Start implementation of revoke action

datastructures/common.go

@@ -2,7 +2,9 @@ package datastructures
 
 import "encoding/binary"
 
-func encode24BitLength(data []byte) []byte {
+const signerTimeFormat = "010203042006.05"
+
+func Encode24BitLength(data []byte) []byte {
 	lengthBytes := make([]byte, 4)
 	binary.BigEndian.PutUint32(lengthBytes, uint32(len(data)))
 	return lengthBytes[1:]

datastructures/signerrequest.go

@@ -3,23 +3,24 @@ package datastructures
 import (
 	"bytes"
 	"encoding/binary"
+	"fmt"
 	"time"
 
 	"git.cacert.org/cacert-gosigner/shared"
 )
 
 type SignerRequest struct {
-	Version       uint8
+	Version     uint8
-	Action        shared.Action
+	Action      shared.Action
-	System        uint8
+	System      shared.CryptoSystemId
-	Root          uint8
+	Root        shared.CryptoSystemRootId
-	Configuration uint8
+	Profile     shared.CertificateProfileId
-	Parameter1    uint8
+	MdAlgorithm shared.MessageDigestAlgorithmId
-	Parameter2    uint16
+	Days        uint16
-	Parameter3    uint8
+	Spkac       uint8
-	Content1      string
+	Content1    string
-	Content2      string
+	Content2    string
-	Content3      string
+	Content3    string
 }
 
 func SignerRequestFromData(blockData []byte) (*SignerRequest, error) {
@@ -39,42 +40,66 @@ func SignerRequestFromData(blockData []byte) (*SignerRequest, error) {
 	content3 := string(contentBytes[3+content3Offset : 3+content3Offset+content3Length])
 
 	return &SignerRequest{
-		Version:       headerBytes[0],
+		Version:     headerBytes[0],
-		Action:        shared.Action(headerBytes[1]),
+		Action:      shared.Action(headerBytes[1]),
-		System:        headerBytes[2],
+		System:      shared.CryptoSystemId(headerBytes[2]),
-		Root:          headerBytes[3],
+		Root:        shared.CryptoSystemRootId(headerBytes[3]),
-		Configuration: headerBytes[4],
+		Profile:     shared.CertificateProfileId(headerBytes[4]),
-		Parameter1:    headerBytes[5],
+		MdAlgorithm: shared.MessageDigestAlgorithmId(headerBytes[5]),
-		Parameter2:    binary.BigEndian.Uint16([]byte{headerBytes[6], headerBytes[7]}),
+		Days:        binary.BigEndian.Uint16([]byte{headerBytes[6], headerBytes[7]}),
-		Parameter3:    headerBytes[8],
+		Spkac:       headerBytes[8],
-		Content1:      content1,
+		Content1:    content1,
-		Content2:      content2,
+		Content2:    content2,
-		Content3:      content3,
+		Content3:    content3,
 	}, nil
 }
 
-func (r SignerRequest) Serialize() []byte {
+func (r *SignerRequest) Serialize() []byte {
 	parameter2Bytes := make([]byte, 2)
-	binary.BigEndian.PutUint16(parameter2Bytes, r.Parameter2)
+	binary.BigEndian.PutUint16(parameter2Bytes, r.Days)
 	headerBytes := bytes.Join([][]byte{
-		{r.Version, byte(r.Action), r.System, r.Root, r.Configuration, r.Parameter1},
+		{
-		parameter2Bytes, {r.Parameter3}}, []byte{})
+			r.Version,
+			byte(r.Action),
+			byte(r.System),
+			byte(r.Root),
+			byte(r.Profile),
+			byte(r.MdAlgorithm),
+		},
+		parameter2Bytes, {r.Spkac}}, []byte{})
 	content1Bytes := []byte(r.Content1)
 	content2Bytes := []byte(r.Content2)
 	content3Bytes := []byte(r.Content3)
 	blockBytes := bytes.Join([][]byte{
-		encode24BitLength(headerBytes), headerBytes,
+		Encode24BitLength(headerBytes), headerBytes,
-		encode24BitLength(content1Bytes), content1Bytes,
+		Encode24BitLength(content1Bytes), content1Bytes,
-		encode24BitLength(content2Bytes), content2Bytes,
+		Encode24BitLength(content2Bytes), content2Bytes,
-		encode24BitLength(content3Bytes), content3Bytes,
+		Encode24BitLength(content3Bytes), content3Bytes,
 	}, []byte{})
-	return bytes.Join([][]byte{encode24BitLength(blockBytes), blockBytes}, []byte{})
+	return bytes.Join([][]byte{Encode24BitLength(blockBytes), blockBytes}, []byte{})
+}
+
+func (r *SignerRequest) String() string {
+	return fmt.Sprintf(
+		"v:%d %s s:%d r:%d p:%d md:%d days:%d spkac:%d '%s' '%s' '%s'",
+		r.Version,
+		r.Action,
+		r.System,
+		r.Root,
+		r.Profile,
+		r.MdAlgorithm,
+		r.Days,
+		r.Spkac,
+		r.Content1,
+		r.Content2,
+		r.Content3,
+	)
 }
 
 func NewNulRequest() *SignerRequest {
 	return &SignerRequest{
 		Version:  shared.ProtocolVersion,
 		Action:   shared.ActionNul,
-		Content1: time.Now().UTC().Format("010203042006.05"),
+		Content1: time.Now().UTC().Format(signerTimeFormat),
 	}
 }

datastructures/signerresponse.go

@@ -62,10 +62,20 @@ func (r SignerResponse) Serialize() []byte {
 	content2Bytes := []byte(r.Content2)
 	content3Bytes := []byte(r.Content3)
 	blockBytes := bytes.Join([][]byte{
-		encode24BitLength(headerBytes), headerBytes,
+		Encode24BitLength(headerBytes), headerBytes,
-		encode24BitLength(content1Bytes), content1Bytes,
+		Encode24BitLength(content1Bytes), content1Bytes,
-		encode24BitLength(content2Bytes), content2Bytes,
+		Encode24BitLength(content2Bytes), content2Bytes,
-		encode24BitLength(content3Bytes), content3Bytes,
+		Encode24BitLength(content3Bytes), content3Bytes,
 	}, []byte{})
-	return bytes.Join([][]byte{encode24BitLength(blockBytes), blockBytes}, []byte{})
+	return bytes.Join([][]byte{Encode24BitLength(blockBytes), blockBytes}, []byte{})
+}
+
+func NewNulResponse(version byte) *SignerResponse {
+	return &SignerResponse{
+		Version:  version,
+		Action:   shared.ActionNul,
+		Content1: "",
+		Content2: "",
+		Content3: "",
+	}
 }

go.mod

@@ -5,5 +5,6 @@ go 1.15
 require (
 	github.com/sirupsen/logrus v1.7.0
 	go.bug.st/serial v1.1.1
+	golang.org/x/sys v0.0.0-20200909081042-eff7692f9009
 	gopkg.in/yaml.v2 v2.4.0
 )

shared/shared.go

@@ -14,7 +14,7 @@ const (
 	TrailerFieldSize  = len(MagicTrailer)
 )
 
-type Action uint8
+type Action byte
 
 const (
 	ActionNul    = Action(0)
@@ -34,3 +34,11 @@ func (a Action) String() string {
 		return "unknown"
 	}
 }
+
+type CryptoSystemRootId byte
+
+type CertificateProfileId byte
+
+type MessageDigestAlgorithmId byte
+
+type CryptoSystemId byte

signer/command_processor.go

@@ -1,8 +1,19 @@
 package signer
 
 import (
+	"bytes"
+	"crypto/rand"
+	"crypto/sha1"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/hex"
+	"encoding/pem"
 	"errors"
 	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"time"
 	"unsafe"
 
 	log "github.com/sirupsen/logrus"
@@ -12,28 +23,45 @@ import (
 	"git.cacert.org/cacert-gosigner/shared"
 )
 
+const crlLifetime = time.Hour * 24 * 7
+
+var emptyDataSha1 [20]byte
+
+func init() {
+	emptyDataSha1 = sha1.Sum([]byte{})
+}
+
+type CommandProcessorSettings struct {
+	CABaseDir       string
+	XDeltaPath      string
+	OpenPGPUidEmail string
+}
+
 // The CommandProcessor takes parsed protocol data and executes the actual
 // functionality.
 type CommandProcessor struct {
+	Settings      *CommandProcessorSettings
+	CryptoSystems map[shared.CryptoSystemId]*CryptoSystem
 }
 
 // Process the signer request
-func (p *CommandProcessor) Process(command datastructures.SignerRequest) (
+func (p *CommandProcessor) Process(command *datastructures.SignerRequest) (
-	response *datastructures.SignerResponse,
+	*datastructures.SignerResponse,
-	err error,
+	error,
 ) {
-	log.Infof("analyze %+v", command)
+	log.Infof("process %s", command)
+
+	if command.Version != shared.ProtocolVersion {
+		return nil, fmt.Errorf("unsupported protocol version %d", command.Version)
+	}
 
 	switch command.Action {
 	case shared.ActionNul:
-		response, err = p.handleNulAction(command)
+		return p.handleNulAction(command)
-		return
 	case shared.ActionSign:
-		response, err = p.handleSignAction(command)
+		return p.handleSignAction(command)
-		return
 	case shared.ActionRevoke:
-		response, err = p.handleRevokeAction(command)
+		return p.handleRevokeAction(command)
-		return
 	default:
 		return nil, errors.New(fmt.Sprintf(
 			"unsupported Action 0x%02x %s",
@@ -43,7 +71,7 @@ func (p *CommandProcessor) Process(command datastructures.SignerRequest) (
 	}
 }
 
-func (*CommandProcessor) handleNulAction(command datastructures.SignerRequest) (
+func (*CommandProcessor) handleNulAction(command *datastructures.SignerRequest) (
 	*datastructures.SignerResponse,
 	error,
 ) {
@@ -64,13 +92,11 @@ func (*CommandProcessor) handleNulAction(command datastructures.SignerRequest) (
 		log.Errorf("could not set system time: %v", e1)
 	}
 
-	return &datastructures.SignerResponse{
+	return datastructures.NewNulResponse(command.Version), nil
-		Version: command.Version, Action: command.Action,
-		Content1: "", Content2: "", Content3: ""}, nil
 }
 
 func (p *CommandProcessor) handleSignAction(
-	command datastructures.SignerRequest,
+	command *datastructures.SignerRequest,
 ) (
 	*datastructures.SignerResponse,
 	error,
@@ -80,11 +106,239 @@ func (p *CommandProcessor) handleSignAction(
 }
 
 func (p *CommandProcessor) handleRevokeAction(
-	command datastructures.SignerRequest,
+	command *datastructures.SignerRequest,
 ) (
 	*datastructures.SignerResponse,
 	error,
 ) {
 	log.Debugf("handle revoke call: %v", command)
+
+	idSystem, err := p.checkIdentitySystem(
+		command.System,
+		command.Root,
+		command.Profile,
+		command.MdAlgorithm,
+	)
+	if err != nil {
+		return nil, err
+	}
+	log.Debugf("identified id system: %+v", idSystem)
+
+	switch command.System {
+	case CsX509:
+		request := command.Content1
+		clientHash := command.Content3
+		return p.revokeX509(idSystem, request, clientHash)
+	default:
+		return nil, fmt.Errorf("revoke not implemented for crypto system %s", idSystem.System)
+	}
+}
+
+type IdSystemParameters struct {
+	System                 *CryptoSystem
+	Root                   *RootCredentials
+	RootId                 shared.CryptoSystemRootId
+	Profile                string
+	MessageDigestAlgorithm x509.SignatureAlgorithm
+}
+
+func (p *CommandProcessor) checkIdentitySystem(
+	systemId shared.CryptoSystemId,
+	rootId shared.CryptoSystemRootId,
+	profileId shared.CertificateProfileId,
+	algorithmId shared.MessageDigestAlgorithmId,
+) (*IdSystemParameters, error) {
+	cryptoSystem, ok := p.CryptoSystems[systemId]
+	if !ok {
+		return nil, fmt.Errorf(
+			"unsupported crypto system %d",
+			systemId,
+		)
+	}
+	root, ok := p.CryptoSystems[systemId].Roots[rootId]
+	if !ok {
+		return nil, fmt.Errorf(
+			"unsupported root certificate %d for crypto system %s",
+			rootId,
+			cryptoSystem,
+		)
+	}
+	profile, ok := p.CryptoSystems[systemId].Profiles[profileId]
+	if !ok {
+		return nil, fmt.Errorf(
+			"invalid CA profile %d for crypto system %s",
+			profileId,
+			cryptoSystem,
+		)
+	}
+	mdAlgorithm, ok := p.CryptoSystems[systemId].DigestAlgorithms[algorithmId]
+	if !ok {
+		return nil, fmt.Errorf(
+			"unsupported digest algorithm %d for crypto system %s",
+			algorithmId,
+			cryptoSystem,
+		)
+	}
+	return &IdSystemParameters{
+		System:                 cryptoSystem,
+		Root:                   root,
+		RootId:                 rootId,
+		Profile:                profile,
+		MessageDigestAlgorithm: mdAlgorithm,
+	}, nil
+}
+
+func (p *CommandProcessor) revokeX509(
+	system *IdSystemParameters,
+	request string,
+	clientHash string,
+) (*datastructures.SignerResponse, error) {
+	clientHashBytes, err := hex.DecodeString(clientHash)
+	if err != nil {
+		return nil, fmt.Errorf("could not parse '%s' as hex bytes", clientHash)
+	}
+
+	log.Debugf("revoke X.509 for root %s (%d)", system.Root, system.RootId)
+	log.Debugf("hash bytes from client %x", clientHashBytes)
+
+	crlFileName := fmt.Sprintf("revoke-root%d.crl", system.RootId)
+	stat, err := os.Stat(crlFileName)
+	if err != nil {
+		log.Debugf("CRL file %s does not exist", crlFileName)
+	} else if stat.IsDir() {
+		return nil, fmt.Errorf("CRL filename %s points to a directory", crlFileName)
+	}
+
+	currentHash := emptyDataSha1
+	if stat != nil {
+		crlData, err := ioutil.ReadFile(crlFileName)
+		if err != nil {
+			log.Warnf("could not read current CRL, assuming empty CRL")
+		}
+		currentHash = sha1.Sum(crlData)
+	}
+	log.Debugf("hash bytes on signer %x", currentHash)
+
+	crlIsCurrent := false
+	if bytes.Equal(clientHashBytes, currentHash[:]) {
+		log.Debug("client CRL hash and current CRL hash on signer match")
+		err := p.deleteOldCrl(system.RootId, clientHash)
+		if err != nil {
+			log.Warnf("could not delete old CRLs: %v", err)
+		}
+		if !bytes.Equal(clientHashBytes, emptyDataSha1[:]) {
+			crlIsCurrent = true
+		} else {
+			log.Debugf("client has an empty CRL, the signer too")
+		}
+	}
+
+	if len(request) > 0 {
+		_, err = revokeCertificate(request, system.System, system.RootId)
+		if err != nil {
+			return nil, fmt.Errorf("could not revoke certificate / create CRL: %v", err)
+		}
+	}
+
+	var crlBytes []byte
+	crlBytes, err = generateCrl(system.MessageDigestAlgorithm, system.System, system.RootId)
+	if err != nil {
+		return nil, fmt.Errorf("could not generate a new CRL for root %d: %v", system.RootId, err)
+	}
+	log.Debugf("crlIsCurrent: %v, crlBytes: %d", crlIsCurrent, len(crlBytes))
+
+	log.Tracef("New CRL\n%s", pem.EncodeToMemory(&pem.Block{
+		Type:  "X509 CRL",
+		Bytes: crlBytes,
+	}))
+
+	err = ioutil.WriteFile(crlFileName, crlBytes, 0644)
+	if err != nil {
+		return nil, fmt.Errorf("could not write new CRL to %s: %v", crlFileName, err)
+	}
+
 	return nil, errors.New("not implemented yet")
 }
+
+func (p *CommandProcessor) deleteOldCrl(id shared.CryptoSystemRootId, hash string) error {
+	path.Join(p.Settings.CABaseDir, "currentcrls", fmt.Sprintf("%d", id))
+	// TODO: implement
+	return errors.New("not implemented yet")
+}
+
+func generateCrl(
+	algorithm x509.SignatureAlgorithm,
+	system *CryptoSystem,
+	rootId shared.CryptoSystemRootId,
+) ([]byte, error) {
+	caCertificate, err := system.loadCertificate(rootId)
+	if err != nil {
+		return nil, err
+	}
+	caPrivateKey, err := system.getPrivateKey(rootId)
+	if err != nil {
+		return nil, err
+	}
+	certificatesToRevoke, err := system.loadRevokedCertificatesFromDatabase(rootId)
+	if err != nil {
+		return nil, err
+	}
+	nextCrlNumber, err := system.getNextCRLNumber(rootId)
+	if err != nil {
+		return nil, err
+	}
+	crlTemplate := &x509.RevocationList{
+		SignatureAlgorithm:  algorithm,
+		RevokedCertificates: certificatesToRevoke,
+		Number:              nextCrlNumber,
+		ThisUpdate:          time.Now(),
+		NextUpdate:          time.Now().Add(crlLifetime),
+		ExtraExtensions:     nil,
+	}
+
+	defer func() {
+		if err = system.bumpCRLNumber(rootId, nextCrlNumber); err != nil {
+			log.Errorf("could not bump CRL number: %v", err)
+		}
+	}()
+
+	return x509.CreateRevocationList(
+		rand.Reader,
+		crlTemplate,
+		caCertificate,
+		caPrivateKey,
+	)
+}
+
+func revokeCertificate(request string, system *CryptoSystem, rootId shared.CryptoSystemRootId) (*pkix.RevokedCertificate, error) {
+	pemBlock, _ := pem.Decode([]byte(request))
+	if pemBlock.Type != "CERTIFICATE" {
+		if pemBlock.Type != "CERTIFICATE" {
+			log.Warnf(
+				"PEM structure is probably not a certificate. PEM block has type %s",
+				pemBlock.Type,
+			)
+			log.Trace(request)
+		}
+	}
+	certificate, err := x509.ParseCertificate(pemBlock.Bytes)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"could no parse certificate: %v",
+			err,
+		)
+	}
+	return system.recordRevocation(rootId, certificate)
+}
+
+func NewCommandProcessorSettings() *CommandProcessorSettings {
+	caBasedir, ok := os.LookupEnv("SIGNER_BASEDIR")
+	if !ok {
+		caBasedir = "."
+	}
+	gpgUidEmail, ok := os.LookupEnv("SIGNER_GPG_KEYRING_DIR")
+	if !ok {
+		gpgUidEmail = "gpg@cacert.org"
+	}
+	return &CommandProcessorSettings{CABaseDir: caBasedir, OpenPGPUidEmail: gpgUidEmail, XDeltaPath: "/usr/bin/xdelta"}
+}

signer/crypto_system.go

@@ -0,0 +1,251 @@
+package signer
+
+import (
+	"bufio"
+	"crypto"
+	"crypto/rsa"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"fmt"
+	"io/ioutil"
+	"math/big"
+	"os"
+	"path"
+	"strconv"
+	"strings"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+
+	"git.cacert.org/cacert-gosigner/shared"
+)
+
+type RootCredentials struct {
+	Name            string
+	PrivateKeyFile  string
+	PublicKeyFile   string
+	CertificateFile string
+	DatabaseFile    string
+	CRLNumber       string
+}
+
+type CryptoSystem struct {
+	Name             string
+	Roots            map[shared.CryptoSystemRootId]*RootCredentials
+	Profiles         map[shared.CertificateProfileId]string
+	DigestAlgorithms map[shared.MessageDigestAlgorithmId]x509.SignatureAlgorithm
+}
+
+func (system CryptoSystem) String() string {
+	return system.Name
+}
+
+func (system CryptoSystem) loadCertificate(rootId shared.CryptoSystemRootId) (*x509.Certificate, error) {
+	certificateFile := system.Roots[rootId].CertificateFile
+	pemBytes, err := ioutil.ReadFile(certificateFile)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"could not load certificate %s: %v",
+			certificateFile,
+			err,
+		)
+	}
+	pemBlock, _ := pem.Decode(pemBytes)
+	if pemBlock.Type != "CERTIFICATE" {
+		log.Warnf(
+			"PEM in %s is probably not a certificate. PEM block has type %s",
+			certificateFile,
+			pemBlock.Type,
+		)
+	}
+	certificate, err := x509.ParseCertificate(pemBlock.Bytes)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"could no parse certificate from %s: %v",
+			certificateFile,
+			err,
+		)
+	}
+	return certificate, nil
+}
+
+func (system CryptoSystem) getPrivateKey(rootId shared.CryptoSystemRootId) (crypto.Signer, error) {
+	privateKeyFile := system.Roots[rootId].PrivateKeyFile
+	pemBytes, err := ioutil.ReadFile(privateKeyFile)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"could not load private key %s: %v",
+			privateKeyFile,
+			err,
+		)
+	}
+	pemBlock, _ := pem.Decode(pemBytes)
+	if pemBlock.Type != "PRIVATE KEY" {
+		log.Warnf(
+			"PEM in %s is probably not a private key. PEM block has type %s",
+			privateKeyFile,
+			pemBlock.Type,
+		)
+	}
+	privateKey, err := x509.ParsePKCS8PrivateKey(pemBlock.Bytes)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"could no parse private key from %s: %v",
+			privateKeyFile,
+			err,
+		)
+	}
+	return privateKey.(*rsa.PrivateKey), nil
+}
+
+func (system *CryptoSystem) getNextCRLNumber(rootId shared.CryptoSystemRootId) (*big.Int, error) {
+	crlNumberFile := system.Roots[rootId].CRLNumber
+	_, err := os.Stat(crlNumberFile)
+	if err != nil {
+		log.Warnf("CRL number file %s does not exist: %v", crlNumberFile, err)
+		return big.NewInt(1), nil
+	}
+	data, err := ioutil.ReadFile(crlNumberFile)
+	if err != nil {
+		return nil, fmt.Errorf("could not read CRL number file %s", crlNumberFile)
+	}
+	result, err := stringAsBigInt(data)
+	if err != nil {
+		return nil, fmt.Errorf("could not parse content of %s as CRL number: %v", crlNumberFile, err)
+	}
+	return result, nil
+}
+
+func (system *CryptoSystem) bumpCRLNumber(rootId shared.CryptoSystemRootId, current *big.Int) error {
+	serial := current.Int64() + 1
+	crlNumberFile := system.Roots[rootId].CRLNumber
+	outFile, err := ioutil.TempFile(path.Dir(crlNumberFile), "*.txt")
+	defer func() { _ = outFile.Close() }()
+
+	_, err = outFile.WriteString(fmt.Sprintf(
+		"%s\n",
+		strings.ToUpper(strconv.FormatInt(serial, 16)),
+	))
+	if err != nil {
+		return fmt.Errorf("could not write new CRL number %d to %s: %v", serial, outFile.Name(), err)
+	}
+
+	if err = outFile.Close(); err != nil {
+		return fmt.Errorf("could not close temporary file %s: %v", outFile.Name(), err)
+	}
+	if err = os.Rename(crlNumberFile, fmt.Sprintf("%s.old", crlNumberFile)); err != nil {
+		return fmt.Errorf("could not rename %s to %s.old: %v", crlNumberFile, crlNumberFile, err)
+	}
+	if err = os.Rename(outFile.Name(), crlNumberFile); err != nil {
+		return fmt.Errorf("could not rename %s to %s: %v", outFile.Name(), crlNumberFile, err)
+	}
+	return nil
+}
+
+func stringAsBigInt(data []byte) (*big.Int, error) {
+	dataString := strings.TrimSpace(string(data))
+	parseInt, err := strconv.ParseInt(dataString, 16, 64)
+	if err != nil {
+		return nil, fmt.Errorf("could not parse %s as big int: %v", dataString, err)
+	}
+	return big.NewInt(parseInt), nil
+}
+
+func (system *CryptoSystem) loadRevokedCertificatesFromDatabase(rootId shared.CryptoSystemRootId) ([]pkix.RevokedCertificate, error) {
+	databaseFile := system.Roots[rootId].DatabaseFile
+	_, err := os.Stat(databaseFile)
+	if err != nil {
+		log.Warnf("openssl certificate database file %s does not exist: %v", databaseFile, err)
+		return []pkix.RevokedCertificate{}, nil
+	}
+	file, err := os.Open(databaseFile)
+	if err != nil {
+		return nil, fmt.Errorf("could not open openssl certificate database file %s: %v", databaseFile, err)
+	}
+	defer func() { _ = file.Close() }()
+
+	result := make([]pkix.RevokedCertificate, 0)
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := strings.Split(scanner.Text(), "\t")
+		if line[0] == "R" {
+			serialNumber, err := stringAsBigInt([]byte(line[3]))
+			if err != nil {
+				return nil, fmt.Errorf("could not parse serial number %s as big int: %v", line[3], err)
+			}
+			revokeTs, err := strconv.ParseInt(line[2][:len(line[2])-1], 10, 64)
+			result = append(result, pkix.RevokedCertificate{
+				SerialNumber:   serialNumber,
+				RevocationTime: time.Unix(revokeTs, 0),
+				Extensions:     nil,
+			})
+		}
+	}
+	return result, nil
+}
+
+func (system *CryptoSystem) recordRevocation(rootId shared.CryptoSystemRootId, certificate *x509.Certificate) (*pkix.RevokedCertificate, error) {
+	databaseFile := system.Roots[rootId].DatabaseFile
+	_, err := os.Stat(databaseFile)
+	if err != nil {
+		return nil, fmt.Errorf("openssl certificate database file %s does not exist: %v", databaseFile, err)
+	}
+	inFile, err := os.Open(databaseFile)
+	if err != nil {
+		return nil, fmt.Errorf("could not open openssl certificate database file %s: %v", databaseFile, err)
+	}
+	defer func() { _ = inFile.Close() }()
+
+	outFile, err := ioutil.TempFile(path.Dir(databaseFile), "*.txt")
+	defer func() { _ = outFile.Close() }()
+
+	scanner := bufio.NewScanner(inFile)
+	writer := bufio.NewWriter(outFile)
+
+	found := false
+	revocationTime := time.Now()
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		parts := strings.Split(line, "\t")
+		serialNumber, err := stringAsBigInt([]byte(parts[3]))
+		if err != nil {
+			return nil, fmt.Errorf("could not parse serial number %s as big int: %v", parts[3], err)
+		}
+		if serialNumber == certificate.SerialNumber {
+			line = strings.Join(
+				[]string{"R", parts[1], strconv.FormatInt(revocationTime.Unix(), 10) + "Z", parts[3], parts[4]},
+				"\t",
+			)
+			found = true
+		}
+		if _, err = writer.WriteString(fmt.Sprintf("%s\n", line)); err != nil {
+			return nil, fmt.Errorf("could not write '%s' to %s: %v", line, outFile.Name(), err)
+		}
+	}
+
+	if err = outFile.Close(); err != nil {
+		return nil, fmt.Errorf("could not close temporary file %s: %v", outFile.Name(), err)
+	}
+	if err = inFile.Close(); err != nil {
+		return nil, fmt.Errorf("could not close %s: %v", databaseFile, err)
+	}
+
+	if err = os.Rename(databaseFile, fmt.Sprintf("%s.old", databaseFile)); err != nil {
+		return nil, fmt.Errorf("could not rename %s to %s.old: %v", databaseFile, databaseFile, err)
+	}
+
+	if err = os.Rename(outFile.Name(), databaseFile); err != nil {
+		return nil, fmt.Errorf("could not rename temporary file %s to %s: %v", outFile.Name(), databaseFile, err)
+	}
+
+	if !found {
+		log.Warnf("entry not found in database")
+	}
+
+	return &pkix.RevokedCertificate{
+		SerialNumber:   certificate.SerialNumber,
+		RevocationTime: revocationTime,
+	}, nil
+}

signer/port_handler.go

@@ -43,7 +43,7 @@ func (p *PortHandler) MainLoop() {
 				return
 			}
 			log.Debugf("received command %v", command)
-			response, err := p.processor.Process(*command)
+			response, err := p.processor.Process(command)
 			if err != nil {
 				log.Errorf("error processing command: %v", err)
 				close(p.commandChan)
@@ -207,6 +207,6 @@ func NewSignerProcess(port io.ReadWriteCloser) *PortHandler {
 		port:        port,
 		errors:      errorChan,
 		commandChan: make(chan *datastructures.SignerRequest, 1),
-		processor:   &CommandProcessor{},
+		processor:   NewCommandProcessor(),
 	}
 }

signer/protocol_elements.go

@@ -0,0 +1,131 @@
+package signer
+
+import (
+	"crypto/x509"
+
+	"git.cacert.org/cacert-gosigner/shared"
+)
+
+const (
+	CsX509    shared.CryptoSystemId = 1
+	CsOpenPGP shared.CryptoSystemId = 2
+)
+
+const (
+	X509RootDefault shared.CryptoSystemRootId = 0
+	X509RootClass3  shared.CryptoSystemRootId = 1
+	X509RootClass3s shared.CryptoSystemRootId = 2
+	X509Root3       shared.CryptoSystemRootId = 3
+	X509Root4       shared.CryptoSystemRootId = 4
+	X509Root5       shared.CryptoSystemRootId = 5
+)
+
+const (
+	X509ProfileClient         shared.CertificateProfileId = 0
+	X509ProfileClientOrg      shared.CertificateProfileId = 1
+	X509ProfileClientCodesign shared.CertificateProfileId = 2
+	X509ProfileClientMachine  shared.CertificateProfileId = 3
+	X509ProfileClientAds      shared.CertificateProfileId = 4
+	X509ProfileServer         shared.CertificateProfileId = 5
+	X509ProfileServerOrg      shared.CertificateProfileId = 6
+	X509ProfileServerJabber   shared.CertificateProfileId = 7
+	X509ProfileOCSP           shared.CertificateProfileId = 8
+	X509ProfileTimestamp      shared.CertificateProfileId = 9
+	X509ProfileProxy          shared.CertificateProfileId = 10
+	X509ProfileSubCA          shared.CertificateProfileId = 11
+)
+
+const (
+	X509MDDefault   shared.MessageDigestAlgorithmId = 0
+	X509MDMd5       shared.MessageDigestAlgorithmId = 1
+	X509MDSha1      shared.MessageDigestAlgorithmId = 2
+	X509MDRipeMD160 shared.MessageDigestAlgorithmId = 3
+	X509MDSha256    shared.MessageDigestAlgorithmId = 8
+	X509MDSha384    shared.MessageDigestAlgorithmId = 9
+	X509MDSha512    shared.MessageDigestAlgorithmId = 10
+)
+
+const (
+	OpenPGPRoot0 shared.CryptoSystemRootId = 0
+)
+
+const (
+	OpenPGPDefaultProfile shared.CertificateProfileId = 0
+)
+
+const (
+	OpenPGPDefaultMD shared.MessageDigestAlgorithmId = 0
+)
+
+func NewCommandProcessor() *CommandProcessor {
+	cryptoSystems := make(map[shared.CryptoSystemId]*CryptoSystem)
+	cryptoSystems[CsX509] = &CryptoSystem{
+		Name: "X.509",
+		Roots: map[shared.CryptoSystemRootId]*RootCredentials{
+			X509RootDefault: {
+				Name:            "openssl",
+				PrivateKeyFile:  "/srv/ca/CA/private/ca.key.pem",
+				CertificateFile: "/srv/ca/CA/ca.crt.pem",
+				DatabaseFile:    "/srv/ca/CA/index.txt",
+				CRLNumber:       "/srv/ca/CA/crlnumber",
+			},
+			X509RootClass3: {
+				Name:            "class3",
+				PrivateKeyFile:  "/srv/ca/class3/private/ca.key.pem",
+				CertificateFile: "/srv/ca/class3/ca.crt.pem",
+				DatabaseFile:    "/srv/ca/class3/index.txt",
+				CRLNumber:       "/srv/ca/class3/crlnumber",
+			},
+			X509RootClass3s: {Name: "class3s"},
+			X509Root3:       {Name: "root3"},
+			X509Root4:       {Name: "root4"},
+			X509Root5:       {Name: "root5"},
+		},
+		Profiles: map[shared.CertificateProfileId]string{
+			X509ProfileClient:         "client",
+			X509ProfileClientOrg:      "client-org",
+			X509ProfileClientCodesign: "client-codesign",
+			X509ProfileClientMachine:  "client-machine",
+			X509ProfileClientAds:      "client-ads",
+			X509ProfileServer:         "server",
+			X509ProfileServerOrg:      "server-org",
+			X509ProfileServerJabber:   "server-jabber",
+			X509ProfileOCSP:           "ocsp",
+			X509ProfileTimestamp:      "timestamp",
+			X509ProfileProxy:          "proxy",
+			X509ProfileSubCA:          "subca",
+		},
+		// constants for openssl invocations. Should be replaced with
+		// something more useful
+		DigestAlgorithms: map[shared.MessageDigestAlgorithmId]x509.SignatureAlgorithm{
+			X509MDDefault:   x509.SHA256WithRSA,
+			X509MDMd5:       x509.MD5WithRSA,
+			X509MDSha1:      x509.SHA1WithRSA,
+			X509MDRipeMD160: x509.UnknownSignatureAlgorithm,
+			X509MDSha256:    x509.SHA256WithRSA,
+			X509MDSha384:    x509.SHA384WithRSA,
+			X509MDSha512:    x509.SHA512WithRSA,
+		},
+	}
+
+	cryptoSystems[CsOpenPGP] = &CryptoSystem{
+		Name: "OpenPGP",
+		Roots: map[shared.CryptoSystemRootId]*RootCredentials{
+			OpenPGPRoot0: {
+				Name:           "OpenPGP Root",
+				PrivateKeyFile: "secring0.gpg",
+				PublicKeyFile:  "pubring0.gpg",
+			},
+		},
+		Profiles: map[shared.CertificateProfileId]string{
+			OpenPGPDefaultProfile: "default",
+		},
+		// constants for gnupg cert-digest-algo parameter. Should be replaced with
+		// something more useful
+		DigestAlgorithms: map[shared.MessageDigestAlgorithmId]x509.SignatureAlgorithm{
+			OpenPGPDefaultMD: x509.SHA256WithRSA,
+		},
+	}
+
+	return &CommandProcessor{CryptoSystems: cryptoSystems, Settings: NewCommandProcessorSettings()}
+}