cacert-gosigner/internal/x509/revoking/revoking.go

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2022-04-24 07:25:04 +00:00
/*
Copyright 2021-2022 CAcert Inc.
SPDX-License-Identifier: Apache-2.0
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 revoking takes care of handling certificate revocation requests.
package revoking
import (
"crypto"
"crypto/rand"
"crypto/x509"
"crypto/x509/pkix"
"encoding/asn1"
"fmt"
"math/big"
"strings"
"time"
"github.com/balacode/go-delta"
"github.com/sirupsen/logrus"
)
var OidCRLReason = asn1.ObjectIdentifier{2, 5, 29, 21}
const defaultCRLValidity = 24 * time.Hour
type CRLReason int
// CRL reason codes as defined in RFC 5280 section 5.3.1
const (
CRLReasonUnspecified CRLReason = 0
CRLReasonKeyCompromise CRLReason = 1
CRLReasonCACompromise CRLReason = 2
CRLReasonAffiliationChanged CRLReason = 3
CRLReasonSuperseded CRLReason = 4
CRLReasonCessationOfOperation CRLReason = 5
CRLReasonCertificateHold CRLReason = 6
CRLReasonRemoveFromCRL CRLReason = 8
CRLReasonPrivilegeWithdrawn CRLReason = 9
CRLReasonAACompromise CRLReason = 10
)
var crlReasonNames = map[CRLReason]string{
CRLReasonUnspecified: "unspecified",
CRLReasonKeyCompromise: "keyCompromise",
CRLReasonCACompromise: "CACompromise",
CRLReasonAffiliationChanged: "affiliationChanged",
CRLReasonSuperseded: "superseded",
CRLReasonCessationOfOperation: "cessationOfOperation",
CRLReasonCertificateHold: "certificateHold",
CRLReasonRemoveFromCRL: "removeFromCRL",
CRLReasonPrivilegeWithdrawn: "privilegeWithdrawn",
CRLReasonAACompromise: "AACompromise",
}
func (r CRLReason) String() string {
if reason, ok := crlReasonNames[r]; ok {
return reason
}
return crlReasonNames[CRLReasonUnspecified]
}
func (r CRLReason) BuildExtension() pkix.Extension {
extBytes, _ := asn1.Marshal(r)
return pkix.Extension{Id: OidCRLReason, Value: extBytes}
}
// ParseReason takes a reason string and performs a case-insensitive match to a reason code
func ParseReason(rs string) CRLReason {
for key, name := range crlReasonNames {
if strings.EqualFold(name, rs) {
return key
}
}
return CRLReasonUnspecified
}
type X509Revoking struct {
repository Repository
crlAlgorithm x509.SignatureAlgorithm
crlIssuer *x509.Certificate
signer crypto.Signer
logger *logrus.Logger
}
type RevokeCertificate struct {
serialNumber *big.Int
reason CRLReason
}
func NewRevokeCertificate(serialNumber *big.Int, reason CRLReason) *RevokeCertificate {
return &RevokeCertificate{
serialNumber: serialNumber,
reason: reason,
}
}
type CRLInformation struct {
CRL []byte // DER encoded CRL
Number *big.Int
NextUpdate time.Time
}
func (r *X509Revoking) Revoke(revokeCertificate *RevokeCertificate) (*pkix.RevokedCertificate, error) {
revoked := &pkix.RevokedCertificate{
SerialNumber: revokeCertificate.serialNumber,
RevocationTime: time.Now(),
Extensions: []pkix.Extension{revokeCertificate.reason.BuildExtension()},
}
if err := r.repository.StoreRevocation(revoked); err != nil {
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return nil, fmt.Errorf("could not store revocation %w", err)
}
return revoked, nil
}
func (r *X509Revoking) createCRL() (*CRLInformation, error) {
revoked, err := r.repository.RevokedCertificates()
if err != nil {
return nil, fmt.Errorf("could not get revocation information: %w", err)
}
nextNumber, err := r.repository.NextCRLNumber()
if err != nil {
return nil, fmt.Errorf("could not get next CRL number: %w", err)
}
nextUpdate := time.Now().UTC().Add(defaultCRLValidity)
list, err := x509.CreateRevocationList(rand.Reader, &x509.RevocationList{
SignatureAlgorithm: r.crlAlgorithm,
RevokedCertificates: revoked,
Number: nextNumber,
ThisUpdate: time.Now().UTC(),
NextUpdate: nextUpdate,
}, r.crlIssuer, r.signer)
if err != nil {
return nil, fmt.Errorf("could not sign revocation list: %w", err)
}
err = r.repository.StoreCRL(nextNumber, list)
if err != nil {
return nil, fmt.Errorf("could not store new CRL: %w", err)
}
return &CRLInformation{CRL: list, Number: nextNumber, NextUpdate: nextUpdate}, nil
}
func (r *X509Revoking) GetCurrentCRL() (*CRLInformation, error) {
return r.GetCRL(nil)
}
const maximumCRLLifetime = 6 * time.Hour
func (r *X509Revoking) GetCRL(number *big.Int) (*CRLInformation, error) {
var (
crl []byte
err error
list *x509.RevocationList
)
crl, err = r.repository.LoadCRL(number)
if err != nil {
r.logger.WithError(err).Warn("could not load CRL")
if number != nil {
return nil, fmt.Errorf("could not load crl number 0x%0x", number)
}
}
if crl != nil {
list, err = x509.ParseRevocationList(crl)
if err != nil {
r.logger.WithError(err).Warn("could not parse CRL")
}
stillValid := list.ThisUpdate.Add(maximumCRLLifetime).After(time.Now().UTC())
if number != nil || stillValid {
return &CRLInformation{CRL: crl, Number: list.Number, NextUpdate: list.NextUpdate}, nil
}
}
return r.createCRL()
}
func NewX509Revoking(
repo Repository,
crlAlgorithm x509.SignatureAlgorithm,
issuer *x509.Certificate,
signer crypto.Signer,
logger *logrus.Logger,
) *X509Revoking {
return &X509Revoking{
repository: repo,
crlAlgorithm: crlAlgorithm,
crlIssuer: issuer,
signer: signer,
logger: logger,
}
}
type Result struct {
CRLData []byte
IsDelta bool
Number *big.Int
}
type FetchCRLHandler struct {
repositories map[string]*X509Revoking
}
func NewFetchCRLHandler(repositories map[string]*X509Revoking) *FetchCRLHandler {
return &FetchCRLHandler{repositories: repositories}
}
func (h *FetchCRLHandler) FetchCRL(issuerID string, crlNumber *big.Int) (*Result, error) {
var (
currentCRL, oldCRL *CRLInformation
err error
)
repo, ok := h.repositories[issuerID]
if !ok {
return nil, fmt.Errorf("unknown issuer ID %s", issuerID)
}
if repo.signer == nil {
return nil, fmt.Errorf("key for issuer ID %s is not available", issuerID)
}
currentCRL, err = repo.GetCurrentCRL()
if err != nil {
return nil, fmt.Errorf("could not get CRL for issuer ID %s: %w", issuerID, err)
}
if crlNumber == nil {
return &Result{CRLData: currentCRL.CRL, Number: currentCRL.Number, IsDelta: false}, nil
}
if crlNumber.Cmp(currentCRL.Number) == 0 {
return &Result{CRLData: nil, Number: currentCRL.Number, IsDelta: false}, nil
}
oldCRL, err = repo.GetCRL(crlNumber)
if err != nil {
return &Result{CRLData: currentCRL.CRL, Number: currentCRL.Number, IsDelta: false}, nil
}
diff := delta.Make(oldCRL.CRL, currentCRL.CRL)
patchBytes := diff.Bytes()
if len(patchBytes) > len(currentCRL.CRL) {
return &Result{CRLData: currentCRL.CRL, Number: currentCRL.Number, IsDelta: false}, nil
}
return &Result{CRLData: patchBytes, Number: currentCRL.Number, IsDelta: true}, nil
}