OXYGENHUB
◆ v0.4.4 oxygen / crates / oxy-core / src / identity.rs
25.3 KiB · Rust · last changed oxy receipt export --format slsa: SLSA provenance cosign can check 19 days ago source blame history raw
1983686f Andy McCall ↶ 1 
//! Identities and composite Ed25519 + ML-DSA-65 signatures (spec §14.2, §14.3).
2 
//!
3 
//! Both halves sign the same message, which binds the composite `KeyId`, and
4 
//! verification requires both. A signature with either half missing, wrong,
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//! or made for a different KeyId is invalid.
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7 
use crate::cbor::{self, Value};
8 
use crate::hash::{hash_object, KeyId, ObjectRef, ObjectType};
75167672 Andy McCall 9 
use crate::objects::{
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    array, bytes, check_version, field, oref, text, uint, ObjectError, FORMAT_VERSION,
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};
1983686f Andy McCall ↶ 12 
use ed25519_dalek::ed25519::signature::Signer as _;
75167672 Andy McCall 13 
use ed25519_dalek::{
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    Signature as EdSignature, SigningKey as EdSigningKey, VerifyingKey as EdVerifyingKey,
15 
};
16 
use ml_dsa::{
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    EncodedSignature, EncodedVerifyingKey, MlDsa65, Seed, Signature as MlSignature,
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    SigningKey as MlSigningKey, VerifyingKey as MlVerifyingKey,
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};
1983686f Andy McCall ↶ 20 
use rand::RngCore;
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22 
pub const ED25519_PK_LEN: usize = 32;
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pub const MLDSA65_PK_LEN: usize = 1952;
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pub const ED25519_SIG_LEN: usize = 64;
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pub const MLDSA65_SIG_LEN: usize = 3309;
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/// `alg` value for Ed25519 + ML-DSA-65.
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pub const ALG_COMPOSITE: u64 = 1;
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7ba155f2 Andy McCall ↶ 29 
/// What a delegate may do on the delegator's behalf (spec §14.2): a set of
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/// `changes` (sign individual changes), `seal` (seal batches of them) and
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/// `refs` (reference and tag attestations). An agent gets `changes` alone,
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/// so it can never move a reference, whatever its owner may do.
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#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
34 
pub struct Scope(u8);
35
36 
impl Scope {
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    pub const NONE: Scope = Scope(0);
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    pub const CHANGES: Scope = Scope(1);
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    pub const REFS: Scope = Scope(2);
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    pub const SEAL: Scope = Scope(4);
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    /// Everything: what a delegate could do before scopes existed.
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    pub const ALL: Scope = Scope(7);
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    const NAMES: [(Scope, &'static str); 3] = [
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        (Scope::CHANGES, "changes"),
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        (Scope::REFS, "refs"),
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        (Scope::SEAL, "seal"),
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    ];
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49 
    pub fn has(self, other: Scope) -> bool {
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        self.0 & other.0 == other.0
51 
    }
52 
    pub fn is_empty(self) -> bool {
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        self.0 == 0
54 
    }
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    /// The names in the set, in the order they are written.
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    pub fn names(self) -> Vec<&'static str> {
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        Self::NAMES
58 
            .iter()
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            .filter(|(s, _)| self.has(*s))
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            .map(|(_, n)| *n)
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            .collect()
62 
    }
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    fn named(name: &str) -> Option<Scope> {
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        Self::NAMES
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            .iter()
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            .find(|(_, n)| *n == name)
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            .map(|(s, _)| *s)
68 
    }
69 
    /// `changes,refs` (also with spaces); `all` is every scope.
70 
    pub fn parse(s: &str) -> Result<Scope, String> {
71 
        let mut out = Scope::NONE;
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        for part in s.split(',').map(str::trim).filter(|p| !p.is_empty()) {
73 
            if part == "all" {
74 
                return Ok(Scope::ALL);
75 
            }
76 
            match Self::named(part) {
77 
                Some(sc) => out = out | sc,
78 
                None => return Err(format!("unknown scope {part:?}: use changes, refs or seal")),
79 
            }
80 
        }
81 
        if out.is_empty() {
82 
            return Err("a delegate needs at least one scope: changes, refs or seal".into());
83 
        }
84 
        Ok(out)
85 
    }
86 
}
87
88 
impl std::ops::BitOr for Scope {
89 
    type Output = Scope;
90 
    fn bitor(self, rhs: Scope) -> Scope {
91 
        Scope(self.0 | rhs.0)
92 
    }
93 
}
94
95 
impl std::fmt::Display for Scope {
96 
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
97 
        f.write_str(&self.names().join(","))
98 
    }
99 
}
100
101 
impl std::fmt::Debug for Scope {
102 
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
103 
        write!(f, "Scope({self})")
104 
    }
105 
}
106
107 
/// A key allowed to act for an identity, within `scope`, until `expires`
108 
/// (wall milliseconds; `None` for as long as the delegation stands).
109 
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
110 
pub struct Delegate {
111 
    pub key: KeyId,
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    pub scope: Scope,
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    pub expires: Option<u64>,
114 
}
115
116 
impl Delegate {
117 
    /// A delegate with every scope and no expiry of its own.
118 
    pub fn full(key: KeyId) -> Delegate {
119 
        Delegate {
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            key,
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            scope: Scope::ALL,
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            expires: None,
123 
        }
124 
    }
125 
    /// Whether the delegation covers `scope` at `at_ms`.
126 
    pub fn allows(&self, scope: Scope, at_ms: u64) -> bool {
127 
        self.scope.has(scope) && !self.expires.is_some_and(|e| at_ms > e)
128 
    }
129 
    fn to_value(self) -> Value {
130 
        Value::map([
131 
            (0, Value::Bytes(self.key.0.to_vec())),
132 
            (
133 
                1,
134 
                Value::Array(
135 
                    self.scope
136 
                        .names()
137 
                        .into_iter()
138 
                        .map(|n| Value::Text(n.to_string()))
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                        .collect(),
140 
                ),
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            ),
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            (2, self.expires.map(Value::Uint).unwrap_or(Value::Null)),
143 
        ])
144 
    }
145 
    /// An entry, or a bare KeyId as identities carried before scopes
146 
    /// existed, which meant every scope.
147 
    fn from_value(v: &Value) -> Result<Delegate, ObjectError> {
148 
        if let Value::Bytes(_) = v {
149 
            return Ok(Delegate::full(oref(v, "delegate")?));
150 
        }
151 
        let m = v
152 
            .as_map()
153 
            .ok_or_else(|| ObjectError::Schema("delegate: expected map".into()))?;
154 
        let key = oref(field(m, 0, "delegate key")?, "delegate key")?;
155 
        let mut scope = Scope::NONE;
156 
        for n in array(field(m, 1, "delegate scope")?, "delegate scope")? {
157 
            let n = text(n, "delegate scope")?;
158 
            scope = scope
159 
                | Scope::named(n)
160 
                    .ok_or_else(|| ObjectError::Schema(format!("delegate: unknown scope {n:?}")))?;
161 
        }
162 
        let expires = match field(m, 2, "delegate expires")? {
163 
            v if v.is_null() => None,
164 
            v => Some(uint(v, "delegate expires")?),
165 
        };
166 
        Ok(Delegate {
167 
            key,
168 
            scope,
169 
            expires,
170 
        })
171 
    }
172 
}
173
1983686f Andy McCall ↶ 174 
#[derive(Clone, Debug, PartialEq, Eq)]
175 
pub struct Identity {
176 
    pub ed25519_pk: [u8; ED25519_PK_LEN],
177 
    pub mldsa65_pk: Vec<u8>,
178 
    pub name: String,
179 
    pub email: String,
180 
    pub created: u64,
181 
    pub expires: Option<u64>,
182 
    pub previous: Option<KeyId>,
7ba155f2 Andy McCall ↶ 183 
    pub delegates: Vec<Delegate>,
184 
}
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186 
/// Sorted by key, one entry per key.
187 
fn tidy(mut delegates: Vec<Delegate>) -> Vec<Delegate> {
188 
    delegates.sort_by_key(|d| d.key);
189 
    delegates.dedup_by(|a, b| a.key == b.key);
190 
    delegates
1983686f Andy McCall ↶ 191 
}
192
193 
impl Identity {
7ba155f2 Andy McCall ↶ 194 
    /// The delegation to `key`, if any.
195 
    pub fn delegate(&self, key: &KeyId) -> Option<&Delegate> {
196 
        self.delegates.iter().find(|d| d.key == *key)
197 
    }
198 
    /// Whether `key` may act for this identity within `scope` at `at_ms`.
199 
    pub fn delegates_to(&self, key: &KeyId, scope: Scope, at_ms: u64) -> bool {
200 
        self.delegate(key).is_some_and(|d| d.allows(scope, at_ms))
201 
    }
1983686f Andy McCall ↶ 202 
    pub fn to_value(&self) -> Value {
203 
        Value::map([
204 
            (0, Value::Uint(FORMAT_VERSION)),
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            (1, Value::Bytes(self.ed25519_pk.to_vec())),
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            (2, Value::Bytes(self.mldsa65_pk.clone())),
207 
            (3, Value::Text(self.name.clone())),
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            (4, Value::Text(self.email.clone())),
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            (5, Value::Uint(self.created)),
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            (6, self.expires.map(Value::Uint).unwrap_or(Value::Null)),
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            (
212 
                7,
213 
                self.previous
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                    .map(|p| Value::Bytes(p.0.to_vec()))
215 
                    .unwrap_or(Value::Null),
216 
            ),
217 
            (
218 
                8,
7ba155f2 Andy McCall ↶ 219 
                Value::Array(self.delegates.iter().map(|d| d.to_value()).collect()),
75167672 Andy McCall 220 
            ),
1983686f Andy McCall ↶ 221 
        ])
222 
    }
223 
    pub fn encode(&self) -> Vec<u8> {
224 
        cbor::encode(&self.to_value())
225 
    }
226 
    pub fn hash(&self) -> KeyId {
227 
        hash_object(ObjectType::Identity, &self.encode())
228 
    }
229 
    pub fn decode(b: &[u8]) -> Result<Identity, ObjectError> {
230 
        let v = cbor::decode(b)?;
75167672 Andy McCall 231 
        let m = v
232 
            .as_map()
233 
            .ok_or_else(|| ObjectError::Schema("identity: expected map".into()))?;
1983686f Andy McCall ↶ 234 
        check_version(m)?;
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        let ed = bytes(field(m, 1, "ed25519_pk")?, "ed25519_pk")?;
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        let ml = bytes(field(m, 2, "mldsa65_pk")?, "mldsa65_pk")?;
237 
        if ed.len() != ED25519_PK_LEN || ml.len() != MLDSA65_PK_LEN {
75167672 Andy McCall 238 
            return Err(ObjectError::Schema(
239 
                "identity: wrong public key length".into(),
240 
            ));
1983686f Andy McCall ↶ 241 
        }
75167672 Andy McCall 242 
        let opt_u = |v: &Value| -> Result<Option<u64>, ObjectError> {
243 
            if v.is_null() {
244 
                Ok(None)
245 
            } else {
246 
                uint(v, "expires").map(Some)
247 
            }
248 
        };
249 
        let opt_r = |v: &Value| -> Result<Option<KeyId>, ObjectError> {
250 
            if v.is_null() {
251 
                Ok(None)
252 
            } else {
253 
                oref(v, "previous").map(Some)
254 
            }
255 
        };
7ba155f2 Andy McCall ↶ 256 
        let delegates = tidy(
257 
            array(field(m, 8, "delegates")?, "delegates")?
258 
                .iter()
259 
                .map(Delegate::from_value)
260 
                .collect::<Result<Vec<_>, _>>()?,
261 
        );
1983686f Andy McCall ↶ 262 
        Ok(Identity {
263 
            ed25519_pk: ed.try_into().unwrap(),
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            mldsa65_pk: ml.to_vec(),
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            name: text(field(m, 3, "name")?, "name")?.to_owned(),
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            email: text(field(m, 4, "email")?, "email")?.to_owned(),
267 
            created: uint(field(m, 5, "created")?, "created")?,
268 
            expires: opt_u(field(m, 6, "expires")?)?,
269 
            previous: opt_r(field(m, 7, "previous")?)?,
270 
            delegates,
271 
        })
272 
    }
273
28fc23d7 Andy McCall ↶ 274 
    /// Whether the identity is past its expiry at `now_ms`.
275 
    pub fn is_expired_at(&self, now_ms: u64) -> bool {
276 
        self.expires.is_some_and(|e| now_ms > e)
277 
    }
278
279 
    /// A successor identity with the same keys, `previous` set to this
280 
    /// identity's KeyId, and the given delegates and expiry (spec §14.2).
7ba155f2 Andy McCall ↶ 281 
    pub fn successor(
282 
        &self,
283 
        delegates: Vec<Delegate>,
284 
        expires: Option<u64>,
285 
        created: u64,
286 
    ) -> Identity {
75167672 Andy McCall 287 
        Identity {
288 
            previous: Some(self.hash()),
7ba155f2 Andy McCall ↶ 289 
            delegates: tidy(delegates),
75167672 Andy McCall 290 
            expires,
291 
            created,
292 
            ..self.clone()
293 
        }
28fc23d7 Andy McCall ↶ 294 
    }
295
a39754d0 Andy McCall ↶ 296 
    /// Check a [`SecretKey::sign_ed25519`] signature by this identity.
297 
    pub fn verify_ed25519(&self, msg: &[u8], sig: &[u8]) -> Result<(), VerifyError> {
298 
        let sig = EdSignature::from_slice(sig).map_err(|_| VerifyError::Ed25519)?;
299 
        self.ed_key()?
300 
            .verify_strict(msg, &sig)
301 
            .map_err(|_| VerifyError::Ed25519)
302 
    }
303
1983686f Andy McCall ↶ 304 
    fn ed_key(&self) -> Result<EdVerifyingKey, VerifyError> {
305 
        EdVerifyingKey::from_bytes(&self.ed25519_pk).map_err(|_| VerifyError::BadKey)
306 
    }
307 
    fn ml_key(&self) -> Result<MlVerifyingKey<MlDsa65>, VerifyError> {
75167672 Andy McCall 308 
        let enc = EncodedVerifyingKey::<MlDsa65>::try_from(self.mldsa65_pk.as_slice())
309 
            .map_err(|_| VerifyError::BadKey)?;
1983686f Andy McCall ↶ 310 
        Ok(MlVerifyingKey::decode(&enc))
311 
    }
312 
}
313
314 
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
315 
pub enum Domain {
316 
    Change,
317 
    Attest,
83e0677b Andy McCall ↶ 318 
    Policy,
7aa2dc93 Andy McCall ↶ 319 
    /// A server-issued challenge, proving possession of a key to a host
320 
    /// (hub spec §5.3, §5.4). Never a stored object.
321 
    Challenge,
1983686f Andy McCall ↶ 322 
}
323
324 
impl Domain {
325 
    pub fn name(self) -> &'static str {
326 
        match self {
327 
            Domain::Change => "change",
328 
            Domain::Attest => "attest",
83e0677b Andy McCall ↶ 329 
            Domain::Policy => "policy",
7aa2dc93 Andy McCall ↶ 330 
            Domain::Challenge => "challenge",
1983686f Andy McCall ↶ 331 
        }
332 
    }
333 
}
334
335 
/// `"oxy1 sig " || domain || 0x00 || KeyId || target` (spec §14.3).
336 
pub fn signing_message(domain: Domain, key: &KeyId, target: &ObjectRef) -> Vec<u8> {
337 
    let mut m = Vec::with_capacity(80);
338 
    m.extend_from_slice(b"oxy1 sig ");
339 
    m.extend_from_slice(domain.name().as_bytes());
340 
    m.push(0);
341 
    m.extend_from_slice(&key.0);
342 
    m.extend_from_slice(&target.0);
343 
    m
344 
}
345
346 
#[derive(Clone, PartialEq, Eq)]
347 
pub struct Signature {
348 
    pub key: KeyId,
349 
    pub ed: [u8; ED25519_SIG_LEN],
350 
    pub ml: Vec<u8>,
351 
}
352
353 
impl std::fmt::Debug for Signature {
354 
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
355 
        write!(f, "Signature(key {:?})", self.key)
356 
    }
357 
}
358
359 
impl Signature {
360 
    pub fn to_value(&self) -> Value {
361 
        Value::map([
362 
            (0, Value::Bytes(self.key.0.to_vec())),
363 
            (1, Value::Uint(ALG_COMPOSITE)),
364 
            (2, Value::Bytes(self.ed.to_vec())),
365 
            (3, Value::Bytes(self.ml.clone())),
366 
        ])
367 
    }
368 
    pub fn from_value(v: &Value) -> Result<Signature, ObjectError> {
75167672 Andy McCall 369 
        let m = v
370 
            .as_map()
371 
            .ok_or_else(|| ObjectError::Schema("signature: expected map".into()))?;
1983686f Andy McCall ↶ 372 
        let alg = uint(field(m, 1, "alg")?, "alg")?;
373 
        if alg != ALG_COMPOSITE {
75167672 Andy McCall 374 
            return Err(ObjectError::Schema(format!(
375 
                "unknown signature algorithm {alg}"
376 
            )));
1983686f Andy McCall ↶ 377 
        }
378 
        let ed = bytes(field(m, 2, "ed")?, "ed")?;
379 
        let ml = bytes(field(m, 3, "ml")?, "ml")?;
380 
        if ed.len() != ED25519_SIG_LEN || ml.len() != MLDSA65_SIG_LEN {
381 
            return Err(ObjectError::Schema("signature: wrong length".into()));
382 
        }
75167672 Andy McCall 383 
        Ok(Signature {
384 
            key: oref(field(m, 0, "key")?, "key")?,
385 
            ed: ed.try_into().unwrap(),
386 
            ml: ml.to_vec(),
387 
        })
1983686f Andy McCall ↶ 388 
    }
389 
    pub fn encode_list(sigs: &[Signature]) -> Vec<u8> {
390 
        cbor::encode(&Value::Array(sigs.iter().map(|s| s.to_value()).collect()))
391 
    }
392 
    pub fn decode_list(b: &[u8]) -> Result<Vec<Signature>, ObjectError> {
393 
        let v = cbor::decode(b)?;
75167672 Andy McCall 394 
        array(&v, "signatures")?
395 
            .iter()
396 
            .map(Signature::from_value)
397 
            .collect()
1983686f Andy McCall ↶ 398 
    }
399 
}
400
401 
#[derive(Clone, Copy, Debug, PartialEq, Eq, thiserror::Error)]
402 
pub enum VerifyError {
403 
    #[error("signature names a different key than the identity")]
404 
    KeyMismatch,
405 
    #[error("identity holds a malformed public key")]
406 
    BadKey,
407 
    #[error("Ed25519 signature invalid")]
408 
    Ed25519,
409 
    #[error("ML-DSA-65 signature invalid")]
410 
    MlDsa,
7aa2dc93 Andy McCall ↶ 411 
    #[error("a challenge is at least 16 bytes")]
412 
    ShortChallenge,
1983686f Andy McCall ↶ 413 
}
414
415 
/// Verify a composite signature by `identity` over `target` (spec §14.3).
75167672 Andy McCall 416 
pub fn verify(
417 
    identity: &Identity,
418 
    sig: &Signature,
419 
    domain: Domain,
420 
    target: &ObjectRef,
421 
) -> Result<(), VerifyError> {
1983686f Andy McCall ↶ 422 
    let key = identity.hash();
423 
    if sig.key != key {
424 
        return Err(VerifyError::KeyMismatch);
425 
    }
426 
    let msg = signing_message(domain, &key, target);
427 
    let ed_sig = EdSignature::from_bytes(&sig.ed);
75167672 Andy McCall 428 
    identity
429 
        .ed_key()?
430 
        .verify_strict(&msg, &ed_sig)
431 
        .map_err(|_| VerifyError::Ed25519)?;
432 
    let enc =
433 
        EncodedSignature::<MlDsa65>::try_from(sig.ml.as_slice()).map_err(|_| VerifyError::MlDsa)?;
1983686f Andy McCall ↶ 434 
    let ml_sig = MlSignature::<MlDsa65>::decode(&enc).ok_or(VerifyError::MlDsa)?;
435 
    if !identity.ml_key()?.verify_with_context(&msg, b"", &ml_sig) {
436 
        return Err(VerifyError::MlDsa);
437 
    }
438 
    Ok(())
439 
}
440
441 
/// The seeds of a composite key pair. Stored only in the user's key directory.
442 
#[derive(Clone)]
443 
pub struct SecretKey {
444 
    pub ed_seed: [u8; 32],
445 
    pub ml_seed: [u8; 32],
446 
}
447
448 
impl std::fmt::Debug for SecretKey {
449 
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
450 
        f.write_str("SecretKey(..)")
451 
    }
452 
}
453
454 
impl SecretKey {
455 
    pub fn generate() -> SecretKey {
456 
        let mut ed_seed = [0u8; 32];
457 
        let mut ml_seed = [0u8; 32];
458 
        rand::rngs::OsRng.fill_bytes(&mut ed_seed);
459 
        rand::rngs::OsRng.fill_bytes(&mut ml_seed);
460 
        SecretKey { ed_seed, ml_seed }
461 
    }
462
463 
    fn ed(&self) -> EdSigningKey {
464 
        EdSigningKey::from_bytes(&self.ed_seed)
465 
    }
466 
    fn ml(&self) -> MlSigningKey<MlDsa65> {
467 
        MlSigningKey::from_seed(&Seed::from(self.ml_seed))
468 
    }
469
470 
    /// The identity object for these keys.
471 
    pub fn identity(&self, name: &str, email: &str, created: u64) -> Identity {
472 
        Identity {
473 
            ed25519_pk: self.ed().verifying_key().to_bytes(),
75167672 Andy McCall 474 
            mldsa65_pk: self
475 
                .ml()
476 
                .expanded_key()
477 
                .verifying_key()
478 
                .encode()
479 
                .as_slice()
480 
                .to_vec(),
1983686f Andy McCall ↶ 481 
            name: name.into(),
482 
            email: email.into(),
483 
            created,
484 
            expires: None,
485 
            previous: None,
486 
            delegates: vec![],
487 
        }
a39754d0 Andy McCall ↶ 488 
    }
489
490 
    /// Ed25519 alone over `msg`, for a format that separates its own
491 
    /// domain and whose verifiers know only Ed25519 (DSSE: see
492 
    /// [`crate::dsse`]). Oxygen's own objects are signed with [`Self::sign`].
493 
    pub fn sign_ed25519(&self, msg: &[u8]) -> [u8; 64] {
494 
        self.ed().sign(msg).to_bytes()
1983686f Andy McCall ↶ 495 
    }
496
497 
    pub fn sign(&self, domain: Domain, key: &KeyId, target: &ObjectRef) -> Signature {
498 
        let msg = signing_message(domain, key, target);
499 
        let ed = self.ed().sign(&msg).to_bytes();
75167672 Andy McCall 500 
        let ml = self
501 
            .ml()
502 
            .expanded_key()
503 
            .sign_deterministic(&msg, b"")
504 
            .expect("empty context is valid")
505 
            .encode()
506 
            .as_slice()
507 
            .to_vec();
1983686f Andy McCall ↶ 508 
        Signature { key: *key, ed, ml }
509 
    }
510
511 
    pub fn encode(&self, key: &KeyId) -> Vec<u8> {
512 
        cbor::encode(&Value::map([
513 
            (0, Value::Uint(FORMAT_VERSION)),
514 
            (1, Value::Bytes(key.0.to_vec())),
515 
            (2, Value::Bytes(self.ed_seed.to_vec())),
516 
            (3, Value::Bytes(self.ml_seed.to_vec())),
517 
        ]))
518 
    }
519
520 
    pub fn decode(b: &[u8]) -> Result<(KeyId, SecretKey), ObjectError> {
521 
        let v = cbor::decode(b)?;
75167672 Andy McCall 522 
        let m = v
523 
            .as_map()
524 
            .ok_or_else(|| ObjectError::Schema("secret key: expected map".into()))?;
1983686f Andy McCall ↶ 525 
        check_version(m)?;
526 
        let seed = |k: u64| -> Result<[u8; 32], ObjectError> {
75167672 Andy McCall 527 
            bytes(field(m, k, "seed")?, "seed")?
528 
                .try_into()
529 
                .map_err(|_| ObjectError::Schema("seed: expected 32 bytes".into()))
1983686f Andy McCall ↶ 530 
        };
75167672 Andy McCall 531 
        Ok((
532 
            oref(field(m, 1, "key")?, "key")?,
533 
            SecretKey {
534 
                ed_seed: seed(2)?,
535 
                ml_seed: seed(3)?,
536 
            },
537 
        ))
1983686f Andy McCall ↶ 538 
    }
539 
}
540
541 
#[cfg(test)]
542 
mod tests {
543 
    use super::*;
544
545 
    fn fixed_key() -> SecretKey {
75167672 Andy McCall 546 
        SecretKey {
547 
            ed_seed: [1; 32],
548 
            ml_seed: [2; 32],
549 
        }
1983686f Andy McCall ↶ 550 
    }
551
552 
    #[test]
553 
    fn identity_round_trip_and_sizes() {
554 
        let sk = fixed_key();
555 
        let id = sk.identity("Ada", "[email protected]", 1_700_000_000_000);
556 
        assert_eq!(id.mldsa65_pk.len(), MLDSA65_PK_LEN);
557 
        let d = Identity::decode(&id.encode()).unwrap();
558 
        assert_eq!(d, id);
559 
        assert_eq!(d.hash(), id.hash());
560 
        // Deterministic from seeds.
75167672 Andy McCall 561 
        assert_eq!(
562 
            fixed_key()
563 
                .identity("Ada", "[email protected]", 1_700_000_000_000)
564 
                .hash(),
565 
            id.hash()
566 
        );
1983686f Andy McCall ↶ 567 
        let mut other = id.clone();
7ba155f2 Andy McCall ↶ 568 
        other.delegates.push(Delegate::full(ObjectRef([9; 32])));
1983686f Andy McCall ↶ 569 
        assert_ne!(other.hash(), id.hash());
7ba155f2 Andy McCall ↶ 570 
    }
571
572 
    #[test]
573 
    fn delegates_carry_scope_and_expiry_and_bare_keys_mean_every_scope() {
574 
        let sk = fixed_key();
575 
        let mut id = sk.identity("Ada", "[email protected]", 1_700_000_000_000);
576 
        let agent = ObjectRef([7; 32]);
577 
        let host = ObjectRef([3; 32]);
578 
        id.delegates = vec![
579 
            Delegate {
580 
                key: agent,
581 
                scope: Scope::CHANGES,
582 
                expires: Some(2_000),
583 
            },
584 
            Delegate {
585 
                key: host,
586 
                scope: Scope::CHANGES | Scope::REFS,
587 
                expires: None,
588 
            },
589 
        ];
590 
        let d = Identity::decode(&id.encode()).unwrap();
591 
        assert_eq!(d.delegates.len(), 2);
592 
        assert!(d.delegates_to(&agent, Scope::CHANGES, 1_000));
593 
        assert!(!d.delegates_to(&agent, Scope::CHANGES, 2_001), "expired");
594 
        assert!(!d.delegates_to(&agent, Scope::REFS, 1_000));
595 
        assert!(!d.delegates_to(&agent, Scope::SEAL, 1_000));
596 
        assert!(d.delegates_to(&host, Scope::REFS, u64::MAX));
597 
        assert!(!d.delegates_to(&host, Scope::SEAL, 0));
598 
        assert!(!d.delegates_to(&ObjectRef([1; 32]), Scope::CHANGES, 0));
599 
        assert_eq!(
600 
            Scope::parse("changes, refs").unwrap(),
601 
            Scope::CHANGES | Scope::REFS
602 
        );
603 
        assert_eq!(Scope::parse("all").unwrap(), Scope::ALL);
604 
        assert_eq!((Scope::CHANGES | Scope::SEAL).to_string(), "changes,seal");
605 
        assert!(Scope::parse("push").is_err() && Scope::parse("").is_err());
606 
        // An identity written before scopes existed lists bare KeyIds.
607 
        let mut v = id.to_value();
608 
        if let Value::Map(m) = &mut v {
609 
            m.insert(8, Value::Array(vec![Value::Bytes(host.0.to_vec())]));
610 
        }
611 
        let old = Identity::decode(&cbor::encode(&v)).unwrap();
612 
        assert_eq!(old.delegates, vec![Delegate::full(host)]);
613 
        assert!(old.delegates_to(&host, Scope::ALL, u64::MAX));
1983686f Andy McCall ↶ 614 
    }
615
616 
    #[test]
617 
    fn sign_and_verify() {
618 
        let sk = fixed_key();
619 
        let id = sk.identity("Ada", "[email protected]", 1);
620 
        let key = id.hash();
621 
        let target = ObjectRef([7; 32]);
622 
        let sig = sk.sign(Domain::Change, &key, &target);
623 
        assert_eq!(sig.ml.len(), MLDSA65_SIG_LEN);
624 
        assert_eq!(verify(&id, &sig, Domain::Change, &target), Ok(()));
625 
        // Different target, different domain: invalid.
75167672 Andy McCall 626 
        assert_eq!(
627 
            verify(&id, &sig, Domain::Change, &ObjectRef([8; 32])),
628 
            Err(VerifyError::Ed25519)
629 
        );
630 
        assert_eq!(
631 
            verify(&id, &sig, Domain::Attest, &target),
632 
            Err(VerifyError::Ed25519)
633 
        );
1983686f Andy McCall ↶ 634 
        // Deterministic signatures.
635 
        assert_eq!(sk.sign(Domain::Change, &key, &target), sig);
636 
        // Signature list round trip.
75167672 Andy McCall 637 
        let l =
638 
            Signature::decode_list(&Signature::encode_list(std::slice::from_ref(&sig))).unwrap();
1983686f Andy McCall ↶ 639 
        assert_eq!(l, vec![sig]);
640 
    }
641
642 
    #[test]
643 
    fn stripping_or_forging_either_half_fails() {
644 
        let sk = fixed_key();
645 
        let id = sk.identity("Ada", "a@b", 1);
646 
        let key = id.hash();
647 
        let target = ObjectRef([7; 32]);
648 
        let good = sk.sign(Domain::Change, &key, &target);
649
650 
        let mut no_ml = good.clone();
651 
        no_ml.ml = vec![0; MLDSA65_SIG_LEN];
75167672 Andy McCall 652 
        assert_eq!(
653 
            verify(&id, &no_ml, Domain::Change, &target),
654 
            Err(VerifyError::MlDsa)
655 
        );
1983686f Andy McCall ↶ 656
657 
        let mut bad_ed = good.clone();
658 
        bad_ed.ed[10] ^= 1;
75167672 Andy McCall 659 
        assert_eq!(
660 
            verify(&id, &bad_ed, Domain::Change, &target),
661 
            Err(VerifyError::Ed25519)
662 
        );
1983686f Andy McCall ↶ 663
664 
        // A signature made for another KeyId over the same target does not transfer.
75167672 Andy McCall 665 
        let other = SecretKey {
666 
            ed_seed: [3; 32],
667 
            ml_seed: [4; 32],
668 
        };
1983686f Andy McCall ↶ 669 
        let other_id = other.identity("Bob", "b@b", 1);
670 
        let theirs = other.sign(Domain::Change, &other_id.hash(), &target);
75167672 Andy McCall 671 
        assert_eq!(
672 
            verify(&id, &theirs, Domain::Change, &target),
673 
            Err(VerifyError::KeyMismatch)
674 
        );
1983686f Andy McCall ↶ 675 
        let mut relabelled = theirs.clone();
676 
        relabelled.key = key;
75167672 Andy McCall 677 
        assert_eq!(
678 
            verify(&id, &relabelled, Domain::Change, &target),
679 
            Err(VerifyError::Ed25519)
680 
        );
1983686f Andy McCall ↶ 681
682 
        // Wrong length is rejected at decode time.
683 
        let mut short = good.to_value();
684 
        if let Value::Map(m) = &mut short {
685 
            m.insert(3, Value::Bytes(vec![0; 10]));
686 
        }
687 
        assert!(Signature::from_value(&short).is_err());
688 
    }
689
690 
    #[test]
691 
    fn secret_key_round_trip() {
692 
        let sk = fixed_key();
693 
        let key = sk.identity("x", "y", 0).hash();
694 
        let (k, d) = SecretKey::decode(&sk.encode(&key)).unwrap();
695 
        assert_eq!(k, key);
696 
        assert_eq!(d.ed_seed, sk.ed_seed);
697 
        assert_eq!(d.ml_seed, sk.ml_seed);
698 
        assert_ne!(SecretKey::generate().ed_seed, SecretKey::generate().ed_seed);
699 
    }
700 
}
7aa2dc93 Andy McCall ↶ 701
702 
/// The signing target of a challenge: `BLAKE3-256("oxy1 challenge " || bytes)`,
703 
/// so a challenge can never collide with a stored object's reference.
704 
pub fn challenge_target(challenge: &[u8]) -> ObjectRef {
705 
    let mut h = blake3::Hasher::new();
706 
    h.update(b"oxy1 challenge ");
707 
    h.update(challenge);
708 
    ObjectRef(*h.finalize().as_bytes())
709 
}
710
711 
impl SecretKey {
712 
    /// Sign a host's challenge (at least 16 bytes) with this key.
713 
    pub fn sign_challenge(&self, key: &KeyId, challenge: &[u8]) -> Result<Signature, VerifyError> {
714 
        if challenge.len() < 16 {
715 
            return Err(VerifyError::ShortChallenge);
716 
        }
717 
        Ok(self.sign(Domain::Challenge, key, &challenge_target(challenge)))
718 
    }
719 
}
720
721 
/// Check a challenge signature against the identity that claims it.
119bbf50 Andy McCall ↶ 722 
pub fn verify_challenge(
723 
    identity: &Identity,
724 
    sig: &Signature,
725 
    challenge: &[u8],
726 
) -> Result<(), VerifyError> {
7aa2dc93 Andy McCall ↶ 727 
    if challenge.len() < 16 {
728 
        return Err(VerifyError::ShortChallenge);
729 
    }
730 
    if sig.key != identity.hash() {
731 
        return Err(VerifyError::KeyMismatch);
732 
    }
119bbf50 Andy McCall ↶ 733 
    verify(
734 
        identity,
735 
        sig,
736 
        Domain::Challenge,
737 
        &challenge_target(challenge),
738 
    )
7aa2dc93 Andy McCall ↶ 739 
}
740
741 
#[cfg(test)]
742 
mod challenge_tests {
743 
    use super::*;
744
745 
    #[test]
746 
    fn a_challenge_signature_binds_key_and_bytes() {
747 
        let sk = SecretKey::generate();
748 
        let id = sk.identity("A", "a@example", 1);
749 
        let key = id.hash();
750 
        let challenge = [7u8; 32];
751 
        let sig = sk.sign_challenge(&key, &challenge).unwrap();
752 
        assert!(verify_challenge(&id, &sig, &challenge).is_ok());
119bbf50 Andy McCall ↶ 753 
        assert!(
754 
            verify_challenge(&id, &sig, &[8u8; 32]).is_err(),
755 
            "other bytes"
756 
        );
7aa2dc93 Andy McCall ↶ 757 
        let other = SecretKey::generate().identity("B", "b@example", 1);
119bbf50 Andy McCall ↶ 758 
        assert!(
759 
            verify_challenge(&other, &sig, &challenge).is_err(),
760 
            "other identity"
761 
        );
7aa2dc93 Andy McCall ↶ 762 
        assert!(sk.sign_challenge(&key, b"short").is_err());
763 
        // A challenge target never equals a change signature's target for the same bytes.
764 
        assert_ne!(challenge_target(&challenge), ObjectRef(challenge));
765 
    }
766 
}