ytls-server 0.0.9

yolox sans-io TLS server context
Documentation 
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

//! yTLS Server Context: Client Finished

use crate::{CtxError, Rfc8446Error, ServerHandshakeCtx, TlsServerCtxConfig};
use ytls_traits::CryptoSha256HmacProcessor;
use ytls_traits::{CryptoConfig, CryptoRng};

use ytls_traits::Tls13KeyScheduleHandshakeSha256;

use ytls_record::ClientFinished;

impl<Config, Crypto, Rng> ServerHandshakeCtx<Config, Crypto, Rng>
where
    Config: TlsServerCtxConfig,
    Crypto: CryptoConfig,
    Rng: CryptoRng,
{
    pub(crate) fn check_client_finished<'r>(&self, f: &ClientFinished<'r>) -> Result<(), CtxError> {
        let expected_hmac_s = f.hmac();

        // TODO SHA384
        if expected_hmac_s.len() != 32 {
            return Err(CtxError::Rfc8446(Rfc8446Error::Unexpected));
        }

        let mut expected_hmac: [u8; 32] = [0; 32];
        expected_hmac.copy_from_slice(expected_hmac_s);

        let hash_finished = match self.hash_finished {
            Some(h) => h,
            None => {
                return Err(CtxError::Bug(
                    "Hash finished was not guarded for check_client_finished",
                ))
            }
        };

        let hs_key = match self.handshake_finished_client_key {
            Some(ref k) => k,
            None => &[
                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0,
            ],
        };

        let mut mac = Crypto::hmac_sha256_init_with_key(hs_key);
        mac.hmac_sha256_update(&hash_finished);

        let finished_hmac: [u8; 32] = mac.hmac_sha256_finalize();

        use ctutils::{Choice, CtEq};
        let cmp = finished_hmac.ct_ne(&expected_hmac);

        if cmp.to_u8() == 1 {
            return Err(CtxError::Rfc8446(Rfc8446Error::Decrypt));
        }

        Ok(())
    }
}