irmaconfig.go 31.1 KB
Newer Older
1
package irma
2
3
4
5
6
7
8

import (
	"encoding/base64"
	"encoding/xml"
	"io/ioutil"
	"os"
	"path/filepath"
9
	"regexp"
10
11
	"strconv"

12
13
	"crypto/sha256"

14
15
16
17
	"fmt"

	"strings"

18
19
20
21
22
23
24
25
26
27
28
29
	"sort"

	"bytes"

	"encoding/hex"

	"crypto/ecdsa"
	"crypto/x509"
	"encoding/asn1"
	"encoding/pem"
	"math/big"

30
	"github.com/go-errors/errors"
31
	"github.com/mhe/gabi"
32
	"github.com/privacybydesign/irmago/internal/fs"
33
34
)

35
// Configuration keeps track of scheme managers, issuers, credential types and public keys,
36
// dezerializing them from an irma_configuration folder, and downloads and saves new ones on demand.
37
type Configuration struct {
38
39
40
	SchemeManagers  map[SchemeManagerIdentifier]*SchemeManager
	Issuers         map[IssuerIdentifier]*Issuer
	CredentialTypes map[CredentialTypeIdentifier]*CredentialType
41

Sietse Ringers's avatar
Sietse Ringers committed
42
43
44
	// Path to the irma_configuration folder that this instance represents
	Path string

45
46
47
	// DisabledSchemeManagers keeps track of scheme managers that did not parse  succesfully
	// (i.e., invalid signature, parsing error), and the problem that occurred when parsing them
	DisabledSchemeManagers map[SchemeManagerIdentifier]*SchemeManagerError
48

49
50
	Warnings []string

51
	publicKeys    map[IssuerIdentifier]map[int]*gabi.PublicKey
52
	reverseHashes map[string]CredentialTypeIdentifier
53
	initialized   bool
54
	assets        string
55
56
}

Sietse Ringers's avatar
Sietse Ringers committed
57
58
// ConfigurationFileHash encodes the SHA256 hash of an authenticated
// file under a scheme manager within the configuration folder.
59
60
type ConfigurationFileHash []byte

Sietse Ringers's avatar
Sietse Ringers committed
61
62
// SchemeManagerIndex is a (signed) list of files under a scheme manager
// along with their SHA266 hash
63
64
type SchemeManagerIndex map[string]ConfigurationFileHash

65
66
type SchemeManagerStatus string

67
68
type SchemeManagerError struct {
	Manager SchemeManagerIdentifier
69
	Status  SchemeManagerStatus
70
71
72
	Err     error
}

73
74
75
76
77
78
79
const (
	SchemeManagerStatusValid               = SchemeManagerStatus("Valid")
	SchemeManagerStatusUnprocessed         = SchemeManagerStatus("Unprocessed")
	SchemeManagerStatusInvalidIndex        = SchemeManagerStatus("InvalidIndex")
	SchemeManagerStatusInvalidSignature    = SchemeManagerStatus("InvalidSignature")
	SchemeManagerStatusParsingError        = SchemeManagerStatus("ParsingError")
	SchemeManagerStatusContentParsingError = SchemeManagerStatus("ContentParsingError")
80
81

	pubkeyPattern = "%s/%s/%s/PublicKeys/*.xml"
82
83
)

84
85
86
87
func (sme SchemeManagerError) Error() string {
	return fmt.Sprintf("Error parsing scheme manager %s: %s", sme.Manager.Name(), sme.Err.Error())
}

88
// NewConfiguration returns a new configuration. After this
89
// ParseFolder() should be called to parse the specified path.
90
91
func NewConfiguration(path string, assets string) (conf *Configuration, err error) {
	conf = &Configuration{
Sietse Ringers's avatar
Sietse Ringers committed
92
		Path:   path,
93
		assets: assets,
94
	}
95

96
97
98
99
	if conf.assets != "" { // If an assets folder is specified, then it must exist
		if err = fs.AssertPathExists(conf.assets); err != nil {
			return nil, errors.WrapPrefix(err, "Nonexistent assets folder specified", 0)
		}
100
	}
101
	if err = fs.EnsureDirectoryExists(conf.Path); err != nil {
102
103
		return nil, err
	}
104

105
106
107
	// Init all maps
	conf.clear()

108
109
110
	return
}

111
func (conf *Configuration) clear() {
112
113
114
	conf.SchemeManagers = make(map[SchemeManagerIdentifier]*SchemeManager)
	conf.Issuers = make(map[IssuerIdentifier]*Issuer)
	conf.CredentialTypes = make(map[CredentialTypeIdentifier]*CredentialType)
115
	conf.DisabledSchemeManagers = make(map[SchemeManagerIdentifier]*SchemeManagerError)
116
	conf.publicKeys = make(map[IssuerIdentifier]map[int]*gabi.PublicKey)
117
	conf.reverseHashes = make(map[string]CredentialTypeIdentifier)
118
119
120
121
122
123
124
}

// ParseFolder populates the current Configuration by parsing the storage path,
// listing the containing scheme managers, issuers and credential types.
func (conf *Configuration) ParseFolder() (err error) {
	// Init all maps
	conf.clear()
125

126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
	// Copy any new or updated scheme managers out of the assets into storage
	if conf.assets != "" {
		err = iterateSubfolders(conf.assets, func(dir string) error {
			scheme := NewSchemeManagerIdentifier(filepath.Base(dir))
			uptodate, err := conf.isUpToDate(scheme)
			if err != nil {
				return err
			}
			if !uptodate {
				_, err = conf.CopyManagerFromAssets(scheme)
			}
			return err
		})
		if err != nil {
			return err
		}
	}

	// Parse scheme managers in storage
145
	var mgrerr *SchemeManagerError
Sietse Ringers's avatar
Sietse Ringers committed
146
	err = iterateSubfolders(conf.Path, func(dir string) error {
147
148
		manager := NewSchemeManager(filepath.Base(dir))
		err := conf.ParseSchemeManagerFolder(dir, manager)
149
150
		if err == nil {
			return nil // OK, do next scheme manager folder
151
		}
152
153
154
155
		// If there is an error, and it is of type SchemeManagerError, return nil
		// so as to continue parsing other managers.
		var ok bool
		if mgrerr, ok = err.(*SchemeManagerError); ok {
156
			conf.DisabledSchemeManagers[manager.Identifier()] = mgrerr
157
			return nil
158
		}
159
		return err // Not a SchemeManagerError? return it & halt parsing now
160
161
	})
	if err != nil {
162
		return
163
	}
164
	conf.initialized = true
165
166
167
	if mgrerr != nil {
		return mgrerr
	}
168
	return
169
170
}

171
172
173
174
175
176
177
// ParseOrRestoreFolder parses the irma_configuration folder, and when possible attempts to restore
// any broken scheme managers from their remote.
// Any error encountered during parsing is considered recoverable only if it is of type *SchemeManagerError;
// In this case the scheme in which it occured is downloaded from its remote and re-parsed.
// If any other error is encountered at any time, it is returned immediately.
// If no error is returned, parsing and possibly restoring has been succesfull, and there should be no
// disabled scheme managers.
178
179
func (conf *Configuration) ParseOrRestoreFolder() error {
	err := conf.ParseFolder()
180
181
182
	// Only in case of a *SchemeManagerError might we be able to recover
	if _, isSchemeMgrErr := err.(*SchemeManagerError); !isSchemeMgrErr {
		return err
183
	}
184
185

	for id := range conf.DisabledSchemeManagers {
186
187
188
189
190
191
192
193
194
		if err = conf.ReinstallSchemeManager(conf.SchemeManagers[id]); err == nil {
			continue
		}
		if _, err = conf.CopyManagerFromAssets(id); err != nil {
			return err // File system error, too serious, bail out now
		}
		name := id.String()
		if err = conf.ParseSchemeManagerFolder(filepath.Join(conf.Path, name), NewSchemeManager(name)); err == nil {
			delete(conf.DisabledSchemeManagers, id)
195
		}
196
	}
197

198
199
200
	return err
}

201
// ParseSchemeManagerFolder parses the entire tree of the specified scheme manager
202
// If err != nil then a problem occured
203
func (conf *Configuration) ParseSchemeManagerFolder(dir string, manager *SchemeManager) (err error) {
204
205
206
207
208
209
210
	// From this point, keep it in our map even if it has an error. The user must check either:
	// - manager.Status == SchemeManagerStatusValid, aka "VALID"
	// - or equivalently, manager.Valid == true
	// before using any scheme manager for anything, and handle accordingly
	conf.SchemeManagers[manager.Identifier()] = manager

	// Ensure we return a SchemeManagerError when any error occurs
211
212
	defer func() {
		if err != nil {
213
214
215
216
217
			err = &SchemeManagerError{
				Manager: manager.Identifier(),
				Err:     err,
				Status:  manager.Status,
			}
218
219
220
		}
	}()

221
222
	// Verify signature and read scheme manager description
	if err = conf.VerifySignature(manager.Identifier()); err != nil {
223
224
		return
	}
225
	if manager.index, err = conf.parseIndex(filepath.Base(dir), manager); err != nil {
226
227
		manager.Status = SchemeManagerStatusInvalidIndex
		return
228
	}
229
230
231
232
233
	exists, err := conf.pathToDescription(manager, dir+"/description.xml", manager)
	if !exists {
		manager.Status = SchemeManagerStatusParsingError
		return errors.New("Scheme manager description not found")
	}
234
235
236
	if err != nil {
		manager.Status = SchemeManagerStatusParsingError
		return
237
	}
238
239
240
241
	if manager.XMLVersion < 7 {
		manager.Status = SchemeManagerStatusParsingError
		return errors.New("Unsupported scheme manager description")
	}
242
243
244
	if filepath.Base(dir) != manager.ID {
		return errors.Errorf("Scheme %s has wrong directory name %s", manager.ID, filepath.Base(dir))
	}
245
246
247
248
249
250
251

	// Verify that all other files are validly signed
	err = conf.VerifySchemeManager(manager)
	if err != nil {
		manager.Status = SchemeManagerStatusInvalidSignature
		return
	}
252

253
	// Read timestamp indicating time of last modification
254
255
256
	ts, exists, err := readTimestamp(dir + "/timestamp")
	if err != nil || !exists {
		return errors.WrapPrefix(err, "Could not read scheme manager timestamp", 0)
257
	}
258
	manager.Timestamp = *ts
259

260
	// Parse contained issuers and credential types
261
	err = conf.parseIssuerFolders(manager, dir)
262
263
264
265
266
267
	if err != nil {
		manager.Status = SchemeManagerStatusContentParsingError
		return
	}
	manager.Status = SchemeManagerStatusValid
	manager.Valid = true
268
269
270
	return
}

271
272
273
274
func relativePath(absolute string, relative string) string {
	return relative[len(absolute)+1:]
}

275
276
277
278
// PublicKey returns the specified public key, or nil if not present in the Configuration.
func (conf *Configuration) PublicKey(id IssuerIdentifier, counter int) (*gabi.PublicKey, error) {
	if _, contains := conf.publicKeys[id]; !contains {
		conf.publicKeys[id] = map[int]*gabi.PublicKey{}
279
		if err := conf.parseKeysFolder(conf.SchemeManagers[id.SchemeManagerIdentifier()], id); err != nil {
280
			return nil, err
281
282
		}
	}
283
	return conf.publicKeys[id][counter], nil
284
285
}

286
func (conf *Configuration) addReverseHash(credid CredentialTypeIdentifier) {
287
	hash := sha256.Sum256([]byte(credid.String()))
288
	conf.reverseHashes[base64.StdEncoding.EncodeToString(hash[:16])] = credid
289
290
}

291
292
293
func (conf *Configuration) hashToCredentialType(hash []byte) *CredentialType {
	if str, exists := conf.reverseHashes[base64.StdEncoding.EncodeToString(hash)]; exists {
		return conf.CredentialTypes[str]
294
295
296
297
	}
	return nil
}

298
// IsInitialized indicates whether this instance has successfully been initialized.
299
300
func (conf *Configuration) IsInitialized() bool {
	return conf.initialized
301
302
}

303
304
305
306
307
308
309
310
311
// Prune removes any invalid scheme managers and everything they own from this Configuration
func (conf *Configuration) Prune() {
	for _, manager := range conf.SchemeManagers {
		if !manager.Valid {
			_ = conf.RemoveSchemeManager(manager.Identifier(), false) // does not return errors
		}
	}
}

312
func (conf *Configuration) parseIssuerFolders(manager *SchemeManager, path string) error {
313
314
	return iterateSubfolders(path, func(dir string) error {
		issuer := &Issuer{}
315
		exists, err := conf.pathToDescription(manager, dir+"/description.xml", issuer)
316
317
318
		if err != nil {
			return err
		}
319
320
		if !exists {
			return nil
321
		}
322
323
324
		if issuer.XMLVersion < 4 {
			return errors.New("Unsupported issuer description")
		}
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
		issuerid := issuer.Identifier()

		// Check that the issuer has public keys
		pkpath := fmt.Sprintf(pubkeyPattern, conf.Path, issuerid.SchemeManagerIdentifier().Name(), issuerid.Name())
		files, err := filepath.Glob(pkpath)
		if err != nil {
			return err
		}
		if len(files) == 0 {
			conf.Warnings = append(conf.Warnings, fmt.Sprintf("Issuer %s has no public keys", issuerid.String()))
		}

		if filepath.Base(dir) != issuer.ID {
			return errors.Errorf("Issuer %s has wrong directory name %s", issuerid.String(), filepath.Base(dir))
		}
		if manager.ID != issuer.SchemeManagerID {
			return errors.Errorf("Issuer %s has wrong SchemeManager %s", issuerid.String(), issuer.SchemeManagerID)
		}
		if err = fs.AssertPathExists(dir + "/logo.png"); err != nil {
			conf.Warnings = append(conf.Warnings, fmt.Sprintf("Issuer %s has no logo.png", issuerid.String()))
		}

		conf.Issuers[issuerid] = issuer
348
		issuer.Valid = conf.SchemeManagers[issuer.SchemeManagerIdentifier()].Valid
349
		return conf.parseCredentialsFolder(manager, issuer, dir+"/Issues/")
350
351
352
	})
}

353
354
355
func (conf *Configuration) DeleteSchemeManager(id SchemeManagerIdentifier) error {
	delete(conf.SchemeManagers, id)
	delete(conf.DisabledSchemeManagers, id)
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
	name := id.String()
	for iss := range conf.Issuers {
		if iss.Root() == name {
			delete(conf.Issuers, iss)
		}
	}
	for iss := range conf.publicKeys {
		if iss.Root() == name {
			delete(conf.publicKeys, iss)
		}
	}
	for cred := range conf.CredentialTypes {
		if cred.Root() == name {
			delete(conf.CredentialTypes, cred)
		}
	}
372
373
374
	return os.RemoveAll(filepath.Join(conf.Path, id.Name()))
}

375
// parse $schememanager/$issuer/PublicKeys/$i.xml for $i = 1, ...
376
func (conf *Configuration) parseKeysFolder(manager *SchemeManager, issuerid IssuerIdentifier) error {
377
	path := fmt.Sprintf(pubkeyPattern, conf.Path, issuerid.SchemeManagerIdentifier().Name(), issuerid.Name())
378
379
380
381
382
383
384
385
386
387
388
	files, err := filepath.Glob(path)
	if err != nil {
		return err
	}

	for _, file := range files {
		filename := filepath.Base(file)
		count := filename[:len(filename)-4]
		i, err := strconv.Atoi(count)
		if err != nil {
			continue
389
		}
Sietse Ringers's avatar
Sietse Ringers committed
390
		bts, found, err := conf.ReadAuthenticatedFile(manager, relativePath(conf.Path, file))
391
		if err != nil || !found {
392
393
394
			return err
		}
		pk, err := gabi.NewPublicKeyFromBytes(bts)
395
396
397
		if err != nil {
			return err
		}
398
		pk.Issuer = issuerid.String()
399
		conf.publicKeys[issuerid][i] = pk
400
	}
401

402
403
404
	return nil
}

405
// parse $schememanager/$issuer/Issues/*/description.xml
406
407
408
func (conf *Configuration) parseCredentialsFolder(manager *SchemeManager, issuer *Issuer, path string) error {
	var foundcred bool
	err := iterateSubfolders(path, func(dir string) error {
409
		cred := &CredentialType{}
410
		exists, err := conf.pathToDescription(manager, dir+"/description.xml", cred)
411
412
413
		if err != nil {
			return err
		}
414
415
416
417
418
		if !exists {
			return nil
		}
		if cred.XMLVersion < 4 {
			return errors.New("Unsupported credential type description")
419
		}
420
		credid := cred.Identifier()
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
		if cred.ID != filepath.Base(dir) {
			return errors.Errorf("Credential type %s has wrong directory name %s", credid.String(), filepath.Base(dir))
		}
		if cred.IssuerID != issuer.ID {
			return errors.Errorf("Credential type %s has wrong IssuerID %s", credid.String(), cred.IssuerID)
		}
		if cred.SchemeManagerID != manager.ID {
			return errors.Errorf("Credential type %s has wrong SchemeManager %s", credid.String(), cred.SchemeManagerID)
		}
		if err = fs.AssertPathExists(dir + "/logo.png"); err != nil {
			conf.Warnings = append(conf.Warnings, fmt.Sprintf("Credential type %s has no logo.png", credid.String()))
		}
		if err = conf.checkAttributes(cred); err != nil {
			return err
		}

		foundcred = true
		cred.Valid = conf.SchemeManagers[cred.SchemeManagerIdentifier()].Valid

440
441
		conf.CredentialTypes[credid] = cred
		conf.addReverseHash(credid)
442
443
		return nil
	})
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
	if !foundcred {
		conf.Warnings = append(conf.Warnings, fmt.Sprintf("Issuer %s has no credential types", issuer.Identifier().String()))
	}
	return err
}

func (conf *Configuration) checkAttributes(cred *CredentialType) error {
	name := cred.Identifier().String()
	indices := make(map[int]struct{})
	count := len(cred.Attributes)
	if count == 0 {
		return errors.Errorf("Credenial type %s has no attributes", name)
	}
	for i, attr := range cred.Attributes {
		index := i
		if attr.Index != nil {
			index = *attr.Index
		}
		if index >= count {
			conf.Warnings = append(conf.Warnings, fmt.Sprintf("Credential type %s has invalid attribute index at attribute %d", name, i))
		}
		indices[index] = struct{}{}
	}
	if len(indices) != count {
		conf.Warnings = append(conf.Warnings, fmt.Sprintf("Credential type %s has invalid attribute ordering, check the index-tags", name))
	}
	return nil
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
}

// iterateSubfolders iterates over the subfolders of the specified path,
// calling the specified handler each time. If anything goes wrong, or
// if the caller returns a non-nil error, an error is immediately returned.
func iterateSubfolders(path string, handler func(string) error) error {
	dirs, err := filepath.Glob(path + "/*")
	if err != nil {
		return err
	}

	for _, dir := range dirs {
		stat, err := os.Stat(dir)
		if err != nil {
			return err
		}
		if !stat.IsDir() {
			continue
		}
490
491
492
		if strings.HasSuffix(dir, "/.git") {
			continue
		}
493
494
495
496
497
498
499
500
501
		err = handler(dir)
		if err != nil {
			return err
		}
	}

	return nil
}

502
func (conf *Configuration) pathToDescription(manager *SchemeManager, path string, description interface{}) (bool, error) {
503
504
505
506
	if _, err := os.Stat(path); err != nil {
		return false, nil
	}

Sietse Ringers's avatar
Sietse Ringers committed
507
	bts, found, err := conf.ReadAuthenticatedFile(manager, relativePath(conf.Path, path))
508
509
510
	if !found {
		return false, nil
	}
511
512
513
514
	if err != nil {
		return true, err
	}

515
	err = xml.Unmarshal(bts, description)
516
517
518
519
520
521
	if err != nil {
		return true, err
	}

	return true, nil
}
522

523
524
525
526
527
// Contains checks if the configuration contains the specified credential type.
func (conf *Configuration) Contains(cred CredentialTypeIdentifier) bool {
	return conf.SchemeManagers[cred.IssuerIdentifier().SchemeManagerIdentifier()] != nil &&
		conf.Issuers[cred.IssuerIdentifier()] != nil &&
		conf.CredentialTypes[cred] != nil
528
}
529

530
func (conf *Configuration) isUpToDate(scheme SchemeManagerIdentifier) (bool, error) {
531
532
533
	if conf.assets == "" {
		return true, nil
	}
534
535
536
537
	name := scheme.String()
	newTime, exists, err := readTimestamp(filepath.Join(conf.assets, name, "timestamp"))
	if err != nil || !exists {
		return true, errors.WrapPrefix(err, "Could not read asset timestamp of scheme "+name, 0)
538
	}
539
540
541
542
	// The storage version of the manager does not need to have a timestamp. If it does not, it is outdated.
	oldTime, exists, err := readTimestamp(filepath.Join(conf.Path, name, "timestamp"))
	if err != nil {
		return true, err
543
	}
544
	return exists && !newTime.After(*oldTime), nil
545
546
}

547
func (conf *Configuration) CopyManagerFromAssets(scheme SchemeManagerIdentifier) (bool, error) {
548
	if conf.assets == "" {
549
		return false, nil
550
	}
551
552
553
554
555
	// Remove old version; we want an exact copy of the assets version
	// not a merge of the assets version and the storage version
	name := scheme.String()
	if err := os.RemoveAll(filepath.Join(conf.Path, name)); err != nil {
		return false, err
556
	}
557
558
559
	return true, fs.CopyDirectory(
		filepath.Join(conf.assets, name),
		filepath.Join(conf.Path, name),
560
561
562
	)
}

563
564
// DownloadSchemeManager downloads and returns a scheme manager description.xml file
// from the specified URL.
565
func DownloadSchemeManager(url string) (*SchemeManager, error) {
566
567
568
569
570
571
572
573
574
	if !strings.HasPrefix(url, "http://") && !strings.HasPrefix(url, "https://") {
		url = "https://" + url
	}
	if url[len(url)-1] == '/' {
		url = url[:len(url)-1]
	}
	if strings.HasSuffix(url, "/description.xml") {
		url = url[:len(url)-len("/description.xml")]
	}
575
	b, err := NewHTTPTransport(url).GetBytes("description.xml")
576
577
578
	if err != nil {
		return nil, err
	}
579
	manager := NewSchemeManager("")
580
581
582
583
584
585
586
587
	if err = xml.Unmarshal(b, manager); err != nil {
		return nil, err
	}

	manager.URL = url // TODO?
	return manager, nil
}

Sietse Ringers's avatar
Sietse Ringers committed
588
589
// RemoveSchemeManager removes the specified scheme manager and all associated issuers,
// public keys and credential types from this Configuration.
590
func (conf *Configuration) RemoveSchemeManager(id SchemeManagerIdentifier, fromStorage bool) error {
591
	// Remove everything falling under the manager's responsibility
592
	for credid := range conf.CredentialTypes {
593
		if credid.IssuerIdentifier().SchemeManagerIdentifier() == id {
594
			delete(conf.CredentialTypes, credid)
595
596
		}
	}
597
	for issid := range conf.Issuers {
598
		if issid.SchemeManagerIdentifier() == id {
599
			delete(conf.Issuers, issid)
600
601
		}
	}
602
	for issid := range conf.publicKeys {
603
		if issid.SchemeManagerIdentifier() == id {
604
			delete(conf.publicKeys, issid)
605
606
		}
	}
607
	delete(conf.SchemeManagers, id)
608
609

	if fromStorage {
Sietse Ringers's avatar
Sietse Ringers committed
610
		return os.RemoveAll(fmt.Sprintf("%s/%s", conf.Path, id.String()))
611
612
	}
	return nil
613
614
}

615
616
617
618
619
620
621
622
623
624
625
626
627
628
func (conf *Configuration) ReinstallSchemeManager(manager *SchemeManager) (err error) {
	// Check if downloading stuff from the remote works before we uninstall the specified manager:
	// If we can't download anything we should keep the broken version
	manager, err = DownloadSchemeManager(manager.URL)
	if err != nil {
		return
	}
	if err = conf.DeleteSchemeManager(manager.Identifier()); err != nil {
		return
	}
	err = conf.InstallSchemeManager(manager)
	return
}

629
// InstallSchemeManager downloads and adds the specified scheme manager to this Configuration,
Sietse Ringers's avatar
Sietse Ringers committed
630
// provided its signature is valid.
631
func (conf *Configuration) InstallSchemeManager(manager *SchemeManager) error {
632
	name := manager.ID
633
	if err := fs.EnsureDirectoryExists(filepath.Join(conf.Path, name)); err != nil {
634
635
		return err
	}
636
637

	t := NewHTTPTransport(manager.URL)
Sietse Ringers's avatar
Sietse Ringers committed
638
	path := fmt.Sprintf("%s/%s", conf.Path, name)
639
640
641
	if err := t.GetFile("description.xml", path+"/description.xml"); err != nil {
		return err
	}
642
	if err := t.GetFile("pk.pem", path+"/pk.pem"); err != nil {
643
644
		return err
	}
645
	if err := conf.DownloadSchemeManagerSignature(manager); err != nil {
646
647
		return err
	}
648
649
650
651
	conf.SchemeManagers[manager.Identifier()] = manager
	if err := conf.UpdateSchemeManager(manager.Identifier(), nil); err != nil {
		return err
	}
652

653
	return conf.ParseSchemeManagerFolder(filepath.Join(conf.Path, name), manager)
654
655
656
657
658
659
}

// DownloadSchemeManagerSignature downloads, stores and verifies the latest version
// of the index file and signature of the specified manager.
func (conf *Configuration) DownloadSchemeManagerSignature(manager *SchemeManager) (err error) {
	t := NewHTTPTransport(manager.URL)
Sietse Ringers's avatar
Sietse Ringers committed
660
	path := fmt.Sprintf("%s/%s", conf.Path, manager.ID)
661
662
663
664
	index := filepath.Join(path, "index")
	sig := filepath.Join(path, "index.sig")

	if err = t.GetFile("index", index); err != nil {
665
		return
666
667
	}
	if err = t.GetFile("index.sig", sig); err != nil {
668
		return
669
	}
670
	err = conf.VerifySignature(manager.Identifier())
671
	return
672
}
673

Sietse Ringers's avatar
Sietse Ringers committed
674
675
676
// Download downloads the issuers, credential types and public keys specified in set
// if the current Configuration does not already have them,  and checks their authenticity
// using the scheme manager index.
677
678
func (conf *Configuration) Download(session IrmaSession) (downloaded *IrmaIdentifierSet, err error) {
	managers := make(map[string]struct{}) // Managers that we must update
679
	downloaded = &IrmaIdentifierSet{
680
681
682
683
		SchemeManagers:  map[SchemeManagerIdentifier]struct{}{},
		Issuers:         map[IssuerIdentifier]struct{}{},
		CredentialTypes: map[CredentialTypeIdentifier]struct{}{},
	}
684

685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
	// Calculate which scheme managers must be updated
	if err = conf.checkIssuers(session.Identifiers(), managers); err != nil {
		return
	}
	if err = conf.checkCredentialTypes(session, managers); err != nil {
		return
	}

	// Update the scheme managers found above and parse them, if necessary
	for id := range managers {
		if err = conf.UpdateSchemeManager(NewSchemeManagerIdentifier(id), downloaded); err != nil {
			return
		}
	}
	if !downloaded.Empty() {
		return downloaded, conf.ParseFolder()
	}
	return
}

func (conf *Configuration) checkCredentialTypes(session IrmaSession, managers map[string]struct{}) error {
	var disjunctions AttributeDisjunctionList
	var typ *CredentialType
	var contains bool

	switch s := session.(type) {
	case *IssuanceRequest:
		for _, credreq := range s.Credentials {
			// First check if we have this credential type
			typ, contains = conf.CredentialTypes[*credreq.CredentialTypeID]
			if !contains {
				managers[credreq.CredentialTypeID.Root()] = struct{}{}
				continue
			}
			newAttrs := make(map[string]string)
			for k, v := range credreq.Attributes {
				newAttrs[k] = v
			}
			// For each of the attributes in the credentialtype, see if it is present; if so remove it from newAttrs
			// If not, check that it is optional; if not the credentialtype must be updated
			for _, attrtyp := range typ.Attributes {
				_, contains = newAttrs[attrtyp.ID]
				if !contains && !attrtyp.IsOptional() {
					managers[credreq.CredentialTypeID.Root()] = struct{}{}
					break
				}
				delete(newAttrs, attrtyp.ID)
			}
			// If there is anything left in newAttrs, then these are attributes that are not in the credentialtype
			if len(newAttrs) > 0 {
				managers[credreq.CredentialTypeID.Root()] = struct{}{}
			}
		}
		disjunctions = s.Disclose
	case *DisclosureRequest:
		disjunctions = s.Content
	case *SignatureRequest:
		disjunctions = s.Content
	}

	for _, disjunction := range disjunctions {
		for _, attrid := range disjunction.Attributes {
			credid := attrid.CredentialTypeIdentifier()
			if typ, contains = conf.CredentialTypes[credid]; !contains {
				managers[credid.Root()] = struct{}{}
			}
			if !typ.ContainsAttribute(attrid) {
				managers[credid.Root()] = struct{}{}
			}
		}
	}

	return nil
}

func (conf *Configuration) checkIssuers(set *IrmaIdentifierSet, managers map[string]struct{}) error {
761
	for issid := range set.Issuers {
762
		if _, contains := conf.Issuers[issid]; !contains {
763
			managers[issid.Root()] = struct{}{}
764
		}
Sietse Ringers's avatar
Sietse Ringers committed
765
	}
766
767
768
	for issid, keyids := range set.PublicKeys {
		for _, keyid := range keyids {
			pk, err := conf.PublicKey(issid, keyid)
Sietse Ringers's avatar
Sietse Ringers committed
769
			if err != nil {
770
				return err
Sietse Ringers's avatar
Sietse Ringers committed
771
772
			}
			if pk == nil {
773
				managers[issid.Root()] = struct{}{}
774
775
776
			}
		}
	}
777
	return nil
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
}

func (i SchemeManagerIndex) String() string {
	var paths []string
	var b bytes.Buffer

	for path := range i {
		paths = append(paths, path)
	}
	sort.Strings(paths)

	for _, path := range paths {
		b.WriteString(hex.EncodeToString(i[path]))
		b.WriteString(" ")
		b.WriteString(path)
		b.WriteString("\n")
	}

	return b.String()
}

Sietse Ringers's avatar
Sietse Ringers committed
799
// FromString populates this index by parsing the specified string.
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
func (i SchemeManagerIndex) FromString(s string) error {
	for j, line := range strings.Split(s, "\n") {
		if len(line) == 0 {
			continue
		}
		parts := strings.Split(line, " ")
		if len(parts) != 2 {
			return errors.Errorf("Scheme manager index line %d has incorrect amount of parts", j)
		}
		hash, err := hex.DecodeString(parts[0])
		if err != nil {
			return err
		}
		i[parts[1]] = hash
	}

	return nil
}

819
// parseIndex parses the index file of the specified manager.
820
func (conf *Configuration) parseIndex(name string, manager *SchemeManager) (SchemeManagerIndex, error) {
Sietse Ringers's avatar
Sietse Ringers committed
821
	path := filepath.Join(conf.Path, name, "index")
Sietse Ringers's avatar
Sietse Ringers committed
822
	if err := fs.AssertPathExists(path); err != nil {
823
		return nil, fmt.Errorf("Missing scheme manager index file; tried %s", path)
824
	}
Sietse Ringers's avatar
Sietse Ringers committed
825
	indexbts, err := ioutil.ReadFile(path)
826
	if err != nil {
827
		return nil, err
828
	}
829
830
	index := SchemeManagerIndex(make(map[string]ConfigurationFileHash))
	return index, index.FromString(string(indexbts))
831
832
}

833
func (conf *Configuration) VerifySchemeManager(manager *SchemeManager) error {
834
	err := conf.VerifySignature(manager.Identifier())
835
836
837
838
	if err != nil {
		return err
	}

839
	var exists bool
840
	for file := range manager.index {
841
		exists, err = fs.PathExists(filepath.Join(conf.Path, file))
842
843
844
845
846
847
		if err != nil {
			return err
		}
		if !exists {
			continue
		}
848
		// Don't care about the actual bytes
849
		if _, _, err = conf.ReadAuthenticatedFile(manager, file); err != nil {
850
851
852
853
854
855
856
			return err
		}
	}

	return nil
}

857
858
859
// ReadAuthenticatedFile reads the file at the specified path
// and verifies its authenticity by checking that the file hash
// is present in the (signed) scheme manager index file.
860
func (conf *Configuration) ReadAuthenticatedFile(manager *SchemeManager, path string) ([]byte, bool, error) {
861
	signedHash, ok := manager.index[path]
862
	if !ok {
863
		return nil, false, nil
864
865
	}

Sietse Ringers's avatar
Sietse Ringers committed
866
	bts, err := ioutil.ReadFile(filepath.Join(conf.Path, path))
867
	if err != nil {
868
		return nil, true, err
869
870
871
872
	}
	computedHash := sha256.Sum256(bts)

	if !bytes.Equal(computedHash[:], signedHash) {
873
		return nil, true, errors.Errorf("Hash of %s does not match scheme manager index", path)
874
	}
875
	return bts, true, nil
876
877
878
879
880
}

// VerifySignature verifies the signature on the scheme manager index file
// (which contains the SHA256 hashes of all files under this scheme manager,
// which are used for verifying file authenticity).
881
func (conf *Configuration) VerifySignature(id SchemeManagerIdentifier) (err error) {
882
883
884
885
886
887
888
889
890
891
	defer func() {
		if r := recover(); r != nil {
			if e, ok := r.(error); ok {
				err = errors.Errorf("Scheme manager index signature failed to verify: %s", e.Error())
			} else {
				err = errors.New("Scheme manager index signature failed to verify")
			}
		}
	}()

Sietse Ringers's avatar
Sietse Ringers committed
892
	dir := filepath.Join(conf.Path, id.String())
893
	if err := fs.AssertPathExists(dir+"/index", dir+"/index.sig", dir+"/pk.pem"); err != nil {
894
		return errors.New("Missing scheme manager index file, signature, or public key")
895
896
897
898
899
	}

	// Read and hash index file
	indexbts, err := ioutil.ReadFile(dir + "/index")
	if err != nil {
900
		return err
901
902
903
904
905
906
	}
	indexhash := sha256.Sum256(indexbts)

	// Read and parse scheme manager public key
	pkbts, err := ioutil.ReadFile(dir + "/pk.pem")
	if err != nil {
907
		return err
908
909
910
911
	}
	pkblk, _ := pem.Decode(pkbts)
	genericPk, err := x509.ParsePKIXPublicKey(pkblk.Bytes)
	if err != nil {
912
		return err
913
914
915
	}
	pk, ok := genericPk.(*ecdsa.PublicKey)
	if !ok {
916
		return errors.New("Invalid scheme manager public key")
917
918
919
920
921
	}

	// Read and parse signature
	sig, err := ioutil.ReadFile(dir + "/index.sig")
	if err != nil {
922
		return err
923
924
925
926
927
	}
	ints := make([]*big.Int, 0, 2)
	_, err = asn1.Unmarshal(sig, &ints)

	// Verify signature
928
929
930
931
	if !ecdsa.Verify(pk, indexhash[:], ints[0], ints[1]) {
		return errors.New("Scheme manager signature was invalid")
	}
	return nil
932
}
933
934
935
936

func (hash ConfigurationFileHash) String() string {
	return hex.EncodeToString(hash)
}
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952

func (hash ConfigurationFileHash) Equal(other ConfigurationFileHash) bool {
	return bytes.Equal(hash, other)
}

// UpdateSchemeManager syncs the stored version within the irma_configuration directory
// with the remote version at the scheme manager's URL, downloading and storing
// new and modified files, according to the index files of both versions.
// It stores the identifiers of new or updated credential types or issuers in the second parameter.
// Note: any newly downloaded files are not yet parsed and inserted into conf.
func (conf *Configuration) UpdateSchemeManager(id SchemeManagerIdentifier, downloaded *IrmaIdentifierSet) (err error) {
	manager, contains := conf.SchemeManagers[id]
	if !contains {
		return errors.Errorf("Cannot update unknown scheme manager %s", id)
	}

953
954
955
956
957
958
959
960
961
962
	// Check remote timestamp and see if we have to do anything
	transport := NewHTTPTransport(manager.URL + "/")
	timestampBts, err := transport.GetBytes("timestamp")
	if err != nil {
		return err
	}
	timestamp, err := parseTimestamp(timestampBts)
	if err != nil {
		return err
	}
963
	if !manager.Timestamp.Before(*timestamp) {
964
965
966
		return nil
	}

967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
	// Download the new index and its signature, and check that the new index
	// is validly signed by the new signature
	// By aborting immediately in case of error, and restoring backup versions
	// of the index and signature, we leave our stored copy of the scheme manager
	// intact.
	if err = conf.DownloadSchemeManagerSignature(manager); err != nil {
		return
	}
	newIndex, err := conf.parseIndex(manager.ID, manager)
	if err != nil {
		return
	}

	issPattern := regexp.MustCompile("(.+)/(.+)/description\\.xml")
	credPattern := regexp.MustCompile("(.+)/(.+)/Issues/(.+)/description\\.xml")

	// TODO: how to recover/fix local copy if err != nil below?
	for filename, newHash := range newIndex {
985
		path := filepath.Join(conf.Path, filename)
986
		oldHash, known := manager.index[filename]
987
988
989
990
991
992
		var have bool
		have, err = fs.PathExists(path)
		if err != nil {
			return err
		}
		if known && have && oldHash.Equal(newHash) {
993
994
995
996
997
998
999
1000
			continue // nothing to do, we already have this file
		}
		// Ensure that the folder in which to write the file exists
		if err = os.MkdirAll(filepath.Dir(path), 0700); err != nil {
			return err
		}
		stripped := filename[len(manager.ID)+1:] // Scheme manager URL already ends with its name
		// Download the new file, store it in our own irma_configuration folder
1001
		if err = transport.GetSignedFile(stripped, path, newHash); err != nil {
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
			return
		}
		// See if the file is a credential type or issuer, and add it to the downloaded set if so
		if downloaded == nil {
			continue
		}
		var matches []string
		matches = issPattern.FindStringSubmatch(filename)
		if len(matches) == 3 {
			issid := NewIssuerIdentifier(fmt.Sprintf("%s.%s", matches[1], matches[2]))
			downloaded.Issuers[issid] = struct{}{}
		}
		matches = credPattern.FindStringSubmatch(filename)
		if len(matches) == 4 {
			credid := NewCredentialTypeIdentifier(fmt.Sprintf("%s.%s.%s", matches[1], matches[2], matches[3]))
			downloaded.CredentialTypes[credid] = struct{}{}
		}
	}

	manager.index = newIndex
	return
}