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d1c45f5c MW |
1 | ### -*-python-*- |
2 | ### | |
3 | ### Management of a secure password database | |
4 | ### | |
5 | ### (c) 2005 Straylight/Edgeware | |
6 | ### | |
7 | ||
8 | ###----- Licensing notice --------------------------------------------------- | |
9 | ### | |
10 | ### This file is part of the Python interface to Catacomb. | |
11 | ### | |
12 | ### Catacomb/Python is free software; you can redistribute it and/or modify | |
13 | ### it under the terms of the GNU General Public License as published by | |
14 | ### the Free Software Foundation; either version 2 of the License, or | |
15 | ### (at your option) any later version. | |
16 | ### | |
17 | ### Catacomb/Python is distributed in the hope that it will be useful, | |
18 | ### but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | ### GNU General Public License for more details. | |
21 | ### | |
22 | ### You should have received a copy of the GNU General Public License along | |
23 | ### with Catacomb/Python; if not, write to the Free Software Foundation, | |
24 | ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | ||
26 | ###-------------------------------------------------------------------------- | |
27 | ### Imported modules. | |
43c09851 | 28 | |
494b719c MW |
29 | from __future__ import with_statement |
30 | ||
af861fb7 | 31 | import errno as _E |
6baae405 | 32 | import os as _OS |
af861fb7 | 33 | from cStringIO import StringIO as _StringIO |
6baae405 | 34 | |
43c09851 | 35 | import catacomb as _C |
d1c45f5c MW |
36 | |
37 | ###-------------------------------------------------------------------------- | |
af861fb7 MW |
38 | ### Text encoding utilities. |
39 | ||
40 | def _literalp(s): | |
41 | """ | |
42 | Answer whether S can be represented literally. | |
43 | ||
44 | If True, then S can be stored literally, as a metadata item name or | |
45 | value; if False, then S requires some kind of encoding. | |
46 | """ | |
47 | return all(ch.isalnum() or ch in '-_:' for ch in s) | |
48 | ||
49 | def _enc_metaname(name): | |
50 | """Encode NAME as a metadata item name, returning the result.""" | |
51 | if _literalp(name): | |
52 | return name | |
53 | else: | |
54 | sio = _StringIO() | |
55 | sio.write('!') | |
56 | for ch in name: | |
57 | if _literalp(ch): sio.write(ch) | |
58 | elif ch == ' ': sio.write('+') | |
59 | else: sio.write('%%%02x' % ord(ch)) | |
60 | return sio.getvalue() | |
61 | ||
62 | def _dec_metaname(name): | |
63 | """Decode NAME as a metadata item name, returning the result.""" | |
64 | if not name.startswith('!'): | |
65 | return name | |
66 | else: | |
67 | sio = _StringIO() | |
68 | i, n = 1, len(name) | |
69 | while i < n: | |
70 | ch = name[i] | |
71 | i += 1 | |
72 | if ch == '+': | |
73 | sio.write(' ') | |
74 | elif ch == '%': | |
75 | sio.write(chr(int(name[i:i + 2], 16))) | |
76 | i += 2 | |
77 | else: | |
78 | sio.write(ch) | |
79 | return sio.getvalue() | |
80 | ||
81 | def _b64(s): | |
82 | """Encode S as base64, without newlines, and trimming `=' padding.""" | |
83 | return s.encode('base64').translate(None, '\n=') | |
84 | def _unb64(s): | |
85 | """Decode S as base64 with trimmed `=' padding.""" | |
86 | return (s + '='*((4 - len(s))%4)).decode('base64') | |
87 | ||
88 | def _enc_metaval(val): | |
89 | """Encode VAL as a metadata item value, returning the result.""" | |
90 | if _literalp(val): return val | |
91 | else: return '?' + _b64(val) | |
92 | ||
93 | def _dec_metaval(val): | |
94 | """Decode VAL as a metadata item value, returning the result.""" | |
95 | if not val.startswith('?'): return val | |
96 | else: return _unb64(val[1:]) | |
97 | ||
98 | ###-------------------------------------------------------------------------- | |
d1c45f5c MW |
99 | ### Underlying cryptography. |
100 | ||
43c09851 | 101 | class DecryptError (Exception): |
d1c45f5c MW |
102 | """ |
103 | I represent a failure to decrypt a message. | |
104 | ||
105 | Usually this means that someone used the wrong key, though it can also | |
106 | mean that a ciphertext has been modified. | |
107 | """ | |
43c09851 | 108 | pass |
109 | ||
110 | class Crypto (object): | |
d1c45f5c MW |
111 | """ |
112 | I represent a symmetric crypto transform. | |
113 | ||
114 | There's currently only one transform implemented, which is the obvious | |
115 | generic-composition construction: given a message m, and keys K0 and K1, we | |
116 | choose an IV v, and compute: | |
117 | ||
118 | * y = v || E(K0, v; m) | |
119 | * t = M(K1; y) | |
120 | ||
121 | The final ciphertext is t || y. | |
122 | """ | |
123 | ||
43c09851 | 124 | def __init__(me, c, h, m, ck, mk): |
d1c45f5c MW |
125 | """ |
126 | Initialize the Crypto object with a given algorithm selection and keys. | |
127 | ||
128 | We need a GCipher subclass C, a GHash subclass H, a GMAC subclass M, and | |
129 | keys CK and MK for C and M respectively. | |
130 | """ | |
43c09851 | 131 | me.c = c(ck) |
132 | me.m = m(mk) | |
133 | me.h = h | |
d1c45f5c | 134 | |
43c09851 | 135 | def encrypt(me, pt): |
d1c45f5c MW |
136 | """ |
137 | Encrypt the message PT and return the resulting ciphertext. | |
138 | """ | |
9a7b948f MW |
139 | blksz = me.c.__class__.blksz |
140 | b = _C.WriteBuffer() | |
141 | if blksz: | |
142 | iv = _C.rand.block(blksz) | |
43c09851 | 143 | me.c.setiv(iv) |
9a7b948f MW |
144 | b.put(iv) |
145 | b.put(me.c.encrypt(pt)) | |
146 | t = me.m().hash(b).done() | |
147 | return t + str(buffer(b)) | |
148 | ||
43c09851 | 149 | def decrypt(me, ct): |
d1c45f5c MW |
150 | """ |
151 | Decrypt the ciphertext CT, returning the plaintext. | |
152 | ||
153 | Raises DecryptError if anything goes wrong. | |
154 | """ | |
9a7b948f MW |
155 | blksz = me.c.__class__.blksz |
156 | tagsz = me.m.__class__.tagsz | |
157 | b = _C.ReadBuffer(ct) | |
158 | t = b.get(tagsz) | |
159 | h = me.m() | |
160 | if blksz: | |
161 | iv = b.get(blksz) | |
162 | me.c.setiv(iv) | |
163 | h.hash(iv) | |
164 | x = b.get(b.left) | |
165 | h.hash(x) | |
166 | if t != h.done(): raise DecryptError | |
167 | return me.c.decrypt(x) | |
b2687a0a | 168 | |
43c09851 | 169 | class PPK (Crypto): |
d1c45f5c MW |
170 | """ |
171 | I represent a crypto transform whose keys are derived from a passphrase. | |
172 | ||
173 | The password is salted and hashed; the salt is available as the `salt' | |
174 | attribute. | |
175 | """ | |
176 | ||
43c09851 | 177 | def __init__(me, pp, c, h, m, salt = None): |
d1c45f5c MW |
178 | """ |
179 | Initialize the PPK object with a passphrase and algorithm selection. | |
180 | ||
181 | We want a passphrase PP, a GCipher subclass C, a GHash subclass H, a GMAC | |
182 | subclass M, and a SALT. The SALT may be None, if we're generating new | |
183 | keys, indicating that a salt should be chosen randomly. | |
184 | """ | |
43c09851 | 185 | if not salt: salt = _C.rand.block(h.hashsz) |
186 | tag = '%s\0%s' % (pp, salt) | |
187 | Crypto.__init__(me, c, h, m, | |
d1c45f5c MW |
188 | h().hash('cipher:' + tag).done(), |
189 | h().hash('mac:' + tag).done()) | |
43c09851 | 190 | me.salt = salt |
191 | ||
d1c45f5c | 192 | ###-------------------------------------------------------------------------- |
494b719c MW |
193 | ### Backend storage. |
194 | ||
6baae405 MW |
195 | class StorageBackendRefusal (Exception): |
196 | """ | |
197 | I signify that a StorageBackend subclass has refused to open a file. | |
198 | ||
199 | This is used by the StorageBackend.open class method. | |
200 | """ | |
201 | pass | |
202 | ||
203 | class StorageBackendClass (type): | |
204 | """ | |
205 | I am a metaclass for StorageBackend classes. | |
206 | ||
207 | My main feature is that I register my concrete instances (with a `NAME' | |
208 | which is not `None') with the StorageBackend class. | |
209 | """ | |
210 | def __init__(me, name, supers, dict): | |
211 | """ | |
212 | Register a new concrete StorageBackend subclass. | |
213 | """ | |
214 | super(StorageBackendClass, me).__init__(name, supers, dict) | |
215 | if me.NAME is not None: StorageBackend.register_concrete_subclass(me) | |
216 | ||
494b719c MW |
217 | class StorageBackend (object): |
218 | """ | |
1726ab40 MW |
219 | I provide basic protocol for password storage backends. |
220 | ||
221 | I'm an abstract class: you want one of my subclasses if you actually want | |
6baae405 MW |
222 | to do something useful. But I maintain a list of my subclasses and can |
223 | choose an appropriate one to open a database file you've found lying about. | |
494b719c MW |
224 | |
225 | Backends are responsible for storing and retrieving stuff, but not for the | |
226 | cryptographic details. Backends need to store two kinds of information: | |
227 | ||
228 | * metadata, consisting of a number of property names and their values; | |
229 | and | |
230 | ||
231 | * password mappings, consisting of a number of binary labels and | |
232 | payloads. | |
1726ab40 MW |
233 | |
234 | Backends need to implement the following ordinary methods. See the calling | |
235 | methods for details of the subclass responsibilities. | |
236 | ||
237 | BE._create(FILE) Create a new database in FILE; used by `create'. | |
238 | ||
239 | BE._open(FILE, WRITEP) | |
240 | Open the existing database FILE; used by `open'. | |
241 | ||
053c2659 MW |
242 | BE._close(ABRUPTP) Close the database, freeing up any resources. If |
243 | ABRUPTP then don't try to commit changes. | |
1726ab40 MW |
244 | |
245 | BE._get_meta(NAME, DEFAULT) | |
246 | Return the value of the metadata item with the given | |
247 | NAME, or DEFAULT if it doesn't exist; used by | |
248 | `get_meta'. | |
249 | ||
250 | BE._put_meta(NAME, VALUE) | |
251 | Set the VALUE of the metadata item with the given | |
252 | NAME, creating one if necessary; used by `put_meta'. | |
253 | ||
254 | BE._del_meta(NAME) Forget the metadata item with the given NAME; raise | |
255 | `KeyError' if there is no such item; used by | |
256 | `del_meta'. | |
257 | ||
258 | BE._iter_meta() Return an iterator over the metadata (NAME, VALUE) | |
259 | pairs; used by `iter_meta'. | |
260 | ||
261 | BE._get_passwd(LABEL) | |
262 | Return the password payload stored with the (binary) | |
263 | LABEL; used by `get_passwd'. | |
264 | ||
265 | BE._put_passwd(LABEL, PAYLOAD) | |
266 | Associate the (binary) PAYLOAD with the LABEL, | |
267 | forgetting any previous payload for that LABEL; used | |
268 | by `put_passwd'. | |
269 | ||
270 | BE._del_passwd(LABEL) Forget the password record with the given LABEL; used | |
271 | by `_del_passwd'. | |
272 | ||
273 | BE._iter_passwds() Return an iterator over the password (LABEL, PAYLOAD) | |
274 | pairs; used by `iter_passwds'. | |
6baae405 MW |
275 | |
276 | Also, concrete subclasses should define the following class attributes. | |
277 | ||
278 | NAME The name of the backend, so that the user can select | |
279 | it when creating a new database. | |
280 | ||
281 | PRIO An integer priority: backends are tried in decreasing | |
282 | priority order when opening an existing database. | |
494b719c MW |
283 | """ |
284 | ||
6baae405 MW |
285 | __metaclass__ = StorageBackendClass |
286 | NAME = None | |
287 | PRIO = 10 | |
288 | ||
289 | ## The registry of subclasses. | |
290 | CLASSES = {} | |
291 | ||
494b719c MW |
292 | FAIL = ['FAIL'] |
293 | ||
6baae405 MW |
294 | @staticmethod |
295 | def register_concrete_subclass(sub): | |
296 | """Register a concrete subclass, so that `open' can try it.""" | |
297 | StorageBackend.CLASSES[sub.NAME] = sub | |
298 | ||
299 | @staticmethod | |
300 | def byname(name): | |
301 | """ | |
302 | Return the concrete subclass with the given NAME. | |
303 | ||
304 | Raise `KeyError' if the name isn't found. | |
305 | """ | |
306 | return StorageBackend.CLASSES[name] | |
307 | ||
308 | @staticmethod | |
309 | def classes(): | |
310 | """Return an iterator over the concrete subclasses.""" | |
311 | return StorageBackend.CLASSES.itervalues() | |
312 | ||
313 | @staticmethod | |
314 | def open(file, writep = False): | |
315 | """Open a database FILE, using some appropriate backend.""" | |
316 | _OS.stat(file) | |
317 | for cls in sorted(StorageBackend.CLASSES.values(), reverse = True, | |
318 | key = lambda cls: cls.PRIO): | |
319 | try: return cls(file, writep) | |
320 | except StorageBackendRefusal: pass | |
321 | raise StorageBackendRefusal | |
494b719c MW |
322 | |
323 | @classmethod | |
324 | def create(cls, file): | |
1726ab40 MW |
325 | """ |
326 | Create a new database in the named FILE, using this backend. | |
327 | ||
328 | Subclasses must implement the `_create' instance method. | |
329 | """ | |
494b719c | 330 | return cls(writep = True, _magic = lambda me: me._create(file)) |
494b719c MW |
331 | |
332 | def __init__(me, file = None, writep = False, _magic = None, *args, **kw): | |
333 | """ | |
334 | Main constructor. | |
1726ab40 MW |
335 | |
336 | Subclasses are not, in general, expected to override this: there's a | |
337 | somewhat hairy protocol between the constructor and some of the class | |
338 | methods. Instead, the main hook for customization is the subclass's | |
339 | `_open' method, which is invoked in the usual case. | |
494b719c MW |
340 | """ |
341 | super(StorageBackend, me).__init__(*args, **kw) | |
6baae405 | 342 | if me.NAME is None: raise ValueError, 'abstract class' |
494b719c MW |
343 | if _magic is not None: _magic(me) |
344 | elif file is None: raise ValueError, 'missing file parameter' | |
1726ab40 | 345 | else: me._open(file, writep) |
494b719c MW |
346 | me._writep = writep |
347 | me._livep = True | |
348 | ||
053c2659 | 349 | def close(me, abruptp = False): |
494b719c MW |
350 | """ |
351 | Close the database. | |
352 | ||
353 | It is harmless to attempt to close a database which has been closed | |
1726ab40 | 354 | already. Calls the subclass's `_close' method. |
494b719c MW |
355 | """ |
356 | if me._livep: | |
357 | me._livep = False | |
053c2659 | 358 | me._close(abruptp) |
494b719c MW |
359 | |
360 | ## Utilities. | |
361 | ||
362 | def _check_live(me): | |
363 | """Raise an error if the receiver has been closed.""" | |
364 | if not me._livep: raise ValueError, 'database is closed' | |
365 | ||
366 | def _check_write(me): | |
367 | """Raise an error if the receiver is not open for writing.""" | |
368 | me._check_live() | |
369 | if not me._writep: raise ValueError, 'database is read-only' | |
370 | ||
371 | def _check_meta_name(me, name): | |
372 | """ | |
373 | Raise an error unless NAME is a valid name for a metadata item. | |
374 | ||
375 | Metadata names may not start with `$': such names are reserved for | |
376 | password storage. | |
377 | """ | |
378 | if name.startswith('$'): | |
379 | raise ValueError, "invalid metadata key `%s'" % name | |
380 | ||
381 | ## Context protocol. | |
382 | ||
383 | def __enter__(me): | |
384 | """Context protocol: make sure the database is closed on exit.""" | |
385 | return me | |
386 | def __exit__(me, exctype, excvalue, exctb): | |
387 | """Context protocol: see `__enter__'.""" | |
053c2659 | 388 | me.close(excvalue is not None) |
494b719c MW |
389 | |
390 | ## Metadata. | |
391 | ||
392 | def get_meta(me, name, default = FAIL): | |
393 | """ | |
394 | Fetch the value for the metadata item NAME. | |
395 | ||
396 | If no such item exists, then return DEFAULT if that was set; otherwise | |
397 | raise a `KeyError'. | |
1726ab40 MW |
398 | |
399 | This calls the subclass's `_get_meta' method, which should return the | |
400 | requested item or return the given DEFAULT value. It may assume that the | |
401 | name is valid and the database is open. | |
494b719c MW |
402 | """ |
403 | me._check_meta_name(name) | |
404 | me._check_live() | |
1726ab40 | 405 | value = me._get_meta(name, default) |
494b719c MW |
406 | if value is StorageBackend.FAIL: raise KeyError, name |
407 | return value | |
408 | ||
409 | def put_meta(me, name, value): | |
1726ab40 MW |
410 | """ |
411 | Store VALUE in the metadata item called NAME. | |
412 | ||
413 | This calls the subclass's `_put_meta' method, which may assume that the | |
414 | name is valid and the database is open for writing. | |
415 | """ | |
494b719c MW |
416 | me._check_meta_name(name) |
417 | me._check_write() | |
1726ab40 | 418 | me._put_meta(name, value) |
494b719c MW |
419 | |
420 | def del_meta(me, name): | |
1726ab40 MW |
421 | """ |
422 | Forget about the metadata item with the given NAME. | |
423 | ||
424 | This calls the subclass's `_del_meta' method, which may assume that the | |
425 | name is valid and the database is open for writing. | |
426 | """ | |
494b719c MW |
427 | me._check_meta_name(name) |
428 | me._check_write() | |
1726ab40 | 429 | me._del_meta(name) |
494b719c MW |
430 | |
431 | def iter_meta(me): | |
1726ab40 MW |
432 | """ |
433 | Return an iterator over the name/value metadata items. | |
494b719c | 434 | |
1726ab40 MW |
435 | This calls the subclass's `_iter_meta' method, which may assume that the |
436 | database is open. | |
437 | """ | |
438 | me._check_live() | |
439 | return me._iter_meta() | |
494b719c MW |
440 | |
441 | def get_passwd(me, label): | |
442 | """ | |
443 | Fetch and return the payload stored with the (opaque, binary) LABEL. | |
444 | ||
445 | If there is no such payload then raise `KeyError'. | |
1726ab40 MW |
446 | |
447 | This calls the subclass's `_get_passwd' method, which may assume that the | |
448 | database is open. | |
494b719c MW |
449 | """ |
450 | me._check_live() | |
1726ab40 | 451 | return me._get_passwd(label) |
494b719c MW |
452 | |
453 | def put_passwd(me, label, payload): | |
454 | """ | |
455 | Associate the (opaque, binary) PAYLOAD with the (opaque, binary) LABEL. | |
456 | ||
457 | Any previous payload for LABEL is forgotten. | |
1726ab40 MW |
458 | |
459 | This calls the subclass's `_put_passwd' method, which may assume that the | |
460 | database is open for writing. | |
494b719c MW |
461 | """ |
462 | me._check_write() | |
1726ab40 | 463 | me._put_passwd(label, payload) |
494b719c MW |
464 | |
465 | def del_passwd(me, label): | |
466 | """ | |
467 | Forget any PAYLOAD associated with the (opaque, binary) LABEL. | |
468 | ||
469 | If there is no such payload then raise `KeyError'. | |
1726ab40 MW |
470 | |
471 | This calls the subclass's `_del_passwd' method, which may assume that the | |
472 | database is open for writing. | |
494b719c MW |
473 | """ |
474 | me._check_write() | |
1726ab40 | 475 | me._del_passwd(label, payload) |
494b719c MW |
476 | |
477 | def iter_passwds(me): | |
1726ab40 MW |
478 | """ |
479 | Return an iterator over the stored password label/payload pairs. | |
480 | ||
481 | This calls the subclass's `_iter_passwds' method, which may assume that | |
482 | the database is open. | |
483 | """ | |
494b719c | 484 | me._check_live() |
1726ab40 MW |
485 | return me._iter_passwds() |
486 | ||
8501dc39 MW |
487 | try: import gdbm as _G |
488 | except ImportError: pass | |
489 | else: | |
490 | class GDBMStorageBackend (StorageBackend): | |
491 | """ | |
492 | My instances store password data in a GDBM database. | |
1726ab40 | 493 | |
8501dc39 MW |
494 | Metadata and password entries are mixed into the same database. The key |
495 | for a metadata item is simply its name; the key for a password entry is | |
496 | the entry's label prefixed by `$', since we're guaranteed that no | |
497 | metadata item name begins with `$'. | |
498 | """ | |
1726ab40 | 499 | |
8501dc39 | 500 | NAME = 'gdbm' |
6baae405 | 501 | |
8501dc39 MW |
502 | def _open(me, file, writep): |
503 | try: me._db = _G.open(file, writep and 'w' or 'r') | |
504 | except _G.error, e: raise StorageBackendRefusal, e | |
1726ab40 | 505 | |
8501dc39 MW |
506 | def _create(me, file): |
507 | me._db = _G.open(file, 'n', 0600) | |
1726ab40 | 508 | |
8501dc39 MW |
509 | def _close(me, abruptp): |
510 | me._db.close() | |
511 | me._db = None | |
1726ab40 | 512 | |
8501dc39 MW |
513 | def _get_meta(me, name, default): |
514 | try: return me._db[name] | |
515 | except KeyError: return default | |
1726ab40 | 516 | |
8501dc39 MW |
517 | def _put_meta(me, name, value): |
518 | me._db[name] = value | |
1726ab40 | 519 | |
8501dc39 MW |
520 | def _del_meta(me, name): |
521 | del me._db[name] | |
1726ab40 | 522 | |
8501dc39 MW |
523 | def _iter_meta(me): |
524 | k = me._db.firstkey() | |
525 | while k is not None: | |
526 | if not k.startswith('$'): yield k, me._db[k] | |
527 | k = me._db.nextkey(k) | |
1726ab40 | 528 | |
8501dc39 MW |
529 | def _get_passwd(me, label): |
530 | return me._db['$' + label] | |
1726ab40 | 531 | |
8501dc39 MW |
532 | def _put_passwd(me, label, payload): |
533 | me._db['$' + label] = payload | |
1726ab40 | 534 | |
8501dc39 MW |
535 | def _del_passwd(me, label): |
536 | del me._db['$' + label] | |
1726ab40 | 537 | |
8501dc39 MW |
538 | def _iter_passwds(me): |
539 | k = me._db.firstkey() | |
540 | while k is not None: | |
541 | if k.startswith('$'): yield k[1:], me._db[k] | |
542 | k = me._db.nextkey(k) | |
494b719c | 543 | |
af861fb7 MW |
544 | class PlainTextBackend (StorageBackend): |
545 | """ | |
546 | I'm a utility base class for storage backends which use plain text files. | |
547 | ||
548 | I provide subclasses with the following capabilities. | |
549 | ||
550 | * Creating files, with given modes, optionally ensuring that the file | |
551 | doesn't exist already. | |
552 | ||
553 | * Parsing flat text files, checking leading magic, skipping comments, and | |
554 | providing standard encodings of troublesome characters and binary | |
555 | strings in metadata and password records. See below. | |
556 | ||
557 | * Maintenance of metadata and password records in in-memory dictionaries, | |
558 | with ready implementations of the necessary StorageBackend subclass | |
559 | responsibility methods. (Subclasses can override these if they want to | |
560 | make different arrangements.) | |
561 | ||
562 | Metadata records are written with an optional prefix string chosen by the | |
563 | caller, followed by a `NAME=VALUE' pair. The NAME is form-urlencoded and | |
564 | prefixed with `!' if it contains strange characters; the VALUE is base64- | |
565 | encoded (without the pointless trailing `=' padding) and prefixed with `?' | |
566 | if necessary. | |
567 | ||
568 | Password records are written with an optional prefix string chosen by the | |
569 | caller, followed by a LABEL=PAYLOAD pair, both of which are base64-encoded | |
570 | (without padding). | |
571 | ||
572 | The following attributes are available for subclasses: | |
573 | ||
574 | _meta Dictionary mapping metadata item names to their values. | |
575 | Populated by `_parse_meta' and managed by `_get_meta' and | |
576 | friends. | |
577 | ||
578 | _pw Dictionary mapping password labels to encrypted payloads. | |
579 | Populated by `_parse_passwd' and managed by `_get_passwd' and | |
580 | friends. | |
581 | ||
582 | _dirtyp Boolean: set if either of the dictionaries has been modified. | |
583 | """ | |
584 | ||
585 | def __init__(me, *args, **kw): | |
586 | """ | |
587 | Hook for initialization. | |
588 | ||
589 | Sets up the published instance attributes. | |
590 | """ | |
591 | me._meta = {} | |
592 | me._pw = {} | |
593 | me._dirtyp = False | |
594 | super(PlainTextBackend, me).__init__(*args, **kw) | |
595 | ||
596 | def _create_file(me, file, mode = 0600, freshp = False): | |
597 | """ | |
598 | Make sure FILE exists, creating it with the given MODE if necessary. | |
599 | ||
600 | If FRESHP is true, then make sure the file did not exist previously. | |
601 | Return a file object for the newly created file. | |
602 | """ | |
603 | flags = _OS.O_CREAT | _OS.O_WRONLY | |
604 | if freshp: flags |= _OS.O_EXCL | |
605 | else: flags |= _OS.O_TRUNC | |
606 | fd = _OS.open(file, flags, mode) | |
607 | return _OS.fdopen(fd, 'w') | |
608 | ||
609 | def _mark_dirty(me): | |
610 | """ | |
611 | Set the `_dirtyp' flag. | |
612 | ||
613 | Subclasses might find it useful to intercept this method. | |
614 | """ | |
615 | me._dirtyp = True | |
616 | ||
617 | def _eqsplit(me, line): | |
618 | """ | |
619 | Extract the KEY, VALUE pair from a LINE of the form `KEY=VALUE'. | |
620 | ||
621 | Raise `ValueError' if there is no `=' in the LINE. | |
622 | """ | |
623 | eq = line.index('=') | |
624 | return line[:eq], line[eq + 1:] | |
625 | ||
626 | def _parse_file(me, file, magic = None): | |
627 | """ | |
628 | Parse a FILE. | |
629 | ||
630 | Specifically: | |
631 | ||
632 | * Raise `StorageBackendRefusal' if that the first line doesn't match | |
633 | MAGIC (if provided). MAGIC should not contain the terminating | |
634 | newline. | |
635 | ||
636 | * Ignore comments (beginning `#') and blank lines. | |
637 | ||
638 | * Call `_parse_line' (provided by the subclass) for other lines. | |
639 | """ | |
640 | with open(file, 'r') as f: | |
641 | if magic is not None: | |
642 | if f.readline().rstrip('\n') != magic: raise StorageBackendRefusal | |
643 | for line in f: | |
644 | line = line.rstrip('\n') | |
645 | if not line or line.startswith('#'): continue | |
646 | me._parse_line(line) | |
647 | ||
648 | def _write_file(me, file, writebody, mode = 0600, magic = None): | |
649 | """ | |
650 | Update FILE atomically. | |
651 | ||
652 | The newly created file will have the given MODE. If MAGIC is given, then | |
653 | write that as the first line. Calls WRITEBODY(F) to write the main body | |
654 | of the file where F is a file object for the new file. | |
655 | """ | |
656 | new = file + '.new' | |
657 | with me._create_file(new, mode) as f: | |
658 | if magic is not None: f.write(magic + '\n') | |
659 | writebody(f) | |
660 | _OS.rename(new, file) | |
661 | ||
662 | def _parse_meta(me, line): | |
663 | """Parse LINE as a metadata NAME=VALUE pair, and updates `_meta'.""" | |
664 | k, v = me._eqsplit(line) | |
665 | me._meta[_dec_metaname(k)] = _dec_metaval(v) | |
666 | ||
667 | def _write_meta(me, f, prefix = ''): | |
668 | """Write the metadata records to F, each with the given PREFIX.""" | |
669 | f.write('\n## Metadata.\n') | |
670 | for k, v in me._meta.iteritems(): | |
671 | f.write('%s%s=%s\n' % (prefix, _enc_metaname(k), _enc_metaval(v))) | |
672 | ||
673 | def _get_meta(me, name, default): | |
674 | return me._meta.get(name, default) | |
675 | def _put_meta(me, name, value): | |
676 | me._mark_dirty() | |
677 | me._meta[name] = value | |
678 | def _del_meta(me, name): | |
679 | me._mark_dirty() | |
680 | del me._meta[name] | |
681 | def _iter_meta(me): | |
682 | return me._meta.iteritems() | |
683 | ||
684 | def _parse_passwd(me, line): | |
685 | """Parse LINE as a password LABEL=PAYLOAD pair, and updates `_pw'.""" | |
686 | k, v = me._eqsplit(line) | |
687 | me._pw[_unb64(k)] = _unb64(v) | |
688 | ||
689 | def _write_passwd(me, f, prefix = ''): | |
690 | """Write the password records to F, each with the given PREFIX.""" | |
691 | f.write('\n## Password data.\n') | |
692 | for k, v in me._pw.iteritems(): | |
693 | f.write('%s%s=%s\n' % (prefix, _b64(k), _b64(v))) | |
694 | ||
695 | def _get_passwd(me, label): | |
696 | return me._pw[str(label)] | |
697 | def _put_passwd(me, label, payload): | |
698 | me._mark_dirty() | |
699 | me._pw[str(label)] = payload | |
700 | def _del_passwd(me, label): | |
701 | me._mark_dirty() | |
702 | del me._pw[str(label)] | |
703 | def _iter_passwds(me): | |
704 | return me._pw.iteritems() | |
705 | ||
706 | class FlatFileStorageBackend (PlainTextBackend): | |
707 | """ | |
708 | I maintain a password database in a plain text file. | |
709 | ||
710 | The text file consists of lines, as follows. | |
711 | ||
712 | * Empty lines, and lines beginning with `#' (in the leftmost column only) | |
713 | are ignored. | |
714 | ||
715 | * Lines of the form `$LABEL=PAYLOAD' store password data. Both LABEL and | |
716 | PAYLOAD are base64-encoded, without `=' padding. | |
717 | ||
718 | * Lines of the form `NAME=VALUE' store metadata. If the NAME contains | |
719 | characters other than alphanumerics, hyphens, underscores, and colons, | |
720 | then it is form-urlencoded, and prefixed wth `!'. If the VALUE | |
721 | contains such characters, then it is base64-encoded, without `=' | |
722 | padding, and prefixed with `?'. | |
723 | ||
724 | * Other lines are erroneous. | |
725 | ||
726 | The file is rewritten from scratch when it's changed: any existing | |
727 | commentary is lost, and items may be reordered. There is no file locking, | |
728 | but the file is updated atomically, by renaming. | |
729 | ||
730 | It is expected that the FlatFileStorageBackend is used mostly for | |
731 | diagnostics and transfer, rather than for a live system. | |
732 | """ | |
733 | ||
734 | NAME = 'flat' | |
735 | PRIO = 0 | |
736 | MAGIC = '### pwsafe password database' | |
737 | ||
738 | def _open(me, file, writep): | |
739 | if not _OS.path.isfile(file): raise StorageBackendRefusal | |
740 | me._parse_file(file, magic = me.MAGIC) | |
741 | def _parse_line(me, line): | |
742 | if line.startswith('$'): me._parse_passwd(line[1:]) | |
743 | else: me._parse_meta(line) | |
744 | ||
745 | def _create(me, file): | |
746 | with me._create_file(file, freshp = True) as f: pass | |
747 | me._file = file | |
748 | me._mark_dirty() | |
749 | ||
750 | def _close(me, abruptp): | |
751 | if not abruptp and me._dirtyp: | |
752 | me._write_file(me._file, me._write_body, magic = me.MAGIC) | |
753 | ||
754 | def _write_body(me, f): | |
755 | me._write_meta(f) | |
756 | me._write_passwd(f, '$') | |
757 | ||
b61e9efe MW |
758 | class DirectoryStorageBackend (PlainTextBackend): |
759 | """ | |
760 | I maintain a password database in a directory, with one file per password. | |
761 | ||
762 | This makes password databases easy to maintain in a revision-control system | |
763 | such as Git. | |
764 | ||
765 | The directory is structured as follows. | |
766 | ||
767 | dir/meta Contains metadata, similar to the `FlatFileBackend'. | |
768 | ||
769 | dir/pw/LABEL Contains the (raw binary) payload for the given password | |
770 | LABEL (base64-encoded, without the useless `=' padding, and | |
771 | with `/' replaced by `.'). | |
772 | ||
773 | dir/tmp/ Contains temporary files used by the implementation. | |
774 | """ | |
775 | ||
776 | NAME = 'dir' | |
777 | METAMAGIC = '### pwsafe password directory metadata' | |
778 | ||
779 | def _open(me, file, writep): | |
780 | if not _OS.path.isdir(file) or \ | |
781 | not _OS.path.isdir(_OS.path.join(file, 'pw')) or \ | |
782 | not _OS.path.isdir(_OS.path.join(file, 'tmp')) or \ | |
783 | not _OS.path.isfile(_OS.path.join(file, 'meta')): | |
784 | raise StorageBackendRefusal | |
785 | me._dir = file | |
786 | me._parse_file(_OS.path.join(file, 'meta'), magic = me.METAMAGIC) | |
787 | def _parse_line(me, line): | |
788 | me._parse_meta(line) | |
789 | ||
790 | def _create(me, file): | |
791 | _OS.mkdir(file, 0700) | |
792 | _OS.mkdir(_OS.path.join(file, 'pw'), 0700) | |
793 | _OS.mkdir(_OS.path.join(file, 'tmp'), 0700) | |
794 | me._mark_dirty() | |
795 | me._dir = file | |
796 | ||
797 | def _close(me, abruptp): | |
798 | if not abruptp and me._dirtyp: | |
799 | me._write_file(_OS.path.join(me._dir, 'meta'), | |
800 | me._write_meta, magic = me.METAMAGIC) | |
801 | ||
802 | def _pwfile(me, label, dir = 'pw'): | |
803 | return _OS.path.join(me._dir, dir, _b64(label).replace('/', '.')) | |
804 | def _get_passwd(me, label): | |
805 | try: | |
806 | f = open(me._pwfile(label), 'rb') | |
807 | except (OSError, IOError), e: | |
808 | if e.errno == _E.ENOENT: raise KeyError, label | |
809 | else: raise | |
810 | with f: return f.read() | |
811 | def _put_passwd(me, label, payload): | |
812 | new = me._pwfile(label, 'tmp') | |
813 | fd = _OS.open(new, _OS.O_WRONLY | _OS.O_CREAT | _OS.O_TRUNC, 0600) | |
814 | _OS.close(fd) | |
815 | with open(new, 'wb') as f: f.write(payload) | |
816 | _OS.rename(new, me._pwfile(label)) | |
817 | def _del_passwd(me, label): | |
818 | try: | |
819 | _OS.remove(me._pwfile(label)) | |
820 | except (OSError, IOError), e: | |
821 | if e == _E.ENOENT: raise KeyError, label | |
822 | else: raise | |
823 | def _iter_passwds(me): | |
824 | pw = _OS.path.join(me._dir, 'pw') | |
825 | for i in _OS.listdir(pw): | |
826 | with open(_OS.path.join(pw, i), 'rb') as f: pld = f.read() | |
827 | yield _unb64(i.replace('.', '/')), pld | |
828 | ||
494b719c | 829 | ###-------------------------------------------------------------------------- |
d1c45f5c | 830 | ### Password storage. |
43c09851 | 831 | |
43c09851 | 832 | class PW (object): |
d1c45f5c MW |
833 | """ |
834 | I represent a secure (ish) password store. | |
835 | ||
836 | I can store short secrets, associated with textual names, in a way which | |
837 | doesn't leak too much information about them. | |
838 | ||
2119e334 | 839 | I implement (some of) the Python mapping protocol. |
d1c45f5c | 840 | |
494b719c MW |
841 | I keep track of everything using a StorageBackend object. This contains |
842 | password entries, identified by cryptographic labels, and a number of | |
843 | metadata items. | |
d1c45f5c MW |
844 | |
845 | cipher Names the Catacomb cipher selected. | |
846 | ||
847 | hash Names the Catacomb hash function selected. | |
848 | ||
849 | key Cipher and MAC keys, each prefixed by a 16-bit big-endian | |
850 | length and concatenated, encrypted using the master | |
851 | passphrase. | |
852 | ||
853 | mac Names the Catacomb message authentication code selected. | |
854 | ||
855 | magic A magic string for obscuring password tag names. | |
856 | ||
857 | salt The salt for hashing the passphrase. | |
858 | ||
859 | tag The master passphrase's tag, for the Pixie's benefit. | |
860 | ||
494b719c MW |
861 | Password entries are assigned labels of the form `$' || H(MAGIC || TAG); |
862 | the corresponding value consists of a pair (TAG, PASSWD), prefixed with | |
863 | 16-bit lengths, concatenated, padded to a multiple of 256 octets, and | |
864 | encrypted using the stored keys. | |
d1c45f5c MW |
865 | """ |
866 | ||
4a35c9a7 | 867 | def __init__(me, file, writep = False): |
d1c45f5c | 868 | """ |
494b719c | 869 | Initialize a PW object from the database in FILE. |
d1c45f5c | 870 | |
494b719c MW |
871 | If WRITEP is false (the default) then the database is opened read-only; |
872 | if true then it may be written. Requests the database password from the | |
873 | Pixie, which may cause interaction. | |
d1c45f5c MW |
874 | """ |
875 | ||
876 | ## Open the database. | |
6baae405 | 877 | me.db = StorageBackend.open(file, writep) |
d1c45f5c MW |
878 | |
879 | ## Find out what crypto to use. | |
494b719c MW |
880 | c = _C.gcciphers[me.db.get_meta('cipher')] |
881 | h = _C.gchashes[me.db.get_meta('hash')] | |
882 | m = _C.gcmacs[me.db.get_meta('mac')] | |
d1c45f5c MW |
883 | |
884 | ## Request the passphrase and extract the master keys. | |
494b719c MW |
885 | tag = me.db.get_meta('tag') |
886 | ppk = PPK(_C.ppread(tag), c, h, m, me.db.get_meta('salt')) | |
43c09851 | 887 | try: |
494b719c | 888 | b = _C.ReadBuffer(ppk.decrypt(me.db.get_meta('key'))) |
43c09851 | 889 | except DecryptError: |
890 | _C.ppcancel(tag) | |
891 | raise | |
9a7b948f MW |
892 | me.ck = b.getblk16() |
893 | me.mk = b.getblk16() | |
894 | if not b.endp: raise ValueError, 'trailing junk' | |
d1c45f5c MW |
895 | |
896 | ## Set the key, and stash it and the tag-hashing secret. | |
43c09851 | 897 | me.k = Crypto(c, h, m, me.ck, me.mk) |
494b719c | 898 | me.magic = me.k.decrypt(me.db.get_meta('magic')) |
d1c45f5c | 899 | |
09b8041d | 900 | @classmethod |
6baae405 | 901 | def create(cls, dbcls, file, tag, c, h, m): |
09b8041d | 902 | """ |
6baae405 | 903 | Create and initialize a new database FILE using StorageBackend DBCLS. |
09b8041d MW |
904 | |
905 | We want a GCipher subclass C, a GHash subclass H, and a GMAC subclass M; | |
906 | and a Pixie passphrase TAG. | |
907 | ||
908 | This doesn't return a working object: it just creates the database file | |
909 | and gets out of the way. | |
910 | """ | |
911 | ||
912 | ## Set up the cryptography. | |
913 | pp = _C.ppread(tag, _C.PMODE_VERIFY) | |
914 | ppk = PPK(pp, c, h, m) | |
915 | ck = _C.rand.block(c.keysz.default) | |
916 | mk = _C.rand.block(c.keysz.default) | |
917 | k = Crypto(c, h, m, ck, mk) | |
918 | ||
919 | ## Set up and initialize the database. | |
494b719c | 920 | kct = ppk.encrypt(_C.WriteBuffer().putblk16(ck).putblk16(mk)) |
6baae405 | 921 | with dbcls.create(file) as db: |
494b719c MW |
922 | db.put_meta('tag', tag) |
923 | db.put_meta('salt', ppk.salt) | |
924 | db.put_meta('cipher', c.name) | |
925 | db.put_meta('hash', h.name) | |
926 | db.put_meta('mac', m.name) | |
927 | db.put_meta('key', kct) | |
928 | db.put_meta('magic', k.encrypt(_C.rand.block(h.hashsz))) | |
09b8041d | 929 | |
43c09851 | 930 | def keyxform(me, key): |
494b719c MW |
931 | """Transform the KEY (actually a password tag) into a password label.""" |
932 | return me.k.h().hash(me.magic).hash(key).done() | |
d1c45f5c | 933 | |
43c09851 | 934 | def changepp(me): |
d1c45f5c MW |
935 | """ |
936 | Change the database password. | |
937 | ||
938 | Requests the new password from the Pixie, which will probably cause | |
939 | interaction. | |
940 | """ | |
494b719c | 941 | tag = me.db.get_meta('tag') |
43c09851 | 942 | _C.ppcancel(tag) |
943 | ppk = PPK(_C.ppread(tag, _C.PMODE_VERIFY), | |
d1c45f5c | 944 | me.k.c.__class__, me.k.h, me.k.m.__class__) |
494b719c MW |
945 | kct = ppk.encrypt(_C.WriteBuffer().putblk16(me.ck).putblk16(me.mk)) |
946 | me.db.put_meta('key', kct) | |
947 | me.db.put_meta('salt', ppk.salt) | |
d1c45f5c | 948 | |
43c09851 | 949 | def pack(me, key, value): |
494b719c | 950 | """Pack the KEY and VALUE into a ciphertext, and return it.""" |
9a7b948f MW |
951 | b = _C.WriteBuffer() |
952 | b.putblk16(key).putblk16(value) | |
953 | b.zero(((b.size + 255) & ~255) - b.size) | |
954 | return me.k.encrypt(b) | |
d1c45f5c MW |
955 | |
956 | def unpack(me, ct): | |
957 | """ | |
958 | Unpack a ciphertext CT and return a (KEY, VALUE) pair. | |
959 | ||
960 | Might raise DecryptError, of course. | |
961 | """ | |
9a7b948f MW |
962 | b = _C.ReadBuffer(me.k.decrypt(ct)) |
963 | key = b.getblk16() | |
964 | value = b.getblk16() | |
43c09851 | 965 | return key, value |
d1c45f5c MW |
966 | |
967 | ## Mapping protocol. | |
968 | ||
43c09851 | 969 | def __getitem__(me, key): |
494b719c MW |
970 | """Return the password for the given KEY.""" |
971 | try: return me.unpack(me.db.get_passwd(me.keyxform(key)))[1] | |
972 | except KeyError: raise KeyError, key | |
d1c45f5c | 973 | |
43c09851 | 974 | def __setitem__(me, key, value): |
494b719c MW |
975 | """Associate the password VALUE with the KEY.""" |
976 | me.db.put_passwd(me.keyxform(key), me.pack(key, value)) | |
d1c45f5c | 977 | |
43c09851 | 978 | def __delitem__(me, key): |
494b719c MW |
979 | """Forget all about the KEY.""" |
980 | try: me.db.del_passwd(me.keyxform(key)) | |
981 | except KeyError: raise KeyError, key | |
d1c45f5c | 982 | |
43c09851 | 983 | def __iter__(me): |
494b719c MW |
984 | """Iterate over the known password tags.""" |
985 | for _, pld in me.db.iter_passwds(): | |
986 | yield me.unpack(pld)[0] | |
43c09851 | 987 | |
5bf6e9f5 MW |
988 | ## Context protocol. |
989 | ||
990 | def __enter__(me): | |
991 | return me | |
992 | def __exit__(me, excty, excval, exctb): | |
053c2659 | 993 | me.db.close(excval is not None) |
5bf6e9f5 | 994 | |
d1c45f5c | 995 | ###----- That's all, folks -------------------------------------------------- |