pk.cpp 14.8 KB
Newer Older
1
/* Copyright 2018, 2019 New Vector Ltd
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include "olm/pk.h"
#include "olm/cipher.h"
#include "olm/crypto.h"
#include "olm/ratchet.hh"
#include "olm/error.h"
#include "olm/memory.hh"
#include "olm/base64.hh"
22
23
#include "olm/pickle_encoding.h"
#include "olm/pickle.hh"
24
25
26

static const std::size_t MAC_LENGTH = 8;

27
const struct _olm_cipher_aes_sha_256 olm_pk_cipher_aes_sha256 =
28
29
30
31
    OLM_CIPHER_INIT_AES_SHA_256("");
const struct _olm_cipher *olm_pk_cipher =
    OLM_CIPHER_BASE(&olm_pk_cipher_aes_sha256);

32
33
extern "C" {

34
35
36
37
38
39
40
41
42
43
44
45
struct OlmPkEncryption {
    OlmErrorCode last_error;
    _olm_curve25519_public_key recipient_key;
};

const char * olm_pk_encryption_last_error(
    OlmPkEncryption * encryption
) {
    auto error = encryption->last_error;
    return _olm_error_to_string(error);
}

46
size_t olm_pk_encryption_size(void) {
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
    return sizeof(OlmPkEncryption);
}

OlmPkEncryption *olm_pk_encryption(
    void * memory
) {
    olm::unset(memory, sizeof(OlmPkEncryption));
    return new(memory) OlmPkEncryption;
}

size_t olm_clear_pk_encryption(
    OlmPkEncryption *encryption
) {
    /* Clear the memory backing the encryption */
    olm::unset(encryption, sizeof(OlmPkEncryption));
    /* Initialise a fresh encryption object in case someone tries to use it */
    new(encryption) OlmPkEncryption();
    return sizeof(OlmPkEncryption);
}

size_t olm_pk_encryption_set_recipient_key (
    OlmPkEncryption *encryption,
    void const * key, size_t key_length
) {
    if (key_length < olm_pk_key_length()) {
        encryption->last_error =
Hubert Chathi's avatar
Hubert Chathi committed
73
            OlmErrorCode::OLM_INPUT_BUFFER_TOO_SMALL;
74
75
        return std::size_t(-1);
    }
76
77
78
79
80
    olm::decode_base64(
        (const uint8_t*)key,
        olm_pk_key_length(),
        (uint8_t *)encryption->recipient_key.public_key
    );
81
82
83
84
85
86
87
    return 0;
}

size_t olm_pk_ciphertext_length(
    OlmPkEncryption *encryption,
    size_t plaintext_length
) {
88
89
90
    return olm::encode_base64_length(
        _olm_cipher_aes_sha_256_ops.encrypt_ciphertext_length(olm_pk_cipher, plaintext_length)
    );
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
}

size_t olm_pk_mac_length(
    OlmPkEncryption *encryption
) {
    return olm::encode_base64_length(_olm_cipher_aes_sha_256_ops.mac_length(olm_pk_cipher));
}

size_t olm_pk_encrypt_random_length(
    OlmPkEncryption *encryption
) {
    return CURVE25519_KEY_LENGTH;
}

size_t olm_pk_encrypt(
    OlmPkEncryption *encryption,
    void const * plaintext, size_t plaintext_length,
    void * ciphertext, size_t ciphertext_length,
    void * mac, size_t mac_length,
    void * ephemeral_key, size_t ephemeral_key_size,
    void * random, size_t random_length
) {
    if (ciphertext_length
            < olm_pk_ciphertext_length(encryption, plaintext_length)
115
        || mac_length
116
            < _olm_cipher_aes_sha_256_ops.mac_length(olm_pk_cipher)
117
        || ephemeral_key_size
118
119
120
121
122
123
124
125
126
127
128
129
130
            < olm_pk_key_length()) {
        encryption->last_error =
            OlmErrorCode::OLM_OUTPUT_BUFFER_TOO_SMALL;
        return std::size_t(-1);
    }
    if (random_length < olm_pk_encrypt_random_length(encryption)) {
        encryption->last_error =
            OlmErrorCode::OLM_NOT_ENOUGH_RANDOM;
        return std::size_t(-1);
    }

    _olm_curve25519_key_pair ephemeral_keypair;
    _olm_crypto_curve25519_generate_key((uint8_t *) random, &ephemeral_keypair);
131
132
133
134
135
    olm::encode_base64(
        (const uint8_t *)ephemeral_keypair.public_key.public_key,
        CURVE25519_KEY_LENGTH,
        (uint8_t *)ephemeral_key
    );
136
137
138

    olm::SharedKey secret;
    _olm_crypto_curve25519_shared_secret(&ephemeral_keypair, &encryption->recipient_key, secret);
139
140
    size_t raw_ciphertext_length =
        _olm_cipher_aes_sha_256_ops.encrypt_ciphertext_length(olm_pk_cipher, plaintext_length);
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
    uint8_t *ciphertext_pos = (uint8_t *) ciphertext + ciphertext_length - raw_ciphertext_length;
    uint8_t raw_mac[MAC_LENGTH];
    size_t result = _olm_cipher_aes_sha_256_ops.encrypt(
        olm_pk_cipher,
        secret, sizeof(secret),
        (const uint8_t *) plaintext, plaintext_length,
        (uint8_t *) ciphertext_pos, raw_ciphertext_length,
        (uint8_t *) raw_mac, MAC_LENGTH
    );
    if (result != std::size_t(-1)) {
        olm::encode_base64(raw_mac, MAC_LENGTH, (uint8_t *)mac);
        olm::encode_base64(ciphertext_pos, raw_ciphertext_length, (uint8_t *)ciphertext);
    }
    return result;
}

struct OlmPkDecryption {
    OlmErrorCode last_error;
    _olm_curve25519_key_pair key_pair;
};

const char * olm_pk_decryption_last_error(
    OlmPkDecryption * decryption
) {
    auto error = decryption->last_error;
    return _olm_error_to_string(error);
}

169
size_t olm_pk_decryption_size(void) {
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
    return sizeof(OlmPkDecryption);
}

OlmPkDecryption *olm_pk_decryption(
    void * memory
) {
    olm::unset(memory, sizeof(OlmPkDecryption));
    return new(memory) OlmPkDecryption;
}

size_t olm_clear_pk_decryption(
    OlmPkDecryption *decryption
) {
    /* Clear the memory backing the decryption */
    olm::unset(decryption, sizeof(OlmPkDecryption));
    /* Initialise a fresh decryption object in case someone tries to use it */
    new(decryption) OlmPkDecryption();
    return sizeof(OlmPkDecryption);
}

190
size_t olm_pk_private_key_length(void) {
191
192
193
    return CURVE25519_KEY_LENGTH;
}

194
195
196
197
size_t olm_pk_generate_key_random_length(void) {
    return olm_pk_private_key_length();
}

198
size_t olm_pk_key_length(void) {
199
200
201
    return olm::encode_base64_length(CURVE25519_KEY_LENGTH);
}

202
size_t olm_pk_key_from_private(
203
204
    OlmPkDecryption * decryption,
    void * pubkey, size_t pubkey_length,
205
    void * privkey, size_t privkey_length
206
) {
David Baker's avatar
David Baker committed
207
    if (pubkey_length < olm_pk_key_length()) {
208
209
210
211
        decryption->last_error =
            OlmErrorCode::OLM_OUTPUT_BUFFER_TOO_SMALL;
        return std::size_t(-1);
    }
212
    if (privkey_length < olm_pk_private_key_length()) {
213
        decryption->last_error =
214
            OlmErrorCode::OLM_INPUT_BUFFER_TOO_SMALL;
215
216
217
        return std::size_t(-1);
    }

218
    _olm_crypto_curve25519_generate_key((uint8_t *) privkey, &decryption->key_pair);
219
220
221
222
223
    olm::encode_base64(
        (const uint8_t *)decryption->key_pair.public_key.public_key,
        CURVE25519_KEY_LENGTH,
        (uint8_t *)pubkey
    );
224
225
226
    return 0;
}

227
228
229
230
231
232
233
234
size_t olm_pk_generate_key(
    OlmPkDecryption * decryption,
    void * pubkey, size_t pubkey_length,
    void * privkey, size_t privkey_length
) {
    return olm_pk_key_from_private(decryption, pubkey, pubkey_length, privkey, privkey_length);
}

235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
namespace {
    static const std::uint32_t PK_DECRYPTION_PICKLE_VERSION = 1;

    static std::size_t pickle_length(
        OlmPkDecryption const & value
    ) {
        std::size_t length = 0;
        length += olm::pickle_length(PK_DECRYPTION_PICKLE_VERSION);
        length += olm::pickle_length(value.key_pair);
        return length;
    }


    static std::uint8_t * pickle(
        std::uint8_t * pos,
        OlmPkDecryption const & value
    ) {
        pos = olm::pickle(pos, PK_DECRYPTION_PICKLE_VERSION);
        pos = olm::pickle(pos, value.key_pair);
        return pos;
    }


    static std::uint8_t const * unpickle(
        std::uint8_t const * pos, std::uint8_t const * end,
        OlmPkDecryption & value
    ) {
        uint32_t pickle_version;
        pos = olm::unpickle(pos, end, pickle_version);

        switch (pickle_version) {
        case 1:
            break;

        default:
            value.last_error = OlmErrorCode::OLM_UNKNOWN_PICKLE_VERSION;
            return end;
        }

        pos = olm::unpickle(pos, end, value.key_pair);
        return pos;
    }
}

size_t olm_pickle_pk_decryption_length(
    OlmPkDecryption * decryption
) {
    return _olm_enc_output_length(pickle_length(*decryption));
}

size_t olm_pickle_pk_decryption(
    OlmPkDecryption * decryption,
    void const * key, size_t key_length,
    void *pickled, size_t pickled_length
) {
    OlmPkDecryption & object = *decryption;
    std::size_t raw_length = pickle_length(object);
    if (pickled_length < _olm_enc_output_length(raw_length)) {
        object.last_error = OlmErrorCode::OLM_OUTPUT_BUFFER_TOO_SMALL;
        return std::size_t(-1);
    }
    pickle(_olm_enc_output_pos(reinterpret_cast<std::uint8_t *>(pickled), raw_length), object);
297
298
299
300
    return _olm_enc_output(
        reinterpret_cast<std::uint8_t const *>(key), key_length,
        reinterpret_cast<std::uint8_t *>(pickled), raw_length
    );
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
}

size_t olm_unpickle_pk_decryption(
    OlmPkDecryption * decryption,
    void const * key, size_t key_length,
    void *pickled, size_t pickled_length,
    void *pubkey, size_t pubkey_length
) {
    OlmPkDecryption & object = *decryption;
    if (pubkey != NULL && pubkey_length < olm_pk_key_length()) {
        object.last_error = OlmErrorCode::OLM_OUTPUT_BUFFER_TOO_SMALL;
        return std::size_t(-1);
    }
    std::uint8_t * const pos = reinterpret_cast<std::uint8_t *>(pickled);
    std::size_t raw_length = _olm_enc_input(
316
317
        reinterpret_cast<std::uint8_t const *>(key), key_length,
        pos, pickled_length, &object.last_error
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
    );
    if (raw_length == std::size_t(-1)) {
        return std::size_t(-1);
    }
    std::uint8_t * const end = pos + raw_length;
    /* On success unpickle will return (pos + raw_length). If unpickling
     * terminates too soon then it will return a pointer before
     * (pos + raw_length). On error unpickle will return (pos + raw_length + 1).
     */
    if (end != unpickle(pos, end + 1, object)) {
        if (object.last_error == OlmErrorCode::OLM_SUCCESS) {
            object.last_error = OlmErrorCode::OLM_CORRUPTED_PICKLE;
        }
        return std::size_t(-1);
    }
    if (pubkey != NULL) {
334
335
336
337
338
        olm::encode_base64(
            (const uint8_t *)object.key_pair.public_key.public_key,
            CURVE25519_KEY_LENGTH,
            (uint8_t *)pubkey
        );
339
340
341
342
    }
    return pickled_length;
}

343
344
345
346
size_t olm_pk_max_plaintext_length(
    OlmPkDecryption * decryption,
    size_t ciphertext_length
) {
347
348
349
    return _olm_cipher_aes_sha_256_ops.decrypt_max_plaintext_length(
        olm_pk_cipher, olm::decode_base64_length(ciphertext_length)
    );
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
}

size_t olm_pk_decrypt(
    OlmPkDecryption * decryption,
    void const * ephemeral_key, size_t ephemeral_key_length,
    void const * mac, size_t mac_length,
    void * ciphertext, size_t ciphertext_length,
    void * plaintext, size_t max_plaintext_length
) {
    if (max_plaintext_length
            < olm_pk_max_plaintext_length(decryption, ciphertext_length)) {
        decryption->last_error =
            OlmErrorCode::OLM_OUTPUT_BUFFER_TOO_SMALL;
        return std::size_t(-1);
    }

    struct _olm_curve25519_public_key ephemeral;
367
368
369
370
    olm::decode_base64(
        (const uint8_t*)ephemeral_key, ephemeral_key_length,
        (uint8_t *)ephemeral.public_key
    );
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
    olm::SharedKey secret;
    _olm_crypto_curve25519_shared_secret(&decryption->key_pair, &ephemeral, secret);
    uint8_t raw_mac[MAC_LENGTH];
    olm::decode_base64((const uint8_t*)mac, olm::encode_base64_length(MAC_LENGTH), raw_mac);
    size_t raw_ciphertext_length = olm::decode_base64_length(ciphertext_length);
    olm::decode_base64((const uint8_t *)ciphertext, ciphertext_length, (uint8_t *)ciphertext);
    size_t result = _olm_cipher_aes_sha_256_ops.decrypt(
        olm_pk_cipher,
        secret, sizeof(secret),
        (uint8_t *) raw_mac, MAC_LENGTH,
        (const uint8_t *) ciphertext, raw_ciphertext_length,
        (uint8_t *) plaintext, max_plaintext_length
    );
    if (result == std::size_t(-1)) {
        // we already checked the buffer sizes, so the only error that decrypt
        // will return is if the MAC is incorrect
        decryption->last_error =
            OlmErrorCode::OLM_BAD_MESSAGE_MAC;
        return std::size_t(-1);
    } else {
        return result;
    }
}

395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
size_t olm_pk_get_private_key(
    OlmPkDecryption * decryption,
    void *private_key, size_t private_key_length
) {
    if (private_key_length < olm_pk_private_key_length()) {
        decryption->last_error =
            OlmErrorCode::OLM_OUTPUT_BUFFER_TOO_SMALL;
        return std::size_t(-1);
    }
    std::memcpy(
        private_key,
        decryption->key_pair.private_key.private_key,
        olm_pk_private_key_length()
    );
    return olm_pk_private_key_length();
}

412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
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
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
struct OlmPkSigning {
    OlmErrorCode last_error;
    _olm_ed25519_key_pair key_pair;
};

size_t olm_pk_signing_size(void) {
    return sizeof(OlmPkSigning);
}

OlmPkSigning *olm_pk_signing(void * memory) {
    olm::unset(memory, sizeof(OlmPkSigning));
    return new(memory) OlmPkSigning;
}

const char * olm_pk_signing_last_error(OlmPkSigning * sign) {
    auto error = sign->last_error;
    return _olm_error_to_string(error);
}

size_t olm_clear_pk_signing(OlmPkSigning *sign) {
    /* Clear the memory backing the signing */
    olm::unset(sign, sizeof(OlmPkSigning));
    /* Initialise a fresh signing object in case someone tries to use it */
    new(sign) OlmPkSigning();
    return sizeof(OlmPkSigning);
}

size_t olm_pk_sign_seed_length(void) {
    return ED25519_RANDOM_LENGTH;
}

size_t olm_pk_sign_public_key_length(void) {
    return olm::encode_base64_length(ED25519_PUBLIC_KEY_LENGTH);
}

size_t olm_pk_signing_key_from_seed(
    OlmPkSigning * signing,
    void * pubkey, size_t pubkey_length,
    void * seed, size_t seed_length
) {
    if (pubkey_length < olm_pk_sign_public_key_length()) {
        signing->last_error =
            OlmErrorCode::OLM_OUTPUT_BUFFER_TOO_SMALL;
        return std::size_t(-1);
    }
    if (seed_length < olm_pk_sign_seed_length()) {
        signing->last_error =
            OlmErrorCode::OLM_INPUT_BUFFER_TOO_SMALL;
        return std::size_t(-1);
    }

    _olm_crypto_ed25519_generate_key((uint8_t *) seed, &signing->key_pair);
    olm::encode_base64(
        (const uint8_t *)signing->key_pair.public_key.public_key,
        ED25519_PUBLIC_KEY_LENGTH,
        (uint8_t *)pubkey
    );
    return 0;
}

size_t olm_pk_signature_length() {
    return olm::encode_base64_length(ED25519_SIGNATURE_LENGTH);
}

size_t olm_pk_sign(
    OlmPkSigning *signing,
    uint8_t const * message, size_t message_length,
    uint8_t * signature, size_t signature_length
) {
    if (signature_length < olm_pk_signature_length()) {
        signing->last_error = OlmErrorCode::OLM_OUTPUT_BUFFER_TOO_SMALL;
        return std::size_t(-1);
    }
    uint8_t *raw_sig = signature + olm_pk_signature_length() - ED25519_SIGNATURE_LENGTH;
    _olm_crypto_ed25519_sign(
        &signing->key_pair,
        message, message_length, raw_sig
    );
    olm::encode_base64(raw_sig, ED25519_SIGNATURE_LENGTH, signature);
    return olm_pk_signature_length();
}

494
}