aboutsummaryrefslogtreecommitdiff
path: root/src/login/mod.rs
blob: 6c948cc79f83e6cd957e44479afe0ebce986d569 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
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
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
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
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
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
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
pub mod ldap_provider;
pub mod static_provider;

use std::collections::BTreeMap;
use std::sync::Arc;

use anyhow::{anyhow, bail, Context, Result};
use async_trait::async_trait;
use k2v_client::{
    BatchInsertOp, BatchReadOp, CausalValue, CausalityToken, Filter, K2vClient, K2vValue,
};
use rand::prelude::*;
use rusoto_core::HttpClient;
use rusoto_credential::{AwsCredentials, StaticProvider};
use rusoto_s3::S3Client;

use crate::cryptoblob::*;
use crate::storage::*;

/// The trait LoginProvider defines the interface for a login provider that allows
/// to retrieve storage and cryptographic credentials for access to a user account
/// from their username and password.
#[async_trait]
pub trait LoginProvider {
    /// The login method takes an account's password as an input to decypher
    /// decryption keys and obtain full access to the user's account.
    async fn login(&self, username: &str, password: &str) -> Result<Credentials>;
    /// The public_login method takes an account's email address and returns
    /// public credentials for adding mails to the user's inbox.
    async fn public_login(&self, email: &str) -> Result<PublicCredentials>;
}

/// ArcLoginProvider is simply an alias on a structure that is used
/// in many places in the code
pub type ArcLoginProvider = Arc<dyn LoginProvider + Send + Sync>;

/// The struct Credentials represent all of the necessary information to interact
/// with a user account's data after they are logged in.
#[derive(Clone, Debug)]
pub struct Credentials {
    /// The storage credentials are used to authenticate access to the underlying storage (S3, K2V)
    pub storage: Engine,
    /// The cryptographic keys are used to encrypt and decrypt data stored in S3 and K2V
    pub keys: CryptoKeys,
}

#[derive(Clone, Debug)]
pub struct PublicCredentials {
    /// The storage credentials are used to authenticate access to the underlying storage (S3, K2V)
    pub storage: StorageCredentials,
    pub public_key: PublicKey,
}

/// The struct StorageCredentials contains access key to an S3 and K2V bucket
#[derive(Clone, Debug, Hash, PartialEq, Eq)]
pub struct StorageCredentials {
    pub s3_region: Region,
    pub k2v_region: Region,

    pub aws_access_key_id: String,
    pub aws_secret_access_key: String,
    pub bucket: String,
}

/// The struct UserSecrets represents intermediary secrets that are mixed in with the user's
/// password when decrypting the cryptographic keys that are stored in their bucket.
/// These secrets should be stored somewhere else (e.g. in the LDAP server or in the
/// local config file), as an additionnal authentification factor so that the password
/// isn't enough just alone to decrypt the content of a user's bucket.
pub struct UserSecrets {
    /// The main user secret that will be used to encrypt keys when a new password is added
    pub user_secret: String,
    /// Alternative user secrets that will be tried when decrypting keys that were encrypted
    /// with old passwords
    pub alternate_user_secrets: Vec<String>,
}

/// The struct CryptoKeys contains the cryptographic keys used to encrypt and decrypt
/// data in a user's mailbox.
#[derive(Clone, Debug)]
pub struct CryptoKeys {
    /// Master key for symmetric encryption of mailbox data
    pub master: Key,
    /// Public/private keypair for encryption of incomming emails (secret part)
    pub secret: SecretKey,
    /// Public/private keypair for encryption of incomming emails (public part)
    pub public: PublicKey,
}

/// A custom S3 region, composed of a region name and endpoint.
/// We use this instead of rusoto_signature::Region so that we can
/// derive Hash and Eq
#[derive(Clone, Debug, Hash, PartialEq, Eq)]
pub struct Region {
    pub name: String,
    pub endpoint: String,
}

impl Region {
    pub fn as_rusoto_region(&self) -> rusoto_signature::Region {
        rusoto_signature::Region::Custom {
            name: self.name.clone(),
            endpoint: self.endpoint.clone(),
        }
    }
}

// ----


impl Credentials {
    pub fn k2v_client(&self) -> Result<RowStore, Error> {
        self.storage.row.row_store()
    }
    pub fn s3_client(&self) -> Result<S3Client> {
        self.storage.s3_client()
    }
    pub fn bucket(&self) -> &str {
        self.storage.bucket.as_str()
    }
}

impl StorageCredentials {
    pub fn k2v_client(&self) -> Result<K2vClient> {
        let aws_creds = AwsCredentials::new(
            self.aws_access_key_id.clone(),
            self.aws_secret_access_key.clone(),
            None,
            None,
        );

        Ok(K2vClient::new(
            self.k2v_region.as_rusoto_region(),
            self.bucket.clone(),
            aws_creds,
            None,
        )?)
    }

    pub fn s3_client(&self) -> Result<S3Client> {
        let aws_creds_provider = StaticProvider::new_minimal(
            self.aws_access_key_id.clone(),
            self.aws_secret_access_key.clone(),
        );

        let connector = hyper_rustls::HttpsConnectorBuilder::new()
            .with_native_roots()
            .https_or_http()
            .enable_http1()
            .enable_http2()
            .build();
        let client = HttpClient::from_connector(connector);

        Ok(S3Client::new_with(
            client,
            aws_creds_provider,
            self.s3_region.as_rusoto_region(),
        ))
    }
}

impl CryptoKeys {
    pub async fn init(
        storage: &StorageCredentials,
        user_secrets: &UserSecrets,
        password: &str,
    ) -> Result<Self> {
        // Check that salt and public don't exist already
        let k2v = storage.k2v_client()?;
        let (salt_ct, public_ct) = Self::check_uninitialized(&k2v).await?;

        // Generate salt for password identifiers
        let mut ident_salt = [0u8; 32];
        thread_rng().fill(&mut ident_salt);

        // Generate (public, private) key pair and master key
        let (public, secret) = gen_keypair();
        let master = gen_key();
        let keys = CryptoKeys {
            master,
            secret,
            public,
        };

        // Generate short password digest (= password identity)
        let ident = argon2_kdf(&ident_salt, password.as_bytes(), 16)?;

        // Generate salt for KDF
        let mut kdf_salt = [0u8; 32];
        thread_rng().fill(&mut kdf_salt);

        // Calculate key for password secret box
        let password_key = user_secrets.derive_password_key(&kdf_salt, password)?;

        // Seal a secret box that contains our crypto keys
        let password_sealed = seal(&keys.serialize(), &password_key)?;

        let password_sortkey = format!("password:{}", hex::encode(&ident));
        let password_blob = [&kdf_salt[..], &password_sealed].concat();

        // Write values to storage
        k2v.insert_batch(&[
            k2v_insert_single_key("keys", "salt", salt_ct, ident_salt),
            k2v_insert_single_key("keys", "public", public_ct, keys.public),
            k2v_insert_single_key("keys", &password_sortkey, None, &password_blob),
        ])
        .await
        .context("InsertBatch for salt, public, and password")?;

        Ok(keys)
    }

    pub async fn init_without_password(
        storage: &StorageCredentials,
        master: &Key,
        secret: &SecretKey,
    ) -> Result<Self> {
        // Check that salt and public don't exist already
        let k2v = storage.k2v_client()?;
        let (salt_ct, public_ct) = Self::check_uninitialized(&k2v).await?;

        // Generate salt for password identifiers
        let mut ident_salt = [0u8; 32];
        thread_rng().fill(&mut ident_salt);

        // Create CryptoKeys struct from given keys
        let public = secret.public_key();
        let keys = CryptoKeys {
            master: master.clone(),
            secret: secret.clone(),
            public,
        };

        // Write values to storage
        k2v.insert_batch(&[
            k2v_insert_single_key("keys", "salt", salt_ct, ident_salt),
            k2v_insert_single_key("keys", "public", public_ct, keys.public),
        ])
        .await
        .context("InsertBatch for salt and public")?;

        Ok(keys)
    }

    pub async fn open(
        storage: &StorageCredentials,
        user_secrets: &UserSecrets,
        password: &str,
    ) -> Result<Self> {
        let k2v = storage.k2v_client()?;
        let (ident_salt, expected_public) = Self::load_salt_and_public(&k2v).await?;

        // Generate short password digest (= password identity)
        let ident = argon2_kdf(&ident_salt, password.as_bytes(), 16)?;

        // Lookup password blob
        let password_sortkey = format!("password:{}", hex::encode(&ident));

        let password_blob = {
            let mut val = match k2v.read_item("keys", &password_sortkey).await {
                Err(k2v_client::Error::NotFound) => {
                    bail!("invalid password")
                }
                x => x?,
            };
            if val.value.len() != 1 {
                bail!("multiple values for password in storage");
            }
            match val.value.pop().unwrap() {
                K2vValue::Value(v) => v,
                K2vValue::Tombstone => bail!("invalid password"),
            }
        };

        // Try to open blob
        let kdf_salt = &password_blob[..32];
        let password_openned =
            user_secrets.try_open_encrypted_keys(kdf_salt, password, &password_blob[32..])?;

        let keys = Self::deserialize(&password_openned)?;
        if keys.public != expected_public {
            bail!("Password public key doesn't match stored public key");
        }

        Ok(keys)
    }

    pub async fn open_without_password(
        storage: &StorageCredentials,
        master: &Key,
        secret: &SecretKey,
    ) -> Result<Self> {
        let k2v = storage.k2v_client()?;
        let (_ident_salt, expected_public) = Self::load_salt_and_public(&k2v).await?;

        // Create CryptoKeys struct from given keys
        let public = secret.public_key();
        let keys = CryptoKeys {
            master: master.clone(),
            secret: secret.clone(),
            public,
        };

        // Check public key matches
        if keys.public != expected_public {
            bail!("Given public key doesn't match stored public key");
        }

        Ok(keys)
    }

    pub async fn add_password(
        &self,
        storage: &StorageCredentials,
        user_secrets: &UserSecrets,
        password: &str,
    ) -> Result<()> {
        let k2v = storage.k2v_client()?;
        let (ident_salt, _public) = Self::load_salt_and_public(&k2v).await?;

        // Generate short password digest (= password identity)
        let ident = argon2_kdf(&ident_salt, password.as_bytes(), 16)?;

        // Generate salt for KDF
        let mut kdf_salt = [0u8; 32];
        thread_rng().fill(&mut kdf_salt);

        // Calculate key for password secret box
        let password_key = user_secrets.derive_password_key(&kdf_salt, password)?;

        // Seal a secret box that contains our crypto keys
        let password_sealed = seal(&self.serialize(), &password_key)?;

        let password_sortkey = format!("password:{}", hex::encode(&ident));
        let password_blob = [&kdf_salt[..], &password_sealed].concat();

        // List existing passwords to overwrite existing entry if necessary
        let ct = match k2v.read_item("keys", &password_sortkey).await {
            Err(k2v_client::Error::NotFound) => None,
            v => {
                let entry = v?;
                if entry.value.iter().any(|x| matches!(x, K2vValue::Value(_))) {
                    bail!("password already exists");
                }
                Some(entry.causality)
            }
        };

        // Write values to storage
        k2v.insert_batch(&[k2v_insert_single_key(
            "keys",
            &password_sortkey,
            ct,
            &password_blob,
        )])
        .await
        .context("InsertBatch for new password")?;

        Ok(())
    }

    pub async fn delete_password(
        storage: &StorageCredentials,
        password: &str,
        allow_delete_all: bool,
    ) -> Result<()> {
        let k2v = storage.k2v_client()?;
        let (ident_salt, _public) = Self::load_salt_and_public(&k2v).await?;

        // Generate short password digest (= password identity)
        let ident = argon2_kdf(&ident_salt, password.as_bytes(), 16)?;
        let password_sortkey = format!("password:{}", hex::encode(&ident));

        // List existing passwords
        let existing_passwords = Self::list_existing_passwords(&k2v).await?;

        // Check password is there
        let pw = existing_passwords
            .get(&password_sortkey)
            .ok_or(anyhow!("password does not exist"))?;

        if !allow_delete_all && existing_passwords.len() < 2 {
            bail!("No other password exists, not deleting last password.");
        }

        k2v.delete_item("keys", &password_sortkey, pw.causality.clone())
            .await
            .context("DeleteItem for password")?;

        Ok(())
    }

    // ---- STORAGE UTIL ----

    async fn check_uninitialized(
        k2v: &K2vClient,
    ) -> Result<(Option<CausalityToken>, Option<CausalityToken>)> {
        let params = k2v
            .read_batch(&[
                k2v_read_single_key("keys", "salt", true),
                k2v_read_single_key("keys", "public", true),
            ])
            .await
            .context("ReadBatch for salt and public in check_uninitialized")?;
        if params.len() != 2 {
            bail!(
                "Invalid response from k2v storage: {:?} (expected two items)",
                params
            );
        }
        if params[0].items.len() > 1 || params[1].items.len() > 1 {
            bail!(
                "invalid response from k2v storage: {:?} (several items in single_item read)",
                params
            );
        }

        let salt_ct = match params[0].items.iter().next() {
            None => None,
            Some((_, CausalValue { causality, value })) => {
                if value.iter().any(|x| matches!(x, K2vValue::Value(_))) {
                    bail!("key storage already initialized");
                }
                Some(causality.clone())
            }
        };

        let public_ct = match params[1].items.iter().next() {
            None => None,
            Some((_, CausalValue { causality, value })) => {
                if value.iter().any(|x| matches!(x, K2vValue::Value(_))) {
                    bail!("key storage already initialized");
                }
                Some(causality.clone())
            }
        };

        Ok((salt_ct, public_ct))
    }

    pub async fn load_salt_and_public(k2v: &K2vClient) -> Result<([u8; 32], PublicKey)> {
        let mut params = k2v
            .read_batch(&[
                k2v_read_single_key("keys", "salt", false),
                k2v_read_single_key("keys", "public", false),
            ])
            .await
            .context("ReadBatch for salt and public in load_salt_and_public")?;
        if params.len() != 2 {
            bail!(
                "Invalid response from k2v storage: {:?} (expected two items)",
                params
            );
        }
        if params[0].items.len() != 1 || params[1].items.len() != 1 {
            bail!("cryptographic keys not initialized for user");
        }

        // Retrieve salt from given response
        let salt_vals = &mut params[0].items.iter_mut().next().unwrap().1.value;
        if salt_vals.len() != 1 {
            bail!("Multiple values for `salt`");
        }
        let salt: Vec<u8> = match &mut salt_vals[0] {
            K2vValue::Value(v) => std::mem::take(v),
            K2vValue::Tombstone => bail!("salt is a tombstone"),
        };
        if salt.len() != 32 {
            bail!("`salt` is not 32 bytes long");
        }
        let mut salt_constlen = [0u8; 32];
        salt_constlen.copy_from_slice(&salt);

        // Retrieve public from given response
        let public_vals = &mut params[1].items.iter_mut().next().unwrap().1.value;
        if public_vals.len() != 1 {
            bail!("Multiple values for `public`");
        }
        let public: Vec<u8> = match &mut public_vals[0] {
            K2vValue::Value(v) => std::mem::take(v),
            K2vValue::Tombstone => bail!("public is a tombstone"),
        };
        let public = PublicKey::from_slice(&public).ok_or(anyhow!("Invalid public key length"))?;

        Ok((salt_constlen, public))
    }

    async fn list_existing_passwords(k2v: &K2vClient) -> Result<BTreeMap<String, CausalValue>> {
        let mut res = k2v
            .read_batch(&[BatchReadOp {
                partition_key: "keys",
                filter: Filter {
                    start: None,
                    end: None,
                    prefix: Some("password:"),
                    limit: None,
                    reverse: false,
                },
                conflicts_only: false,
                tombstones: false,
                single_item: false,
            }])
            .await
            .context("ReadBatch for prefix password: in list_existing_passwords")?;
        if res.len() != 1 {
            bail!("unexpected k2v result: {:?}, expected one item", res);
        }
        Ok(res.pop().unwrap().items)
    }

    fn serialize(&self) -> [u8; 64] {
        let mut res = [0u8; 64];
        res[..32].copy_from_slice(self.master.as_ref());
        res[32..].copy_from_slice(self.secret.as_ref());
        res
    }

    fn deserialize(bytes: &[u8]) -> Result<Self> {
        if bytes.len() != 64 {
            bail!("Invalid length: {}, expected 64", bytes.len());
        }
        let master = Key::from_slice(&bytes[..32]).unwrap();
        let secret = SecretKey::from_slice(&bytes[32..]).unwrap();
        let public = secret.public_key();
        Ok(Self {
            master,
            secret,
            public,
        })
    }
}

impl UserSecrets {
    fn derive_password_key_with(user_secret: &str, kdf_salt: &[u8], password: &str) -> Result<Key> {
        let tmp = format!("{}\n\n{}", user_secret, password);
        Ok(Key::from_slice(&argon2_kdf(kdf_salt, tmp.as_bytes(), 32)?).unwrap())
    }

    fn derive_password_key(&self, kdf_salt: &[u8], password: &str) -> Result<Key> {
        Self::derive_password_key_with(&self.user_secret, kdf_salt, password)
    }

    fn try_open_encrypted_keys(
        &self,
        kdf_salt: &[u8],
        password: &str,
        encrypted_keys: &[u8],
    ) -> Result<Vec<u8>> {
        let secrets_to_try =
            std::iter::once(&self.user_secret).chain(self.alternate_user_secrets.iter());
        for user_secret in secrets_to_try {
            let password_key = Self::derive_password_key_with(user_secret, kdf_salt, password)?;
            if let Ok(res) = open(encrypted_keys, &password_key) {
                return Ok(res);
            }
        }
        bail!("Unable to decrypt password blob.");
    }
}

// ---- UTIL ----

pub fn argon2_kdf(salt: &[u8], password: &[u8], output_len: usize) -> Result<Vec<u8>> {
    use argon2::{Algorithm, Argon2, ParamsBuilder, PasswordHasher, Version};

    let mut params = ParamsBuilder::new();
    params
        .output_len(output_len)
        .map_err(|e| anyhow!("Invalid output length: {}", e))?;

    let params = params
        .params()
        .map_err(|e| anyhow!("Invalid argon2 params: {}", e))?;
    let argon2 = Argon2::new(Algorithm::default(), Version::default(), params);

    let salt = base64::encode_config(salt, base64::STANDARD_NO_PAD);
    let hash = argon2
        .hash_password(password, &salt)
        .map_err(|e| anyhow!("Unable to hash: {}", e))?;

    let hash = hash.hash.ok_or(anyhow!("Missing output"))?;
    assert!(hash.len() == output_len);
    Ok(hash.as_bytes().to_vec())
}

pub fn k2v_read_single_key<'a>(
    partition_key: &'a str,
    sort_key: &'a str,
    tombstones: bool,
) -> BatchReadOp<'a> {
    BatchReadOp {
        partition_key,
        filter: Filter {
            start: Some(sort_key),
            end: None,
            prefix: None,
            limit: None,
            reverse: false,
        },
        conflicts_only: false,
        tombstones,
        single_item: true,
    }
}

pub fn k2v_insert_single_key<'a>(
    partition_key: &'a str,
    sort_key: &'a str,
    causality: Option<CausalityToken>,
    value: impl AsRef<[u8]>,
) -> BatchInsertOp<'a> {
    BatchInsertOp {
        partition_key,
        sort_key,
        causality,
        value: K2vValue::Value(value.as_ref().to_vec()),
    }
}