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
use crate::crypto::cipher::{
    make_tls12_aad, AeadKey, Iv, KeyBlockShape, MessageDecrypter, MessageEncrypter, Nonce,
    Tls12AeadAlgorithm, UnsupportedOperationError, NONCE_LEN,
};
use crate::crypto::tls12::PrfUsingHmac;
use crate::crypto::KeyExchangeAlgorithm;
use crate::enums::{CipherSuite, SignatureScheme};
use crate::error::Error;
use crate::msgs::fragmenter::MAX_FRAGMENT_LEN;
use crate::msgs::message::{BorrowedPlainMessage, OpaqueMessage, PlainMessage};
use crate::suites::{CipherSuiteCommon, ConnectionTrafficSecrets, SupportedCipherSuite};
use crate::tls12::Tls12CipherSuite;

use alloc::boxed::Box;
use alloc::vec::Vec;

use super::ring_like::aead;

/// The TLS1.2 ciphersuite TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256.
pub static TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256: SupportedCipherSuite =
    SupportedCipherSuite::Tls12(&Tls12CipherSuite {
        common: CipherSuiteCommon {
            suite: CipherSuite::TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
            hash_provider: &super::hash::SHA256,
            confidentiality_limit: u64::MAX,
            integrity_limit: 1 << 36,
        },
        kx: KeyExchangeAlgorithm::ECDHE,
        sign: TLS12_ECDSA_SCHEMES,
        aead_alg: &ChaCha20Poly1305,
        prf_provider: &PrfUsingHmac(&super::hmac::HMAC_SHA256),
    });

/// The TLS1.2 ciphersuite TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
pub static TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256: SupportedCipherSuite =
    SupportedCipherSuite::Tls12(&Tls12CipherSuite {
        common: CipherSuiteCommon {
            suite: CipherSuite::TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
            hash_provider: &super::hash::SHA256,
            confidentiality_limit: u64::MAX,
            integrity_limit: 1 << 36,
        },
        kx: KeyExchangeAlgorithm::ECDHE,
        sign: TLS12_RSA_SCHEMES,
        aead_alg: &ChaCha20Poly1305,
        prf_provider: &PrfUsingHmac(&super::hmac::HMAC_SHA256),
    });

/// The TLS1.2 ciphersuite TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
pub static TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256: SupportedCipherSuite =
    SupportedCipherSuite::Tls12(&Tls12CipherSuite {
        common: CipherSuiteCommon {
            suite: CipherSuite::TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
            hash_provider: &super::hash::SHA256,
            confidentiality_limit: 1 << 23,
            integrity_limit: 1 << 52,
        },
        kx: KeyExchangeAlgorithm::ECDHE,
        sign: TLS12_RSA_SCHEMES,
        aead_alg: &AES128_GCM,
        prf_provider: &PrfUsingHmac(&super::hmac::HMAC_SHA256),
    });

/// The TLS1.2 ciphersuite TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
pub static TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384: SupportedCipherSuite =
    SupportedCipherSuite::Tls12(&Tls12CipherSuite {
        common: CipherSuiteCommon {
            suite: CipherSuite::TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
            hash_provider: &super::hash::SHA384,
            confidentiality_limit: 1 << 23,
            integrity_limit: 1 << 52,
        },
        kx: KeyExchangeAlgorithm::ECDHE,
        sign: TLS12_RSA_SCHEMES,
        aead_alg: &AES256_GCM,
        prf_provider: &PrfUsingHmac(&super::hmac::HMAC_SHA384),
    });

/// The TLS1.2 ciphersuite TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
pub static TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256: SupportedCipherSuite =
    SupportedCipherSuite::Tls12(&Tls12CipherSuite {
        common: CipherSuiteCommon {
            suite: CipherSuite::TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
            hash_provider: &super::hash::SHA256,
            confidentiality_limit: 1 << 23,
            integrity_limit: 1 << 52,
        },
        kx: KeyExchangeAlgorithm::ECDHE,
        sign: TLS12_ECDSA_SCHEMES,
        aead_alg: &AES128_GCM,
        prf_provider: &PrfUsingHmac(&super::hmac::HMAC_SHA256),
    });

/// The TLS1.2 ciphersuite TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
pub static TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384: SupportedCipherSuite =
    SupportedCipherSuite::Tls12(&Tls12CipherSuite {
        common: CipherSuiteCommon {
            suite: CipherSuite::TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
            hash_provider: &super::hash::SHA384,
            confidentiality_limit: 1 << 23,
            integrity_limit: 1 << 52,
        },
        kx: KeyExchangeAlgorithm::ECDHE,
        sign: TLS12_ECDSA_SCHEMES,
        aead_alg: &AES256_GCM,
        prf_provider: &PrfUsingHmac(&super::hmac::HMAC_SHA384),
    });

static TLS12_ECDSA_SCHEMES: &[SignatureScheme] = &[
    SignatureScheme::ED25519,
    SignatureScheme::ECDSA_NISTP521_SHA512,
    SignatureScheme::ECDSA_NISTP384_SHA384,
    SignatureScheme::ECDSA_NISTP256_SHA256,
];

static TLS12_RSA_SCHEMES: &[SignatureScheme] = &[
    SignatureScheme::RSA_PSS_SHA512,
    SignatureScheme::RSA_PSS_SHA384,
    SignatureScheme::RSA_PSS_SHA256,
    SignatureScheme::RSA_PKCS1_SHA512,
    SignatureScheme::RSA_PKCS1_SHA384,
    SignatureScheme::RSA_PKCS1_SHA256,
];

pub(crate) static AES128_GCM: GcmAlgorithm = GcmAlgorithm(&aead::AES_128_GCM);
pub(crate) static AES256_GCM: GcmAlgorithm = GcmAlgorithm(&aead::AES_256_GCM);

pub(crate) struct GcmAlgorithm(&'static aead::Algorithm);

impl Tls12AeadAlgorithm for GcmAlgorithm {
    fn decrypter(&self, dec_key: AeadKey, dec_iv: &[u8]) -> Box<dyn MessageDecrypter> {
        let dec_key =
            aead::LessSafeKey::new(aead::UnboundKey::new(self.0, dec_key.as_ref()).unwrap());

        let mut ret = GcmMessageDecrypter {
            dec_key,
            dec_salt: [0u8; 4],
        };

        debug_assert_eq!(dec_iv.len(), 4);
        ret.dec_salt.copy_from_slice(dec_iv);
        Box::new(ret)
    }

    fn encrypter(
        &self,
        enc_key: AeadKey,
        write_iv: &[u8],
        explicit: &[u8],
    ) -> Box<dyn MessageEncrypter> {
        let enc_key =
            aead::LessSafeKey::new(aead::UnboundKey::new(self.0, enc_key.as_ref()).unwrap());
        let iv = gcm_iv(write_iv, explicit);
        Box::new(GcmMessageEncrypter { enc_key, iv })
    }

    fn key_block_shape(&self) -> KeyBlockShape {
        KeyBlockShape {
            enc_key_len: self.0.key_len(),
            fixed_iv_len: 4,
            explicit_nonce_len: 8,
        }
    }

    fn extract_keys(
        &self,
        key: AeadKey,
        write_iv: &[u8],
        explicit: &[u8],
    ) -> Result<ConnectionTrafficSecrets, UnsupportedOperationError> {
        let iv = gcm_iv(write_iv, explicit);
        Ok(match self.0.key_len() {
            16 => ConnectionTrafficSecrets::Aes128Gcm { key, iv },
            32 => ConnectionTrafficSecrets::Aes256Gcm { key, iv },
            _ => unreachable!(),
        })
    }
}

pub(crate) struct ChaCha20Poly1305;

impl Tls12AeadAlgorithm for ChaCha20Poly1305 {
    fn decrypter(&self, dec_key: AeadKey, iv: &[u8]) -> Box<dyn MessageDecrypter> {
        let dec_key = aead::LessSafeKey::new(
            aead::UnboundKey::new(&aead::CHACHA20_POLY1305, dec_key.as_ref()).unwrap(),
        );
        Box::new(ChaCha20Poly1305MessageDecrypter {
            dec_key,
            dec_offset: Iv::copy(iv),
        })
    }

    fn encrypter(&self, enc_key: AeadKey, enc_iv: &[u8], _: &[u8]) -> Box<dyn MessageEncrypter> {
        let enc_key = aead::LessSafeKey::new(
            aead::UnboundKey::new(&aead::CHACHA20_POLY1305, enc_key.as_ref()).unwrap(),
        );
        Box::new(ChaCha20Poly1305MessageEncrypter {
            enc_key,
            enc_offset: Iv::copy(enc_iv),
        })
    }

    fn key_block_shape(&self) -> KeyBlockShape {
        KeyBlockShape {
            enc_key_len: 32,
            fixed_iv_len: 12,
            explicit_nonce_len: 0,
        }
    }

    fn extract_keys(
        &self,
        key: AeadKey,
        iv: &[u8],
        _explicit: &[u8],
    ) -> Result<ConnectionTrafficSecrets, UnsupportedOperationError> {
        // This should always be true because KeyBlockShape and the Iv nonce len are in agreement.
        debug_assert_eq!(aead::NONCE_LEN, iv.len());
        Ok(ConnectionTrafficSecrets::Chacha20Poly1305 {
            key,
            iv: Iv::new(iv[..].try_into().unwrap()),
        })
    }
}

/// A `MessageEncrypter` for AES-GCM AEAD ciphersuites. TLS 1.2 only.
struct GcmMessageEncrypter {
    enc_key: aead::LessSafeKey,
    iv: Iv,
}

/// A `MessageDecrypter` for AES-GCM AEAD ciphersuites.  TLS1.2 only.
struct GcmMessageDecrypter {
    dec_key: aead::LessSafeKey,
    dec_salt: [u8; 4],
}

const GCM_EXPLICIT_NONCE_LEN: usize = 8;
const GCM_OVERHEAD: usize = GCM_EXPLICIT_NONCE_LEN + 16;

impl MessageDecrypter for GcmMessageDecrypter {
    fn decrypt(&mut self, mut msg: OpaqueMessage, seq: u64) -> Result<PlainMessage, Error> {
        let payload = msg.payload();
        if payload.len() < GCM_OVERHEAD {
            return Err(Error::DecryptError);
        }

        let nonce = {
            let mut nonce = [0u8; 12];
            nonce[..4].copy_from_slice(&self.dec_salt);
            nonce[4..].copy_from_slice(&payload[..8]);
            aead::Nonce::assume_unique_for_key(nonce)
        };

        let aad = aead::Aad::from(make_tls12_aad(
            seq,
            msg.typ,
            msg.version,
            payload.len() - GCM_OVERHEAD,
        ));

        let payload = msg.payload_mut();
        let plain_len = self
            .dec_key
            .open_within(nonce, aad, payload, GCM_EXPLICIT_NONCE_LEN..)
            .map_err(|_| Error::DecryptError)?
            .len();

        if plain_len > MAX_FRAGMENT_LEN {
            return Err(Error::PeerSentOversizedRecord);
        }

        payload.truncate(plain_len);
        Ok(msg.into_plain_message())
    }
}

impl MessageEncrypter for GcmMessageEncrypter {
    fn encrypt(&mut self, msg: BorrowedPlainMessage, seq: u64) -> Result<OpaqueMessage, Error> {
        let nonce = aead::Nonce::assume_unique_for_key(Nonce::new(&self.iv, seq).0);
        let aad = aead::Aad::from(make_tls12_aad(seq, msg.typ, msg.version, msg.payload.len()));

        let total_len = self.encrypted_payload_len(msg.payload.len());
        let mut payload = Vec::with_capacity(total_len);
        payload.extend_from_slice(&nonce.as_ref()[4..]);
        payload.extend_from_slice(msg.payload);

        self.enc_key
            .seal_in_place_separate_tag(nonce, aad, &mut payload[GCM_EXPLICIT_NONCE_LEN..])
            .map(|tag| payload.extend(tag.as_ref()))
            .map_err(|_| Error::EncryptError)?;

        Ok(OpaqueMessage::new(msg.typ, msg.version, payload))
    }

    fn encrypted_payload_len(&self, payload_len: usize) -> usize {
        payload_len + GCM_EXPLICIT_NONCE_LEN + self.enc_key.algorithm().tag_len()
    }
}

/// The RFC7905/RFC7539 ChaCha20Poly1305 construction.
/// This implementation does the AAD construction required in TLS1.2.
/// TLS1.3 uses `TLS13MessageEncrypter`.
struct ChaCha20Poly1305MessageEncrypter {
    enc_key: aead::LessSafeKey,
    enc_offset: Iv,
}

/// The RFC7905/RFC7539 ChaCha20Poly1305 construction.
/// This implementation does the AAD construction required in TLS1.2.
/// TLS1.3 uses `TLS13MessageDecrypter`.
struct ChaCha20Poly1305MessageDecrypter {
    dec_key: aead::LessSafeKey,
    dec_offset: Iv,
}

const CHACHAPOLY1305_OVERHEAD: usize = 16;

impl MessageDecrypter for ChaCha20Poly1305MessageDecrypter {
    fn decrypt(&mut self, mut msg: OpaqueMessage, seq: u64) -> Result<PlainMessage, Error> {
        let payload = msg.payload();

        if payload.len() < CHACHAPOLY1305_OVERHEAD {
            return Err(Error::DecryptError);
        }

        let nonce = aead::Nonce::assume_unique_for_key(Nonce::new(&self.dec_offset, seq).0);
        let aad = aead::Aad::from(make_tls12_aad(
            seq,
            msg.typ,
            msg.version,
            payload.len() - CHACHAPOLY1305_OVERHEAD,
        ));

        let payload = msg.payload_mut();
        let plain_len = self
            .dec_key
            .open_in_place(nonce, aad, payload)
            .map_err(|_| Error::DecryptError)?
            .len();

        if plain_len > MAX_FRAGMENT_LEN {
            return Err(Error::PeerSentOversizedRecord);
        }

        payload.truncate(plain_len);
        Ok(msg.into_plain_message())
    }
}

impl MessageEncrypter for ChaCha20Poly1305MessageEncrypter {
    fn encrypt(&mut self, msg: BorrowedPlainMessage, seq: u64) -> Result<OpaqueMessage, Error> {
        let nonce = aead::Nonce::assume_unique_for_key(Nonce::new(&self.enc_offset, seq).0);
        let aad = aead::Aad::from(make_tls12_aad(seq, msg.typ, msg.version, msg.payload.len()));

        let total_len = self.encrypted_payload_len(msg.payload.len());
        let mut buf = Vec::with_capacity(total_len);
        buf.extend_from_slice(msg.payload);

        self.enc_key
            .seal_in_place_append_tag(nonce, aad, &mut buf)
            .map_err(|_| Error::EncryptError)?;

        Ok(OpaqueMessage::new(msg.typ, msg.version, buf))
    }

    fn encrypted_payload_len(&self, payload_len: usize) -> usize {
        payload_len + self.enc_key.algorithm().tag_len()
    }
}

fn gcm_iv(write_iv: &[u8], explicit: &[u8]) -> Iv {
    debug_assert_eq!(write_iv.len(), 4);
    debug_assert_eq!(explicit.len(), 8);

    // The GCM nonce is constructed from a 32-bit 'salt' derived
    // from the master-secret, and a 64-bit explicit part,
    // with no specified construction.  Thanks for that.
    //
    // We use the same construction as TLS1.3/ChaCha20Poly1305:
    // a starting point extracted from the key block, xored with
    // the sequence number.
    let mut iv = [0; NONCE_LEN];
    iv[..4].copy_from_slice(write_iv);
    iv[4..].copy_from_slice(explicit);

    Iv::new(iv)
}