cert.rs 93.8%

305 of 325 lines run, 33 of 70 functions · run #348 on paths-for-resolutions-and-amend · run missed

//! Certificates for short-lived keys (spec §14.7, oxygenhub#241,
//! oxygenhub docs/keyless.md). An issuer, a hub's key, binds a fresh key
//! to the identity that proved itself (an OIDC subject) for minutes: a Flow
//! job or an agent signs with that key and throws it away. The certificate
//! is signed with the issuer's composite key, so it is post-quantum like
//! every other signature in Oxygen.
//!
//! Whether to trust an issuer, and for which subjects, is the trust
//! policy's (§14.5); whether a signature was made inside the certificate's
//! window needs time the signer does not choose, which the caller passes
//! in (a host's acceptance now, the transparency log's later).

use crate::cbor::{self, Value};
use crate::hash::{hash_object, KeyId, ObjectRef, ObjectType};
use crate::identity::{verify, Domain, Identity, Scope, SecretKey, Signature};
use crate::objects::{array, bytes, check_version, field, map, oref, text, uint, ObjectError};

/// The longest a certificate may be valid. Jobs get ten minutes; an hour
/// leaves room for an issuer that rounds up, and no more.
pub const MAX_LIFETIME_MS: u64 = 60 * 60 * 1000;

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Certificate {
    /// The short-lived key's public identity.
    pub key: Identity,
    /// The issuer's KeyId (a hub's key).
    pub issuer: KeyId,
    /// Who proved it: `repo:OWNER/NAME:bookmark:B`, `agent:NAME@ACCOUNT`.
    pub subject: String,
    /// What else the proof said (environment, run, job), sorted by name.
    pub claims: Vec<(String, String)>,
    /// What the key may sign: changes, refs, seals.
    pub scope: Scope,
    /// Valid from and until, in wall milliseconds.
    pub not_before: u64,
    pub expires: u64,
    /// The grant that lets the subject act for an author, when an agent
    /// asked with one (field 8, only when present).
    pub grant: Option<SignedGrant>,
}

impl Certificate {
    pub fn to_value(&self) -> Value {
        let mut claims = self.claims.clone();
        claims.sort();
        let mut v = Value::map([
            (0, Value::Uint(1)),
            (1, Value::Bytes(self.key.encode())),
            (2, Value::Bytes(self.issuer.0.to_vec())),
            (3, Value::Text(self.subject.clone())),
            (
                4,
                Value::Array(
                    claims
                        .into_iter()
                        .map(|(k, v)| Value::Array(vec![Value::Text(k), Value::Text(v)]))
                        .collect(),
                ),
            ),
            (
                5,
                Value::Array(
                    self.scope
                        .names()
                        .into_iter()
                        .map(|n| Value::Text(n.to_string()))
                        .collect(),
                ),
            ),
            (6, Value::Uint(self.not_before)),
            (7, Value::Uint(self.expires)),
        ]);
        if let (Some(g), Value::Map(m)) = (&self.grant, &mut v) {
            m.insert(8, Value::Bytes(g.encode()));
        }
        v
    }

    pub fn encode(&self) -> Vec<u8> {
        cbor::encode(&self.to_value())
    }

    pub fn hash(&self) -> ObjectRef {
        hash_object(ObjectType::Certificate, &self.encode())
    }

    /// The short-lived key's KeyId: what its signatures name.
    pub fn key_id(&self) -> KeyId {
        self.key.hash()
    }

    pub fn decode(b: &[u8]) -> Result<Certificate, ObjectError> {
        let v = cbor::decode(b)?;
        let m = map(&v, "certificate")?;
        check_version(m)?;
        let key = Identity::decode(bytes(field(m, 1, "key")?, "key")?)?;
        let mut claims = Vec::new();
        for c in array(field(m, 4, "claims")?, "claims")? {
            let pair = array(c, "claim")?;
            if pair.len() != 2 {
                return Err(ObjectError::Schema("claim: expected [name, value]".into()));
            }
            claims.push((
                text(&pair[0], "claim name")?.to_owned(),
                text(&pair[1], "claim value")?.to_owned(),
            ));
        }
        let mut scope = Scope::NONE;
        for n in array(field(m, 5, "scope")?, "scope")? {
            let n = text(n, "scope")?;
            scope = scope
                | Scope::named(n).ok_or_else(|| {
                    ObjectError::Schema(format!("certificate: unknown scope {n:?}"))
                })?;
        }
        Ok(Certificate {
            key,
            issuer: oref(field(m, 2, "issuer")?, "issuer")?,
            subject: text(field(m, 3, "subject")?, "subject")?.to_owned(),
            claims,
            scope,
            not_before: uint(field(m, 6, "not_before")?, "not_before")?,
            expires: uint(field(m, 7, "expires")?, "expires")?,
            grant: match m.get(&8) {
                Some(g) => Some(
                    SignedGrant::decode(bytes(g, "grant")?)
                        .map_err(|e| ObjectError::Schema(format!("grant: {e}")))?,
                ),
                None => None,
            },
        })
    }

    /// Whether the key may sign within `scope` at `at_ms`, a time the
    /// signer did not choose.
    pub fn covers(&self, scope: Scope, at_ms: u64) -> bool {
        !scope.is_empty()
            && self.scope.has(scope)
            && self.not_before <= at_ms
            && at_ms <= self.expires
    }

    /// The claim called `name`, if the certificate has one.
    pub fn claim(&self, name: &str) -> Option<&str> {
        self.claims
            .iter()
            .find(|(k, _)| k == name)
            .map(|(_, v)| v.as_str())
    }
}

/// An author's grant (spec §14.7): it lets the keys an issuer certifies
/// for `subject` act for the author, as a delegate does, without a key of
/// their own. An agent's fresh keys then sign and seal changes in the
/// author's name while the grant lasts; the grant travels inside their
/// certificates, so a verifier needs nothing else. Signed by the author.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Grant {
    /// The author's KeyId, which signs the grant.
    pub grantor: KeyId,
    /// The subject whose certified keys act for it: `agent:NAME@ACCOUNT`.
    pub subject: String,
    /// The issuer whose certificates count.
    pub issuer: KeyId,
    /// What they may do for the author: changes, seal.
    pub scope: Scope,
    /// Valid from and until, in wall milliseconds.
    pub not_before: u64,
    pub expires: u64,
}

impl Grant {
    pub fn to_value(&self) -> Value {
        Value::map([
            (0, Value::Uint(1)),
            (1, Value::Bytes(self.grantor.0.to_vec())),
            (2, Value::Text(self.subject.clone())),
            (3, Value::Bytes(self.issuer.0.to_vec())),
            (
                4,
                Value::Array(
                    self.scope
                        .names()
                        .into_iter()
                        .map(|n| Value::Text(n.to_string()))
                        .collect(),
                ),
            ),
            (5, Value::Uint(self.not_before)),
            (6, Value::Uint(self.expires)),
        ])
    }

    pub fn encode(&self) -> Vec<u8> {
        cbor::encode(&self.to_value())
    }

    pub fn hash(&self) -> ObjectRef {
        hash_object(ObjectType::Grant, &self.encode())
    }

    pub fn decode(b: &[u8]) -> Result<Grant, ObjectError> {
        let v = cbor::decode(b)?;
        let m = map(&v, "grant")?;
        check_version(m)?;
        let mut scope = Scope::NONE;
        for n in array(field(m, 4, "scope")?, "scope")? {
            let n = text(n, "scope")?;
            scope = scope
                | Scope::named(n)
                    .ok_or_else(|| ObjectError::Schema(format!("grant: unknown scope {n:?}")))?;
        }
        Ok(Grant {
            grantor: oref(field(m, 1, "grantor")?, "grantor")?,
            subject: text(field(m, 2, "subject")?, "subject")?.to_owned(),
            issuer: oref(field(m, 3, "issuer")?, "issuer")?,
            scope,
            not_before: uint(field(m, 5, "not_before")?, "not_before")?,
            expires: uint(field(m, 6, "expires")?, "expires")?,
        })
    }

    /// Whether it lets its subject do `scope` for the author at `at_ms`
    /// (the change's own time, as for a delegation).
    pub fn covers(&self, scope: Scope, at_ms: u64) -> bool {
        !scope.is_empty()
            && self.scope.has(scope)
            && self.not_before <= at_ms
            && at_ms <= self.expires
    }
}

/// A grant with its author's signature over its ObjectRef.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct SignedGrant {
    pub grant: Grant,
    pub sig: Signature,
}

impl SignedGrant {
    /// Grant `grant`, signed by the author `grantor` holds the secret of.
    pub fn sign(grant: Grant, grantor: &Identity, sk: &SecretKey) -> SignedGrant {
        let sig = sk.sign(Domain::Grant, &grantor.hash(), &grant.hash());
        SignedGrant { grant, sig }
    }

    /// Signed by `grantor`, which it names, and well formed.
    pub fn verify(&self, grantor: &Identity) -> Result<(), CertError> {
        let g = &self.grant;
        if grantor.hash() != g.grantor || self.sig.key != g.grantor {
            return Err(CertError::WrongIssuer(g.grantor.short(12)));
        }
        verify(grantor, &self.sig, Domain::Grant, &g.hash())
            .map_err(|e| CertError::BadSignature(e.to_string()))?;
        if g.expires <= g.not_before {
            return Err(CertError::BadLifetime);
        }
        if g.scope.is_empty() {
            return Err(CertError::NoScope);
        }
        Ok(())
    }

    /// `[grant bytes, signature]`.
    pub fn encode(&self) -> Vec<u8> {
        cbor::encode(&Value::Array(vec![
            Value::Bytes(self.grant.encode()),
            self.sig.to_value(),
        ]))
    }

    pub fn decode(b: &[u8]) -> Result<SignedGrant, CertError> {
        let v = cbor::decode(b).map_err(ObjectError::from)?;
        let a = array(&v, "signed grant")?;
        if a.len() != 2 {
            return Err(CertError::Schema(
                "signed grant: expected [grant, signature]".into(),
            ));
        }
        Ok(SignedGrant {
            grant: Grant::decode(bytes(&a[0], "grant")?)?,
            sig: Signature::from_value(&a[1])?,
        })
    }
}

/// What a fresh key signs (a challenge, §14.3) to show its holder asks for
/// the certificate: bound to the credential it is asked with, so the
/// proof cannot be replayed with another.
pub fn certify_challenge(credential: &str) -> Vec<u8> {
    let mut c = b"oxy1 certify ".to_vec();
    c.extend_from_slice(blake3::hash(credential.as_bytes()).as_bytes());
    c
}

#[derive(Clone, Debug, PartialEq, Eq, thiserror::Error)]
pub enum CertError {
    #[error("the certificate names issuer {0}, not this one")]
    WrongIssuer(String),
    #[error("the issuer's signature does not verify: {0}")]
    BadSignature(String),
    #[error("the certificate is valid for no time, or for longer than an hour")]
    BadLifetime,
    #[error("the certificate gives no scope")]
    NoScope,
    #[error("{0}")]
    Schema(String),
}

impl From<ObjectError> for CertError {
    fn from(e: ObjectError) -> Self {
        CertError::Schema(e.to_string())
    }
}

/// A certificate with its issuer's signature over its ObjectRef.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct SignedCertificate {
    pub cert: Certificate,
    pub sig: Signature,
}

impl SignedCertificate {
    /// Issue `cert`, signed by the issuer `issuer` holds the secret of.
    pub fn sign(mut cert: Certificate, issuer: &Identity, sk: &SecretKey) -> SignedCertificate {
        // Claims in their canonical order, as encoded.
        cert.claims.sort();
        let sig = sk.sign(Domain::Certificate, &issuer.hash(), &cert.hash());
        SignedCertificate { cert, sig }
    }

    /// Signed by `issuer`, which it names, and well formed. Whether to
    /// trust the issuer for its subject is the policy's question.
    pub fn verify(&self, issuer: &Identity) -> Result<(), CertError> {
        let c = &self.cert;
        if issuer.hash() != c.issuer || self.sig.key != c.issuer {
            return Err(CertError::WrongIssuer(c.issuer.short(12)));
        }
        verify(issuer, &self.sig, Domain::Certificate, &c.hash())
            .map_err(|e| CertError::BadSignature(e.to_string()))?;
        if c.expires <= c.not_before || c.expires - c.not_before > MAX_LIFETIME_MS {
            return Err(CertError::BadLifetime);
        }
        if c.scope.is_empty() {
            return Err(CertError::NoScope);
        }
        Ok(())
    }

    /// `[certificate bytes, signature]`.
    pub fn encode(&self) -> Vec<u8> {
        cbor::encode(&Value::Array(vec![
            Value::Bytes(self.cert.encode()),
            self.sig.to_value(),
        ]))
    }

    pub fn decode(b: &[u8]) -> Result<SignedCertificate, CertError> {
        let v = cbor::decode(b).map_err(ObjectError::from)?;
        let a = array(&v, "signed certificate")?;
        if a.len() != 2 {
            return Err(CertError::Schema(
                "signed certificate: expected [certificate, signature]".into(),
            ));
        }
        Ok(SignedCertificate {
            cert: Certificate::decode(bytes(&a[0], "certificate")?)?,
            sig: Signature::from_value(&a[1])?,
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn issue(
        issuer_sk: &SecretKey,
        issuer: &Identity,
        minutes: u64,
    ) -> (SecretKey, SignedCertificate) {
        let job_sk = SecretKey::generate();
        let cert = Certificate {
            key: job_sk.identity("job 12 build", "[email protected]", 1_000),
            issuer: issuer.hash(),
            subject: "repo:andy/demo:bookmark:main".into(),
            claims: vec![
                ("run".into(), "12".into()),
                ("environment".into(), "prod".into()),
            ],
            scope: Scope::CHANGES | Scope::REFS,
            not_before: 1_000,
            expires: 1_000 + minutes * 60_000,
            grant: None,
        };
        (job_sk, SignedCertificate::sign(cert, issuer, issuer_sk))
    }

    #[test]
    fn a_certificate_round_trips_and_verifies_with_its_issuer_only() {
        let hub_sk = SecretKey::generate();
        let hub = hub_sk.identity("oxygenhub.io", "[email protected]", 1);
        let (_, sc) = issue(&hub_sk, &hub, 10);
        let back = SignedCertificate::decode(&sc.encode()).unwrap();
        assert_eq!(back, sc);
        assert_eq!(back.cert.claims[0].0, "environment", "claims kept sorted");
        assert_eq!(back.cert.claim("run"), Some("12"));
        assert!(back.verify(&hub).is_ok());
        let other_sk = SecretKey::generate();
        let other = other_sk.identity("elsewhere", "[email protected]", 1);
        assert!(matches!(
            back.verify(&other),
            Err(CertError::WrongIssuer(_))
        ));
        // Changed after signing: the signature no longer covers it.
        let mut forged = back.clone();
        forged.cert.subject = "repo:andy/demo:bookmark:release".into();
        assert!(matches!(
            forged.verify(&hub),
            Err(CertError::BadSignature(_))
        ));
        // Signed by another key in the issuer's name.
        let mut stolen = back.clone();
        stolen.sig = other_sk.sign(Domain::Certificate, &hub.hash(), &back.cert.hash());
        assert!(matches!(
            stolen.verify(&hub),
            Err(CertError::BadSignature(_))
        ));
    }

    #[test]
    fn a_grant_rides_in_its_certificate_and_verifies_with_its_author_only() {
        let hub_sk = SecretKey::generate();
        let hub = hub_sk.identity("oxygenhub.io", "[email protected]", 1);
        let ada_sk = SecretKey::generate();
        let ada = ada_sk.identity("Ada", "[email protected]", 1);
        let g = SignedGrant::sign(
            Grant {
                grantor: ada.hash(),
                subject: "agent:claude@ada".into(),
                issuer: hub.hash(),
                scope: Scope::CHANGES | Scope::SEAL,
                not_before: 1_000,
                expires: 2_000,
            },
            &ada,
            &ada_sk,
        );
        assert!(g.verify(&ada).is_ok());
        assert!(g.verify(&hub).is_err(), "only its author's");
        assert!(g.grant.covers(Scope::SEAL, 1_500));
        assert!(!g.grant.covers(Scope::REFS, 1_500));
        assert!(!g.grant.covers(Scope::SEAL, 2_001));
        let (_, plain) = issue(&hub_sk, &hub, 10);
        assert!(
            !matches!(cbor::decode(&plain.cert.encode()).unwrap(), Value::Map(m) if m.contains_key(&8)),
            "no grant, no field 8"
        );
        let mut with = plain.cert.clone();
        with.grant = Some(g.clone());
        let sc = SignedCertificate::sign(with, &hub, &hub_sk);
        let back = SignedCertificate::decode(&sc.encode()).unwrap();
        assert_eq!(back.cert.grant, Some(g));
        assert!(back.verify(&hub).is_ok());
        assert_ne!(back.cert.hash(), plain.cert.hash());
    }

    #[test]
    fn it_covers_its_scope_and_window_only() {
        let hub_sk = SecretKey::generate();
        let hub = hub_sk.identity("oxygenhub.io", "[email protected]", 1);
        let (_, sc) = issue(&hub_sk, &hub, 10);
        let c = &sc.cert;
        assert!(c.covers(Scope::CHANGES, 1_000) && c.covers(Scope::REFS, 1_000 + 10 * 60_000));
        assert!(!c.covers(Scope::SEAL, 2_000), "not a scope it gives");
        assert!(!c.covers(Scope::CHANGES, 999), "before it");
        assert!(
            !c.covers(Scope::CHANGES, 1_000 + 10 * 60_000 + 1),
            "after it"
        );
        assert!(!c.covers(Scope::NONE, 2_000));
        let (_, long) = issue(&hub_sk, &hub, 61);
        assert_eq!(long.verify(&hub), Err(CertError::BadLifetime));
    }

    #[test]
    fn the_proof_of_possession_is_bound_to_its_credential() {
        let sk = SecretKey::generate();
        let id = sk.identity("job", "[email protected]", 1);
        let proof = sk
            .sign_challenge(&id.hash(), &certify_challenge("flowjob_aaa"))
            .unwrap();
        assert!(
            crate::identity::verify_challenge(&id, &proof, &certify_challenge("flowjob_aaa"))
                .is_ok()
        );
        assert!(
            crate::identity::verify_challenge(&id, &proof, &certify_challenge("flowjob_bbb"))
                .is_err()
        );
    }

    #[test]
    fn a_signature_by_the_short_lived_key_names_it() {
        let hub_sk = SecretKey::generate();
        let hub = hub_sk.identity("oxygenhub.io", "[email protected]", 1);
        let (job_sk, sc) = issue(&hub_sk, &hub, 10);
        let target = ObjectRef([5; 32]);
        let sig = job_sk.sign(Domain::Change, &sc.cert.key_id(), &target);
        assert_eq!(sig.key, sc.cert.key_id());
        assert!(verify(&sc.cert.key, &sig, Domain::Change, &target).is_ok());
    }
}

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1		//! Certificates for short-lived keys (spec §14.7, oxygenhub#241,
2		//! oxygenhub docs/keyless.md). An issuer, a hub's key, binds a fresh key
3		//! to the identity that proved itself (an OIDC subject) for minutes: a Flow
4		//! job or an agent signs with that key and throws it away. The certificate
5		//! is signed with the issuer's composite key, so it is post-quantum like
6		//! every other signature in Oxygen.
7		//!
8		//! Whether to trust an issuer, and for which subjects, is the trust
9		//! policy's (§14.5); whether a signature was made inside the certificate's
10		//! window needs time the signer does not choose, which the caller passes
11		//! in (a host's acceptance now, the transparency log's later).
12
13		use crate::cbor::{self, Value};
14		use crate::hash::{hash_object, KeyId, ObjectRef, ObjectType};
15		use crate::identity::{verify, Domain, Identity, Scope, SecretKey, Signature};
16		use crate::objects::{array, bytes, check_version, field, map, oref, text, uint, ObjectError};
17
18		/// The longest a certificate may be valid. Jobs get ten minutes; an hour
19		/// leaves room for an issuer that rounds up, and no more.
20		pub const MAX_LIFETIME_MS: u64 = 60 * 60 * 1000;
21
22		#[derive(Clone, Debug, PartialEq, Eq)]
23		pub struct Certificate {
24		/// The short-lived key's public identity.
25		pub key: Identity,
26		/// The issuer's KeyId (a hub's key).
27		pub issuer: KeyId,
28		/// Who proved it: `repo:OWNER/NAME:bookmark:B`, `agent:NAME@ACCOUNT`.
29		pub subject: String,
30		/// What else the proof said (environment, run, job), sorted by name.
31		pub claims: Vec<(String, String)>,
32		/// What the key may sign: changes, refs, seals.
33		pub scope: Scope,
34		/// Valid from and until, in wall milliseconds.
35		pub not_before: u64,
36		pub expires: u64,
37		/// The grant that lets the subject act for an author, when an agent
38		/// asked with one (field 8, only when present).
39		pub grant: Option<SignedGrant>,
40		}
41
42		impl Certificate {
43	110×	pub fn to_value(&self) -> Value {
44	110×	let mut claims = self.claims.clone();
45	110×	claims.sort();
46	110×	let mut v = Value::map([
47	110×	(0, Value::Uint(1)),
48	110×	(1, Value::Bytes(self.key.encode())),
49	110×	(2, Value::Bytes(self.issuer.0.to_vec())),
50	110×	(3, Value::Text(self.subject.clone())),
51		(
52		4,
53		Value::Array(
54	110×	claims
55	110×	.into_iter()
56	110×	.map(\|(k, v)\| Value::Array(vec![Value::Text(k), Value::Text(v)]))
57	110×	.collect(),
58		),
59		),
60		(
61		5,
62		Value::Array(
63	110×	self.scope
64	110×	.names()
65	110×	.into_iter()
66	247×	.map(\|n\| Value::Text(n.to_string()))
67	110×	.collect(),
68		),
69		),
70	110×	(6, Value::Uint(self.not_before)),
71	110×	(7, Value::Uint(self.expires)),
72		]);
73	110×	if let (Some(g), Value::Map(m)) = (&self.grant, &mut v) {
74	42×	m.insert(8, Value::Bytes(g.encode()));
75	68×	}
76	110×	v
77	110×	}
78
79	110×	pub fn encode(&self) -> Vec<u8> {
80	110×	cbor::encode(&self.to_value())
81	110×	}
82
83	83×	pub fn hash(&self) -> ObjectRef {
84	83×	hash_object(ObjectType::Certificate, &self.encode())
85	83×	}
86
87		/// The short-lived key's KeyId: what its signatures name.
88	44×	pub fn key_id(&self) -> KeyId {
89	44×	self.key.hash()
90	44×	}
91
92	66×	pub fn decode(b: &[u8]) -> Result<Certificate, ObjectError> {
93	66×	let v = cbor::decode(b)?;
94	66×	let m = map(&v, "certificate")?;
95	66×	check_version(m)?;
96	66×	let key = Identity::decode(bytes(field(m, 1, "key")?, "key")?)?;
97	66×	let mut claims = Vec::new();
98	66×	for c in array(field(m, 4, "claims")?, "claims")? {
99	5×	let pair = array(c, "claim")?;
100	5×	if pair.len() != 2 {
101	0×	return Err(ObjectError::Schema("claim: expected [name, value]".into()));
102	5×	}
103	5×	claims.push((
104	5×	text(&pair[0], "claim name")?.to_owned(),
105	5×	text(&pair[1], "claim value")?.to_owned(),
106		));
107		}
108	66×	let mut scope = Scope::NONE;
109	155×	for n in array(field(m, 5, "scope")?, "scope")? {
110	155×	let n = text(n, "scope")?;
111	155×	scope = scope
112	155×	\| Scope::named(n).ok_or_else(\|\| {
113	0×	ObjectError::Schema(format!("certificate: unknown scope {n:?}"))
114	0×	})?;
115		}
116		Ok(Certificate {
117	66×	key,
118	66×	issuer: oref(field(m, 2, "issuer")?, "issuer")?,
119	66×	subject: text(field(m, 3, "subject")?, "subject")?.to_owned(),
120	66×	claims,
121	66×	scope,
122	66×	not_before: uint(field(m, 6, "not_before")?, "not_before")?,
123	66×	expires: uint(field(m, 7, "expires")?, "expires")?,
124	66×	grant: match m.get(&8) {
125	27×	Some(g) => Some(
126	27×	SignedGrant::decode(bytes(g, "grant")?)
127	27×	.map_err(\|e\| ObjectError::Schema(format!("grant: {e}")))?,
128		),
129	39×	None => None,
130		},
131		})
132	66×	}
133
134		/// Whether the key may sign within `scope` at `at_ms`, a time the
135		/// signer did not choose.
136	25×	pub fn covers(&self, scope: Scope, at_ms: u64) -> bool {
137	25×	!scope.is_empty()
138	24×	&& self.scope.has(scope)
139	22×	&& self.not_before <= at_ms
140	21×	&& at_ms <= self.expires
141	25×	}
142
143		/// The claim called `name`, if the certificate has one.
144	1×	pub fn claim(&self, name: &str) -> Option<&str> {
145	1×	self.claims
146	1×	.iter()
147	2×	.find(\|(k, _)\| k == name)
148	1×	.map(\|(_, v)\| v.as_str())
149	1×	}
150		}
151
152		/// An author's grant (spec §14.7): it lets the keys an issuer certifies
153		/// for `subject` act for the author, as a delegate does, without a key of
154		/// their own. An agent's fresh keys then sign and seal changes in the
155		/// author's name while the grant lasts; the grant travels inside their
156		/// certificates, so a verifier needs nothing else. Signed by the author.
157		#[derive(Clone, Debug, PartialEq, Eq)]
158		pub struct Grant {
159		/// The author's KeyId, which signs the grant.
160		pub grantor: KeyId,
161		/// The subject whose certified keys act for it: `agent:NAME@ACCOUNT`.
162		pub subject: String,
163		/// The issuer whose certificates count.
164		pub issuer: KeyId,
165		/// What they may do for the author: changes, seal.
166		pub scope: Scope,
167		/// Valid from and until, in wall milliseconds.
168		pub not_before: u64,
169		pub expires: u64,
170		}
171
172		impl Grant {
173	53×	pub fn to_value(&self) -> Value {
174	53×	Value::map([
175	53×	(0, Value::Uint(1)),
176	53×	(1, Value::Bytes(self.grantor.0.to_vec())),
177	53×	(2, Value::Text(self.subject.clone())),
178	53×	(3, Value::Bytes(self.issuer.0.to_vec())),
179		(
180		4,
181		Value::Array(
182	53×	self.scope
183	53×	.names()
184	53×	.into_iter()
185	106×	.map(\|n\| Value::Text(n.to_string()))
186	53×	.collect(),
187		),
188		),
189	53×	(5, Value::Uint(self.not_before)),
190	53×	(6, Value::Uint(self.expires)),
191		])
192	53×	}
193
194	53×	pub fn encode(&self) -> Vec<u8> {
195	53×	cbor::encode(&self.to_value())
196	53×	}
197
198	11×	pub fn hash(&self) -> ObjectRef {
199	11×	hash_object(ObjectType::Grant, &self.encode())
200	11×	}
201
202	27×	pub fn decode(b: &[u8]) -> Result<Grant, ObjectError> {
203	27×	let v = cbor::decode(b)?;
204	27×	let m = map(&v, "grant")?;
205	27×	check_version(m)?;
206	27×	let mut scope = Scope::NONE;
207	54×	for n in array(field(m, 4, "scope")?, "scope")? {
208	54×	let n = text(n, "scope")?;
209	54×	scope = scope
210	54×	\| Scope::named(n)
211	54×	.ok_or_else(\|\| ObjectError::Schema(format!("grant: unknown scope {n:?}")))?;
212		}
213		Ok(Grant {
214	27×	grantor: oref(field(m, 1, "grantor")?, "grantor")?,
215	27×	subject: text(field(m, 2, "subject")?, "subject")?.to_owned(),
216	27×	issuer: oref(field(m, 3, "issuer")?, "issuer")?,
217	27×	scope,
218	27×	not_before: uint(field(m, 5, "not_before")?, "not_before")?,
219	27×	expires: uint(field(m, 6, "expires")?, "expires")?,
220		})
221	27×	}
222
223		/// Whether it lets its subject do `scope` for the author at `at_ms`
224		/// (the change's own time, as for a delegation).
225	9×	pub fn covers(&self, scope: Scope, at_ms: u64) -> bool {
226	9×	!scope.is_empty()
227	9×	&& self.scope.has(scope)
228	8×	&& self.not_before <= at_ms
229	8×	&& at_ms <= self.expires
230	9×	}
231		}
232
233		/// A grant with its author's signature over its ObjectRef.
234		#[derive(Clone, Debug, PartialEq, Eq)]
235		pub struct SignedGrant {
236		pub grant: Grant,
237		pub sig: Signature,
238		}
239
240		impl SignedGrant {
241		/// Grant `grant`, signed by the author `grantor` holds the secret of.
242	4×	pub fn sign(grant: Grant, grantor: &Identity, sk: &SecretKey) -> SignedGrant {
243	4×	let sig = sk.sign(Domain::Grant, &grantor.hash(), &grant.hash());
244	4×	SignedGrant { grant, sig }
245	4×	}
246
247		/// Signed by `grantor`, which it names, and well formed.
248	8×	pub fn verify(&self, grantor: &Identity) -> Result<(), CertError> {
249	8×	let g = &self.grant;
250	8×	if grantor.hash() != g.grantor \|\| self.sig.key != g.grantor {
251	1×	return Err(CertError::WrongIssuer(g.grantor.short(12)));
252	7×	}
253	7×	verify(grantor, &self.sig, Domain::Grant, &g.hash())
254	7×	.map_err(\|e\| CertError::BadSignature(e.to_string()))?;
255	7×	if g.expires <= g.not_before {
256	0×	return Err(CertError::BadLifetime);
257	7×	}
258	7×	if g.scope.is_empty() {
259	0×	return Err(CertError::NoScope);
260	7×	}
261	7×	Ok(())
262	8×	}
263
264		/// `[grant bytes, signature]`.
265	42×	pub fn encode(&self) -> Vec<u8> {
266	42×	cbor::encode(&Value::Array(vec![
267	42×	Value::Bytes(self.grant.encode()),
268	42×	self.sig.to_value(),
269	42×	]))
270	42×	}
271
272	27×	pub fn decode(b: &[u8]) -> Result<SignedGrant, CertError> {
273	27×	let v = cbor::decode(b).map_err(ObjectError::from)?;
274	27×	let a = array(&v, "signed grant")?;
275	27×	if a.len() != 2 {
276	0×	return Err(CertError::Schema(
277	0×	"signed grant: expected [grant, signature]".into(),
278	0×	));
279	27×	}
280		Ok(SignedGrant {
281	27×	grant: Grant::decode(bytes(&a[0], "grant")?)?,
282	27×	sig: Signature::from_value(&a[1])?,
283		})
284	27×	}
285		}
286
287		/// What a fresh key signs (a challenge, §14.3) to show its holder asks for
288		/// the certificate: bound to the credential it is asked with, so the
289		/// proof cannot be replayed with another.
290	3×	pub fn certify_challenge(credential: &str) -> Vec<u8> {
291	3×	let mut c = b"oxy1 certify ".to_vec();
292	3×	c.extend_from_slice(blake3::hash(credential.as_bytes()).as_bytes());
293	3×	c
294	3×	}
295
296		#[derive(Clone, Debug, PartialEq, Eq, thiserror::Error)]
297		pub enum CertError {
298		#[error("the certificate names issuer {0}, not this one")]
299		WrongIssuer(String),
300		#[error("the issuer's signature does not verify: {0}")]
301		BadSignature(String),
302		#[error("the certificate is valid for no time, or for longer than an hour")]
303		BadLifetime,
304		#[error("the certificate gives no scope")]
305		NoScope,
306		#[error("{0}")]
307		Schema(String),
308		}
309
310		impl From<ObjectError> for CertError {
311	0×	fn from(e: ObjectError) -> Self {
312	0×	CertError::Schema(e.to_string())
313	0×	}
314		}
315
316		/// A certificate with its issuer's signature over its ObjectRef.
317		#[derive(Clone, Debug, PartialEq, Eq)]
318		pub struct SignedCertificate {
319		pub cert: Certificate,
320		pub sig: Signature,
321		}
322
323		impl SignedCertificate {
324		/// Issue `cert`, signed by the issuer `issuer` holds the secret of.
325	20×	pub fn sign(mut cert: Certificate, issuer: &Identity, sk: &SecretKey) -> SignedCertificate {
326		// Claims in their canonical order, as encoded.
327	20×	cert.claims.sort();
328	20×	let sig = sk.sign(Domain::Certificate, &issuer.hash(), &cert.hash());
329	20×	SignedCertificate { cert, sig }
330	20×	}
331
332		/// Signed by `issuer`, which it names, and well formed. Whether to
333		/// trust the issuer for its subject is the policy's question.
334	48×	pub fn verify(&self, issuer: &Identity) -> Result<(), CertError> {
335	48×	let c = &self.cert;
336	48×	if issuer.hash() != c.issuer \|\| self.sig.key != c.issuer {
337	2×	return Err(CertError::WrongIssuer(c.issuer.short(12)));
338	46×	}
339	46×	verify(issuer, &self.sig, Domain::Certificate, &c.hash())
340	46×	.map_err(\|e\| CertError::BadSignature(e.to_string()))?;
341	44×	if c.expires <= c.not_before \|\| c.expires - c.not_before > MAX_LIFETIME_MS {
342	1×	return Err(CertError::BadLifetime);
343	43×	}
344	43×	if c.scope.is_empty() {
345	0×	return Err(CertError::NoScope);
346	43×	}
347	43×	Ok(())
348	48×	}
349
350		/// `[certificate bytes, signature]`.
351	4×	pub fn encode(&self) -> Vec<u8> {
352	4×	cbor::encode(&Value::Array(vec![
353	4×	Value::Bytes(self.cert.encode()),
354	4×	self.sig.to_value(),
355	4×	]))
356	4×	}
357
358	4×	pub fn decode(b: &[u8]) -> Result<SignedCertificate, CertError> {
359	4×	let v = cbor::decode(b).map_err(ObjectError::from)?;
360	4×	let a = array(&v, "signed certificate")?;
361	4×	if a.len() != 2 {
362	0×	return Err(CertError::Schema(
363	0×	"signed certificate: expected [certificate, signature]".into(),
364	0×	));
365	4×	}
366		Ok(SignedCertificate {
367	4×	cert: Certificate::decode(bytes(&a[0], "certificate")?)?,
368	4×	sig: Signature::from_value(&a[1])?,
369		})
370	4×	}
371		}
372
373		#[cfg(test)]
374		mod tests {
375		use super::*;
376
377	5×	fn issue(
378	5×	issuer_sk: &SecretKey,
379	5×	issuer: &Identity,
380	5×	minutes: u64,
381	5×	) -> (SecretKey, SignedCertificate) {
382	5×	let job_sk = SecretKey::generate();
383	5×	let cert = Certificate {
384	5×	key: job_sk.identity("job 12 build", "[email protected]", 1_000),
385	5×	issuer: issuer.hash(),
386	5×	subject: "repo:andy/demo:bookmark:main".into(),
387	5×	claims: vec![
388	5×	("run".into(), "12".into()),
389	5×	("environment".into(), "prod".into()),
390	5×	],
391	5×	scope: Scope::CHANGES \| Scope::REFS,
392	5×	not_before: 1_000,
393	5×	expires: 1_000 + minutes * 60_000,
394	5×	grant: None,
395	5×	};
396	5×	(job_sk, SignedCertificate::sign(cert, issuer, issuer_sk))
397	5×	}
398
399		#[test]
400	1×	fn a_certificate_round_trips_and_verifies_with_its_issuer_only() {
401	1×	let hub_sk = SecretKey::generate();
402	1×	let hub = hub_sk.identity("oxygenhub.io", "[email protected]", 1);
403	1×	let (_, sc) = issue(&hub_sk, &hub, 10);
404	1×	let back = SignedCertificate::decode(&sc.encode()).unwrap();
405	1×	assert_eq!(back, sc);
406	1×	assert_eq!(back.cert.claims[0].0, "environment", "claims kept sorted");
407	1×	assert_eq!(back.cert.claim("run"), Some("12"));
408	1×	assert!(back.verify(&hub).is_ok());
409	1×	let other_sk = SecretKey::generate();
410	1×	let other = other_sk.identity("elsewhere", "[email protected]", 1);
411	1×	assert!(matches!(
412	1×	back.verify(&other),
413		Err(CertError::WrongIssuer(_))
414		));
415		// Changed after signing: the signature no longer covers it.
416	1×	let mut forged = back.clone();
417	1×	forged.cert.subject = "repo:andy/demo:bookmark:release".into();
418	1×	assert!(matches!(
419	1×	forged.verify(&hub),
420		Err(CertError::BadSignature(_))
421		));
422		// Signed by another key in the issuer's name.
423	1×	let mut stolen = back.clone();
424	1×	stolen.sig = other_sk.sign(Domain::Certificate, &hub.hash(), &back.cert.hash());
425	1×	assert!(matches!(
426	1×	stolen.verify(&hub),
427		Err(CertError::BadSignature(_))
428		));
429	1×	}
430
431		#[test]
432	1×	fn a_grant_rides_in_its_certificate_and_verifies_with_its_author_only() {
433	1×	let hub_sk = SecretKey::generate();
434	1×	let hub = hub_sk.identity("oxygenhub.io", "[email protected]", 1);
435	1×	let ada_sk = SecretKey::generate();
436	1×	let ada = ada_sk.identity("Ada", "[email protected]", 1);
437	1×	let g = SignedGrant::sign(
438	1×	Grant {
439	1×	grantor: ada.hash(),
440	1×	subject: "agent:claude@ada".into(),
441	1×	issuer: hub.hash(),
442	1×	scope: Scope::CHANGES \| Scope::SEAL,
443	1×	not_before: 1_000,
444	1×	expires: 2_000,
445	1×	},
446	1×	&ada,
447	1×	&ada_sk,
448		);
449	1×	assert!(g.verify(&ada).is_ok());
450	1×	assert!(g.verify(&hub).is_err(), "only its author's");
451	1×	assert!(g.grant.covers(Scope::SEAL, 1_500));
452	1×	assert!(!g.grant.covers(Scope::REFS, 1_500));
453	1×	assert!(!g.grant.covers(Scope::SEAL, 2_001));
454	1×	let (_, plain) = issue(&hub_sk, &hub, 10);
455	1×	assert!(
456	1×	!matches!(cbor::decode(&plain.cert.encode()).unwrap(), Value::Map(m) if m.contains_key(&8)),
457		"no grant, no field 8"
458		);
459	1×	let mut with = plain.cert.clone();
460	1×	with.grant = Some(g.clone());
461	1×	let sc = SignedCertificate::sign(with, &hub, &hub_sk);
462	1×	let back = SignedCertificate::decode(&sc.encode()).unwrap();
463	1×	assert_eq!(back.cert.grant, Some(g));
464	1×	assert!(back.verify(&hub).is_ok());
465	1×	assert_ne!(back.cert.hash(), plain.cert.hash());
466	1×	}
467
468		#[test]
469	1×	fn it_covers_its_scope_and_window_only() {
470	1×	let hub_sk = SecretKey::generate();
471	1×	let hub = hub_sk.identity("oxygenhub.io", "[email protected]", 1);
472	1×	let (_, sc) = issue(&hub_sk, &hub, 10);
473	1×	let c = &sc.cert;
474	1×	assert!(c.covers(Scope::CHANGES, 1_000) && c.covers(Scope::REFS, 1_000 + 10 * 60_000));
475	1×	assert!(!c.covers(Scope::SEAL, 2_000), "not a scope it gives");
476	1×	assert!(!c.covers(Scope::CHANGES, 999), "before it");
477	1×	assert!(
478	1×	!c.covers(Scope::CHANGES, 1_000 + 10 * 60_000 + 1),
479		"after it"
480		);
481	1×	assert!(!c.covers(Scope::NONE, 2_000));
482	1×	let (_, long) = issue(&hub_sk, &hub, 61);
483	1×	assert_eq!(long.verify(&hub), Err(CertError::BadLifetime));
484	1×	}
485
486		#[test]
487	1×	fn the_proof_of_possession_is_bound_to_its_credential() {
488	1×	let sk = SecretKey::generate();
489	1×	let id = sk.identity("job", "[email protected]", 1);
490	1×	let proof = sk
491	1×	.sign_challenge(&id.hash(), &certify_challenge("flowjob_aaa"))
492	1×	.unwrap();
493	1×	assert!(
494	1×	crate::identity::verify_challenge(&id, &proof, &certify_challenge("flowjob_aaa"))
495	1×	.is_ok()
496		);
497	1×	assert!(
498	1×	crate::identity::verify_challenge(&id, &proof, &certify_challenge("flowjob_bbb"))
499	1×	.is_err()
500		);
501	1×	}
502
503		#[test]
504	1×	fn a_signature_by_the_short_lived_key_names_it() {
505	1×	let hub_sk = SecretKey::generate();
506	1×	let hub = hub_sk.identity("oxygenhub.io", "[email protected]", 1);
507	1×	let (job_sk, sc) = issue(&hub_sk, &hub, 10);
508	1×	let target = ObjectRef([5; 32]);
509	1×	let sig = job_sk.sign(Domain::Change, &sc.cert.key_id(), &target);
510	1×	assert_eq!(sig.key, sc.cert.key_id());
511	1×	assert!(verify(&sc.cert.key, &sig, Domain::Change, &target).is_ok());
512	1×	}
513		}

Coverage / crates/oxy-core/src/cert.rs 93.8%

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