Initial work on attribute verification and issuance server/library

Co-authored-by: Confiks <confiks@scriptbase.org>

irmaserver/api.go

+package irmaserver
+
+import (
+	"github.com/Sirupsen/logrus"
+	"github.com/mhe/gabi"
+	"github.com/privacybydesign/irmago"
+)
+
+type Configuration struct {
+	IrmaConfigurationPath string
+
+	PrivateKeys       map[irma.IssuerIdentifier]*gabi.PrivateKey
+	IrmaConfiguration *irma.Configuration
+	Logger            *logrus.Logger
+}
+
+type SessionResult struct {
+	Token     string
+	Status    irma.ProofStatus
+	Disclosed []*irma.DisclosedAttribute
+	Signature *irma.SignedMessage
+	Err       *irma.RemoteError
+}
+
+type Status string
+
+const (
+	StatusInitialized Status = "INITIALIZED"
+	StatusConnected   Status = "CONNECTED"
+	StatusCancelled   Status = "CANCELLED"
+	StatusDone        Status = "DONE"
+)

irmaserver/backend/api.go

+package backend
+
+import (
+	"encoding/json"
+	"net/http"
+	"regexp"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/go-errors/errors"
+	"github.com/privacybydesign/irmago"
+	"github.com/privacybydesign/irmago/irmaserver"
+)
+
+func Initialize(configuration *irmaserver.Configuration) error {
+	conf = configuration
+
+	if conf.Logger == nil {
+		conf.Logger = logrus.New()
+		conf.Logger.Level = logrus.DebugLevel
+		conf.Logger.Formatter = &logrus.TextFormatter{}
+	}
+
+	if conf.IrmaConfiguration == nil {
+		var err error
+		conf.IrmaConfiguration, err = irma.NewConfiguration(conf.IrmaConfigurationPath, "")
+		if err != nil {
+			return err
+		}
+		if err = conf.IrmaConfiguration.ParseFolder(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func StartSession(request irma.SessionRequest) (*irma.Qr, string, error) {
+	if err := request.Validate(); err != nil {
+		return nil, "", err
+	}
+	action := irma.ActionUnknown
+	switch request.(type) {
+	case *irma.DisclosureRequest:
+		action = irma.ActionDisclosing
+	case *irma.SignatureRequest:
+		action = irma.ActionSigning
+	case *irma.IssuanceRequest:
+		action = irma.ActionIssuing
+		if err := validateIssuanceRequest(request.(*irma.IssuanceRequest)); err != nil {
+			return nil, "", err
+		}
+	default:
+		conf.Logger.Warnf("Attempt to start session of invalid type")
+		return nil, "", errors.New("Invalid session type")
+	}
+
+	session := newSession(action, request)
+	conf.Logger.Infof("%s session started, token %s", action, session.token)
+	return &irma.Qr{
+		Type: action,
+		URL:  session.token,
+	}, session.token, nil
+}
+
+func HandleProtocolMessage(
+	path string,
+	method string,
+	headers map[string][]string,
+	message []byte,
+) (status int, output []byte, result *irmaserver.SessionResult) {
+	// Parse path into session and action
+	if len(path) > 0 { // Remove any starting and trailing slash
+		if path[0] == '/' {
+			path = path[1:]
+		}
+		if path[len(path)-1] == '/' {
+			path = path[:len(path)-1]
+		}
+	}
+	conf.Logger.Debugf("Routing protocol message: %s %s", method, path)
+	pattern := regexp.MustCompile("(\\w+)/?(\\w*)")
+	matches := pattern.FindStringSubmatch(path)
+	if len(matches) != 3 {
+		conf.Logger.Warnf("Invalid URL: %s", path)
+		return failSession(nil, irmaserver.ErrorInvalidRequest, "")
+	}
+
+	token := matches[1]
+	verb := matches[2]
+	session := sessions.get(token)
+	if session == nil {
+		conf.Logger.Warnf("Session not found: %s", token)
+		return failSession(nil, irmaserver.ErrorSessionUnknown, "")
+	}
+
+	// Route to handler
+	switch len(verb) {
+	case 0:
+		if method == "DELETE" {
+			return handleDelete(session)
+		}
+		if method == "GET" {
+			h := http.Header(headers)
+			min := &irma.ProtocolVersion{}
+			max := &irma.ProtocolVersion{}
+			if err := json.Unmarshal([]byte(h.Get(irma.MinVersionHeader)), min); err != nil {
+				return failSession(session, irmaserver.ErrorMalformedInput, err.Error())
+			}
+			if err := json.Unmarshal([]byte(h.Get(irma.MaxVersionHeader)), max); err != nil {
+				return failSession(session, irmaserver.ErrorMalformedInput, err.Error())
+			}
+			return handleGetSession(session, min, max)
+		}
+		return failSession(session, irmaserver.ErrorInvalidRequest, "")
+	default:
+		if method == "POST" && (verb == "proofs" || (verb == "commitments" && session.action == irma.ActionIssuing)) {
+			return handlePostResponse(session, message)
+		}
+		if method == "GET" && verb == "status" {
+			return handleGetStatus(session)
+		}
+		return failSession(session, irmaserver.ErrorInvalidRequest, "")
+	}
+}

irmaserver/backend/handle.go

+package backend
+
+import (
+	"encoding/json"
+	"net/http"
+	"runtime/debug"
+
+	"github.com/mhe/gabi"
+	"github.com/privacybydesign/irmago"
+	"github.com/privacybydesign/irmago/irmaserver"
+)
+
+var conf *irmaserver.Configuration
+
+func handleDelete(session *session) (int, []byte, *irmaserver.SessionResult) {
+	var res *irmaserver.SessionResult
+	if session.alive() {
+		res = &irmaserver.SessionResult{Token: session.token} // TODO what to return here?
+	}
+	session.status = irmaserver.StatusCancelled
+	return http.StatusOK, nil, res
+}
+
+func handleGetSession(session *session, min, max *irma.ProtocolVersion) (int, []byte, *irmaserver.SessionResult) {
+	var err error
+	session.status = irmaserver.StatusConnected
+	if session.version, err = chooseProtocolVersion(min, max); err != nil {
+		return failSession(session, irmaserver.ErrorProtocolVersion, "")
+	}
+	session.request.SetVersion(session.version)
+	s, b := responseJson(session.request)
+	return s, b, nil
+}
+
+func handleGetStatus(session *session) (int, []byte, *irmaserver.SessionResult) {
+	b, _ := json.Marshal(session.status)
+	return http.StatusOK, b, nil
+}
+
+func handlePostResponse(session *session, message []byte) (int, []byte, *irmaserver.SessionResult) {
+	if !session.alive() {
+		return failSession(session, irmaserver.ErrorUnexpectedRequest, "")
+	}
+
+	switch session.action {
+
+	case irma.ActionSigning:
+		sig := &irma.SignedMessage{}
+		if err := irma.UnmarshalValidate(message, sig); err != nil {
+			return failSession(session, irmaserver.ErrorMalformedInput, "")
+		}
+		session.signature = sig
+		session.disclosed, session.proofStatus = sig.Verify(conf.IrmaConfiguration, session.request.(*irma.SignatureRequest))
+		s, b := responseJson(session.proofStatus)
+		return s, b, finishSession(session)
+
+	case irma.ActionDisclosing:
+		pl := gabi.ProofList{}
+		if err := irma.UnmarshalValidate(message, &pl); err != nil {
+			return failSession(session, irmaserver.ErrorMalformedInput, "")
+		}
+		session.disclosed, session.proofStatus = irma.ProofList(pl).Verify(conf.IrmaConfiguration, session.request.(*irma.DisclosureRequest))
+		s, b := responseJson(session.proofStatus)
+		return s, b, finishSession(session)
+
+	case irma.ActionIssuing:
+		commitments := &gabi.IssueCommitmentMessage{}
+		if err := irma.UnmarshalValidate(message, commitments); err != nil {
+			return failSession(session, irmaserver.ErrorMalformedInput, "")
+		}
+		return session.issue(commitments)
+
+	}
+
+	return failSession(session, irmaserver.ErrorUnknown, "")
+}
+
+func responseJson(v interface{}) (int, []byte) {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return http.StatusInternalServerError, nil // TODO
+	}
+	return http.StatusOK, b
+}
+
+func (session *session) alive() bool {
+	return session.status != irmaserver.StatusDone && session.status != irmaserver.StatusCancelled
+}
+
+func finishSession(session *session) *irmaserver.SessionResult {
+	session.status = irmaserver.StatusDone
+	return &irmaserver.SessionResult{
+		Token:     session.token,
+		Status:    session.proofStatus,
+		Disclosed: session.disclosed,
+		Signature: session.signature,
+	}
+}
+
+func failSession(session *session, err irmaserver.Error, message string) (int, []byte, *irmaserver.SessionResult) {
+	rerr := &irma.RemoteError{
+		Status:      err.Status,
+		Description: err.Description,
+		ErrorName:   string(err.Type),
+		Message:     message,
+		Stacktrace:  string(debug.Stack()),
+	}
+	conf.Logger.Errorf("Error: %d %s %s\n%s", rerr.Status, rerr.ErrorName, rerr.Message, rerr.Stacktrace)
+
+	var res *irmaserver.SessionResult
+	if session != nil {
+		if session.alive() {
+			res = &irmaserver.SessionResult{Err: rerr, Token: session.token}
+		}
+		session.status = irmaserver.StatusCancelled
+	}
+	b, _ := json.Marshal(rerr)
+	return err.Status, b, res
+}

irmaserver/backend/issue.go

+package backend
+
+import (
+	"fmt"
+	"strconv"
+	"time"
+
+	"github.com/dgrijalva/jwt-go"
+	"github.com/go-errors/errors"
+	"github.com/mhe/gabi"
+	"github.com/privacybydesign/irmago"
+	"github.com/privacybydesign/irmago/irmaserver"
+)
+
+func validateIssuanceRequest(request *irma.IssuanceRequest) error {
+	for _, cred := range request.Credentials {
+		// Check that we have the appropriate private key
+		iss := cred.CredentialTypeID.IssuerIdentifier()
+		privatekey, havekey := conf.PrivateKeys[iss]
+		if !havekey {
+			return fmt.Errorf("missing private key of issuer %s", iss.String())
+		}
+		pubkey, err := conf.IrmaConfiguration.PublicKey(iss, int(privatekey.Counter))
+		if err != nil {
+			return err
+		}
+		if pubkey == nil {
+			return fmt.Errorf("missing public key of issuer %s", iss.String())
+		}
+		cred.KeyCounter = int(privatekey.Counter)
+
+		// Check that the credential is consistent with irma_configuration
+		if err := cred.Validate(conf.IrmaConfiguration); err != nil {
+			return err
+		}
+
+		// Ensure the credential has an expiry date
+		defaultValidity := irma.Timestamp(time.Now().Add(6 * time.Hour))
+		if cred.Validity == nil {
+			cred.Validity = &defaultValidity
+		}
+		if cred.Validity.Before(irma.Timestamp(time.Now())) {
+			return errors.New("cannot issue expired credentials")
+		}
+	}
+
+	return nil
+}
+
+func (session *session) getProofP(commitments *gabi.IssueCommitmentMessage, scheme irma.SchemeManagerIdentifier) (*gabi.ProofP, error) {
+	if session.kssProofs == nil {
+		session.kssProofs = make(map[irma.SchemeManagerIdentifier]*gabi.ProofP)
+	}
+
+	if _, contains := session.kssProofs[scheme]; !contains {
+		str, contains := commitments.ProofPjwts[scheme.Name()]
+		if !contains {
+			return nil, errors.Errorf("no keyshare proof included for scheme %s", scheme.Name())
+		}
+		claims := &struct {
+			jwt.StandardClaims
+			ProofP *gabi.ProofP
+		}{}
+		token, err := jwt.ParseWithClaims(str, claims, func(t *jwt.Token) (interface{}, error) {
+			var kid int
+			if kidstr, ok := t.Header["kid"].(string); ok {
+				var err error
+				if kid, err = strconv.Atoi(kidstr); err != nil {
+					return nil, err
+				}
+			}
+			return conf.IrmaConfiguration.KeyshareServerPublicKey(scheme, kid)
+		})
+		if err != nil {
+			return nil, err
+		}
+		if !token.Valid {
+			return nil, errors.Errorf("invalid keyshare proof included for scheme %s", scheme.Name())
+		}
+		session.kssProofs[scheme] = claims.ProofP
+	}
+
+	return session.kssProofs[scheme], nil
+}
+
+func (session *session) issue(commitments *gabi.IssueCommitmentMessage) (int, []byte, *irmaserver.SessionResult) {
+	request := session.request.(*irma.IssuanceRequest)
+	discloseCount := len(request.Disclose)
+	if len(commitments.Proofs) != len(request.Credentials)+discloseCount {
+		return failSession(session, irmaserver.ErrorAttributesMissing, "")
+	}
+
+	// Compute list of public keys against which to verify the received proofs
+	disclosureproofs := irma.ProofList(commitments.Proofs[:discloseCount])
+	pubkeys, err := disclosureproofs.ExtractPublicKeys(conf.IrmaConfiguration)
+	if err != nil {
+		return failSession(session, irmaserver.ErrorInvalidProofs, err.Error())
+	}
+	for _, cred := range request.Credentials {
+		iss := cred.CredentialTypeID.IssuerIdentifier()
+		pubkey, _ := conf.IrmaConfiguration.PublicKey(iss, cred.KeyCounter) // No error, already checked earlier
+		pubkeys = append(pubkeys, pubkey)
+	}
+
+	// Verify and merge keyshare server proofs, if any
+	for i, proof := range commitments.Proofs {
+		pubkey := pubkeys[i]
+		schemeid := irma.NewIssuerIdentifier(pubkey.Issuer).SchemeManagerIdentifier()
+		if conf.IrmaConfiguration.SchemeManagers[schemeid].Distributed() {
+			proofP, err := session.getProofP(commitments, schemeid)
+			if err != nil {
+				failSession(session, irmaserver.ErrorKeyshareProofMissing, err.Error())
+			}
+			proof.MergeProofP(proofP, pubkey)
+		}
+	}
+
+	// Verify all proofs and check disclosed attributes, if any, against request
+	session.disclosed, session.proofStatus = irma.ProofList(commitments.Proofs).VerifyAgainstDisjunctions(
+		conf.IrmaConfiguration, request.Disclose, request.Context, request.Nonce, pubkeys, false)
+	if session.proofStatus != irma.ProofStatusValid {
+		return failSession(session, irmaserver.ErrorInvalidProofs, "")
+	}
+
+	// Compute CL signatures
+	var sigs []*gabi.IssueSignatureMessage
+	for i, cred := range request.Credentials {
+		id := cred.CredentialTypeID.IssuerIdentifier()
+		pk, _ := conf.IrmaConfiguration.PublicKey(id, cred.KeyCounter)
+		issuer := gabi.NewIssuer(conf.PrivateKeys[id], pk, one)
+		proof := commitments.Proofs[i+discloseCount].(*gabi.ProofU)
+		attributes, err := cred.AttributeList(conf.IrmaConfiguration, 0x03)
+		if err != nil {
+			return failSession(session, irmaserver.ErrorUnknown, err.Error())
+		}
+		sig, err := issuer.IssueSignature(proof.U, attributes.Ints, commitments.Nonce2)
+		if err != nil {
+			return failSession(session, irmaserver.ErrorUnknown, err.Error())
+		}
+		sigs = append(sigs, sig)
+	}
+
+	s, b := responseJson(sigs)
+	return s, b, finishSession(session)
+}

irmaserver/backend/sessions.go

+package backend
+
+import (
+	"math/big"
+	"math/rand"
+	"sync"
+
+	"github.com/go-errors/errors"
+	"github.com/mhe/gabi"
+	"github.com/privacybydesign/irmago"
+	"github.com/privacybydesign/irmago/irmaserver"
+)
+
+type session struct {
+	action  irma.Action
+	token   string
+	version *irma.ProtocolVersion
+	request irma.SessionRequest
+	status  irmaserver.Status
+
+	proofStatus irma.ProofStatus
+	disclosed   []*irma.DisclosedAttribute
+	signature   *irma.SignedMessage
+
+	kssProofs map[irma.SchemeManagerIdentifier]*gabi.ProofP
+}
+
+type sessionStore interface {
+	get(token string) *session
+	add(token string, session *session)
+}
+
+type memorySessionStore struct {
+	sync.RWMutex
+	m map[string]*session
+}
+
+const sessionChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+
+var (
+	minProtocolVersion = irma.NewVersion(2, 4)
+	maxProtocolVersion = irma.NewVersion(2, 4)
+
+	sessions sessionStore = &memorySessionStore{
+		m: make(map[string]*session),
+	}
+)
+
+func (s *memorySessionStore) get(token string) *session {
+	s.RLock()
+	defer s.RUnlock()
+	return s.m[token]
+}
+
+func (s *memorySessionStore) add(token string, session *session) {
+	s.Lock()
+	defer s.Unlock()
+	s.m[token] = session
+}
+
+var one *big.Int = big.NewInt(1)
+
+func newSession(action irma.Action, request irma.SessionRequest) *session {
+	s := &session{
+		action:  action,
+		request: request,
+		status:  irmaserver.StatusInitialized,
+		token:   newSessionToken(),
+	}
+	nonce, _ := gabi.RandomBigInt(gabi.DefaultSystemParameters[2048].Lstatzk)
+	request.SetNonce(nonce)
+	request.SetContext(one)
+	sessions.add(s.token, s)
+	return s
+}
+
+func newSessionToken() string {
+	b := make([]byte, 20)
+	for i := range b {
+		b[i] = sessionChars[rand.Int63()%int64(len(sessionChars))]
+	}
+	return string(b)
+}
+
+func chooseProtocolVersion(min, max *irma.ProtocolVersion) (*irma.ProtocolVersion, error) {
+	if min.AboveVersion(minProtocolVersion) || max.BelowVersion(min) {
+		return nil, errors.Errorf("Protocol version negotiation failed, min=%s max=%s", min.String(), max.String())
+	}
+	if max.AboveVersion(maxProtocolVersion) {
+		return maxProtocolVersion, nil
+	} else {
+		return max, nil
+	}
+}

irmaserver/errors.go

+package irmaserver
+
+type Error struct {
+	Type        ErrorType `json:"error"`
+	Status      int       `json:"status"`
+	Description string    `json:"description"`
+}
+
+type ErrorType string
+
+var (
+	ErrorMalformedIssuerRequest    Error = Error{Type: "MALFORMED_ISSUER_REQUEST", Status: 400, Description: "Malformed issuer request"}
+	ErrorInvalidTimestamp          Error = Error{Type: "INVALID_TIMESTAMP", Status: 400, Description: "Timestamp was not an epoch boundary"}
+	ErrorIssuingDisabled           Error = Error{Type: "ISSUING_DISABLED", Status: 403, Description: "This server does not support issuing"}
+	ErrorMalformedVerifierRequest  Error = Error{Type: "MALFORMED_VERIFIER_REQUEST", Status: 400, Description: "Malformed verification request"}
+	ErrorMalformedSignatureRequest Error = Error{Type: "MALFORMED_SIGNATURE_REQUEST", Status: 400, Description: "Malformed signature request"}
+	ErrorInvalidProofs             Error = Error{Type: "INVALID_PROOFS", Status: 400, Description: "Invalid secret key commitments and/or disclosure proofs"}
+	ErrorAttributesMissing         Error = Error{Type: "ATTRIBUTES_MISSING", Status: 400, Description: "Not all requested-for attributes were present"}
+	ErrorAttributesExpired         Error = Error{Type: "ATTRIBUTES_EXPIRED", Status: 400, Description: "Disclosed attributes were expired"}
+	ErrorUnexpectedRequest         Error = Error{Type: "UNEXPECTED_REQUEST", Status: 403, Description: "Unexpected request in this state"}
+	ErrorUnknownPublicKey          Error = Error{Type: "UNKNOWN_PUBLIC_KEY", Status: 403, Description: "Attributes were not valid against a known public key"}
+	ErrorKeyshareProofMissing      Error = Error{Type: "KEYSHARE_PROOF_MISSING", Status: 403, Description: "ProofP object from a keyshare server missing"}
+	ErrorUnauthorized              Error = Error{Type: "UNAUTHORIZED", Status: 403, Description: "You are not authorized to issue or verify this attribute"}
+	ErrorAttributesWrong           Error = Error{Type: "ATTRIBUTES_WRONG", Status: 400, Description: "Specified attribute(s) do not belong to this credential type or missing attributes"}
+	ErrorSessionUnknown            Error = Error{Type: "SESSION_UNKNOWN", Status: 400, Description: "Unknown or expired session"}
+	ErrorSessionTokenMalformed     Error = Error{Type: "SESSION_TOKEN_MALFORMED", Status: 400, Description: "Malformed session token"}
+	ErrorMalformedInput            Error = Error{Type: "MALFORMED_INPUT", Status: 400, Description: "Input could not be parsed"}
+	ErrorCannotIssue               Error = Error{Type: "CANNOT_ISSUE", Status: 500, Description: "Cannot issue this credential"}
+	ErrorIssuanceFailed            Error = Error{Type: "ISSUANCE_FAILED", Status: 500, Description: "Failed to create credential(s)"}
+	ErrorUnknown                   Error = Error{Type: "EXCEPTION", Status: 500, Description: "Encountered unexpected problem"}
+
+	ErrorInvalidRequest  Error = Error{Type: "INVALID_REQUEST", Status: 400, Description: "Invalid HTTP request"}
+	ErrorProtocolVersion Error = Error{Type: "PROTOCOL_VERSION", Status: 400, Description: "Protocol version negotiation failed"}
+)

irmaserver/irmarequestor/main.go

+package irmarequestor
+
+import (
+	"io/ioutil"
+	"net/http"
+	"sync"
+
+	"github.com/privacybydesign/irmago"
+	"github.com/privacybydesign/irmago/irmaserver"
+	"github.com/privacybydesign/irmago/irmaserver/backend"
+)
+
+type SessionHandler func(*irmaserver.SessionResult)
+
+type SessionStore interface {
+	Get(token string) *irmaserver.SessionResult
+	Add(token string, result *irmaserver.SessionResult)
+	GetHandler(token string) SessionHandler
+	SetHandler(token string, handler SessionHandler)
+	SupportHandlers() bool
+}
+
+var Sessions SessionStore = &MemorySessionStore{
+	m: make(map[string]*irmaserver.SessionResult),
+	h: make(map[string]SessionHandler),
+}
+
+type MemorySessionStore struct {
+	sync.RWMutex
+	m map[string]*irmaserver.SessionResult
+	h map[string]SessionHandler
+}
+
+func Initialize(configuration *irmaserver.Configuration) error {
+	return backend.Initialize(configuration)
+}
+
+func StartSession(request irma.SessionRequest, handler SessionHandler) (*irma.Qr, string, error) {
+	if handler != nil && !Sessions.SupportHandlers() {
+		panic("Handlers not supported")
+	}
+	qr, token, err := backend.StartSession(request)
+	if err != nil {
+		return nil, "", err
+	}
+	if handler != nil {