err
case "", P256:
return ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
case P384:
return ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
case RSA2048:
return rsa.GenerateKey(rand.Reader, 2048)
case RSA4096:
return rsa.GenerateKey(rand.Reader, 4096)
case RSA8192:
return rsa.GenerateKey(rand.Reader, 8192)
}
return nil, fmt.Errorf("unrecognized or unsupported key type: %s", kg.KeyType)
}
// DefaultKeyGenerator is the default key source.
var DefaultKeyGenerator = StandardKeyGenerator{KeyType: P256}
// KeyType enumerates the known/supported key types.
type KeyType string
// Constants for all key types we support.
const (
ED25519 = KeyType("ed25519")
P256 = KeyType("p256")
P384 = KeyType("p384")
RSA2048 = KeyType("rsa2048")
RSA4096 = KeyType("rsa4096")
RSA8192 = KeyType("rsa8192")
)