tor_netdoc/doc/hsdesc/build/
outer.rs

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1//! Functionality for encoding the outer document of an onion service descriptor.
2//!
3//! NOTE: `HsDescOuter` is a private helper for building hidden service descriptors, and is
4//! not meant to be used directly. Hidden services will use `HsDescBuilder` to build and encode
5//! hidden service descriptors.
6
7use crate::build::{NetdocBuilder, NetdocEncoder};
8use crate::doc::hsdesc::outer::{HsOuterKwd, HS_DESC_SIGNATURE_PREFIX, HS_DESC_VERSION_CURRENT};
9
10use rand::{CryptoRng, RngCore};
11use tor_bytes::EncodeError;
12use tor_cert::EncodedEd25519Cert;
13use tor_hscrypto::RevisionCounter;
14use tor_llcrypto::pk::ed25519;
15use tor_units::IntegerMinutes;
16
17use base64ct::{Base64Unpadded, Encoding};
18
19/// The representation of the outer wrapper of an onion service descriptor.
20///
21/// The format of this document is described in section 2.4. of rend-spec-v3.
22#[derive(Debug)]
23pub(super) struct HsDescOuter<'a> {
24    /// The short-term descriptor signing key.
25    pub(super) hs_desc_sign: &'a ed25519::Keypair,
26    /// The descriptor signing key certificate.
27    pub(super) hs_desc_sign_cert: EncodedEd25519Cert,
28    /// The lifetime of this descriptor, in minutes.
29    ///
30    /// This doesn't actually list the starting time or the end time for the
31    /// descriptor: presumably, because we didn't want to leak the onion
32    /// service's view of the wallclock.
33    pub(super) lifetime: IntegerMinutes<u16>,
34    /// A revision counter to tell whether this descriptor is more or less recent
35    /// than another one for the same blinded ID.
36    pub(super) revision_counter: RevisionCounter,
37    /// The (superencrypted) middle document of the onion service descriptor.
38    ///
39    /// The `superencrypted` field is created by encrypting an
40    /// [`build::middle::HsDescMiddle`](super::middle::HsDescMiddle)
41    /// middle document as described in
42    /// sections 2.5.1.1. and 2.5.1.2. of rend-spec-v3.
43    pub(super) superencrypted: Vec<u8>,
44}
45
46impl<'a> NetdocBuilder for HsDescOuter<'a> {
47    fn build_sign<R: RngCore + CryptoRng>(self, _: &mut R) -> Result<String, EncodeError> {
48        use HsOuterKwd::*;
49
50        let HsDescOuter {
51            hs_desc_sign,
52            hs_desc_sign_cert,
53            lifetime,
54            revision_counter,
55            superencrypted,
56        } = self;
57
58        let mut encoder = NetdocEncoder::new();
59        let beginning = encoder.cursor();
60        encoder.item(HS_DESCRIPTOR).arg(&HS_DESC_VERSION_CURRENT);
61        encoder.item(DESCRIPTOR_LIFETIME).arg(&lifetime.to_string());
62
63        encoder
64            .item(DESCRIPTOR_SIGNING_KEY_CERT)
65            .object("ED25519 CERT", hs_desc_sign_cert.as_ref());
66        encoder.item(REVISION_COUNTER).arg(&*revision_counter);
67        encoder
68            .item(SUPERENCRYPTED)
69            .object("MESSAGE", superencrypted);
70        let end = encoder.cursor();
71
72        let mut text = HS_DESC_SIGNATURE_PREFIX.to_vec();
73        text.extend_from_slice(encoder.slice(beginning, end)?.as_bytes());
74        let signature = hs_desc_sign.sign(&text);
75
76        // TODO SPEC encoding of this signature is completely unspecified (rend-spec-v3 2.4)
77        // TODO SPEC base64 is sometimes padded, sometimes unpadded, but NONE of the specs ever say!
78        encoder
79            .item(SIGNATURE)
80            .arg(&Base64Unpadded::encode_string(&signature.to_bytes()));
81
82        encoder.finish().map_err(|e| e.into())
83    }
84}
85
86#[cfg(test)]
87mod test {
88    // @@ begin test lint list maintained by maint/add_warning @@
89    #![allow(clippy::bool_assert_comparison)]
90    #![allow(clippy::clone_on_copy)]
91    #![allow(clippy::dbg_macro)]
92    #![allow(clippy::mixed_attributes_style)]
93    #![allow(clippy::print_stderr)]
94    #![allow(clippy::print_stdout)]
95    #![allow(clippy::single_char_pattern)]
96    #![allow(clippy::unwrap_used)]
97    #![allow(clippy::unchecked_duration_subtraction)]
98    #![allow(clippy::useless_vec)]
99    #![allow(clippy::needless_pass_by_value)]
100    //! <!-- @@ end test lint list maintained by maint/add_warning @@ -->
101
102    use std::time::UNIX_EPOCH;
103
104    use crate::doc::hsdesc::create_desc_sign_key_cert;
105
106    use super::*;
107    use tor_basic_utils::test_rng::Config;
108    use tor_hscrypto::pk::HsIdKeypair;
109    use tor_hscrypto::time::TimePeriod;
110    use tor_llcrypto::pk::ed25519::ExpandedKeypair;
111    use tor_units::IntegerMinutes;
112
113    // Some dummy bytes, not actually encrypted.
114    const TEST_SUPERENCRYPTED_VALUE: &[u8] = &[1, 2, 3, 4];
115
116    #[test]
117    fn outer_hsdesc() {
118        let mut rng = Config::Deterministic.into_rng();
119        let hs_id = ed25519::Keypair::generate(&mut rng);
120        let hs_desc_sign = ed25519::Keypair::generate(&mut rng);
121        let period = TimePeriod::new(
122            humantime::parse_duration("24 hours").unwrap(),
123            humantime::parse_rfc3339("2023-02-09T12:00:00Z").unwrap(),
124            humantime::parse_duration("12 hours").unwrap(),
125        )
126        .unwrap();
127        let (_public, blinded_id, _) = HsIdKeypair::from(ExpandedKeypair::from(&hs_id))
128            .compute_blinded_key(period)
129            .unwrap();
130
131        let hs_desc_sign_cert =
132            create_desc_sign_key_cert(&hs_desc_sign.verifying_key(), &blinded_id, UNIX_EPOCH)
133                .unwrap();
134
135        let hs_desc = HsDescOuter {
136            hs_desc_sign: &hs_desc_sign,
137            hs_desc_sign_cert,
138            lifetime: IntegerMinutes::new(20),
139            revision_counter: 9001.into(),
140            superencrypted: TEST_SUPERENCRYPTED_VALUE.into(),
141        }
142        .build_sign(&mut Config::Deterministic.into_rng())
143        .unwrap();
144
145        assert_eq!(
146            hs_desc,
147            r#"hs-descriptor 3
148descriptor-lifetime 20
149descriptor-signing-key-cert
150-----BEGIN ED25519 CERT-----
151AQgAAAAAAZZVJwNlzVw1ZQGO7MTzC5MsySASd+fswAcjdTJJOifXAQAgBACI78JJ
152/MuWPH0T5rQziVMJK/yETbYCVycypjsytCmeA4eiWhcVBG4r6AY/fXqHZnI3ApID
153fsb92Bs45IrOrkQdATb5mk1dlFb0X6+0wIF0P0gCVuAEkGv1kvcR/zpvhww=
154-----END ED25519 CERT-----
155revision-counter 9001
156superencrypted
157-----BEGIN MESSAGE-----
158AQIDBA==
159-----END MESSAGE-----
160signature g6wu776AYYD+BXPBocToRXPF9xob3TB34hkR1/h8tDBGjGMnBWZw03INbiX6Z8FaOXCulccQ309fYEO/BmwyDQ
161"#
162        );
163    }
164}
tor_netdoc/doc/hsdesc/build/outer.rs

tor_netdoc/doc/hsdesc/build/
outer.rs
