triblespace_core/repo/
commit.rs

1use crate::macros::entity;
2use crate::macros::pattern;
3use crate::inline::TryToInline;
4use ed25519::Signature;
5use ed25519_dalek::SignatureError;
6use ed25519_dalek::SigningKey;
7use ed25519_dalek::Verifier;
8use ed25519_dalek::VerifyingKey;
9use itertools::Itertools;
10
11use ed25519::signature::Signer;
12
13use crate::blob::encodings::longstring::LongString;
14use crate::blob::encodings::simplearchive::SimpleArchive;
15use crate::blob::Blob;
16use crate::prelude::inlineencodings::Handle;
17use crate::query::find;
18use crate::trible::TribleSet;
19use crate::inline::Inline;
20
21use hifitime::Epoch;
22
23/// Error returned when commit signature verification fails.
24pub enum ValidationError {
25    /// The metadata contains multiple signature entities for the same commit.
26    AmbiguousSignature,
27    /// No signature information was found in the metadata.
28    MissingSignature,
29    /// The signature did not match the commit bytes or the public key was invalid.
30    FailedValidation,
31}
32
33impl From<SignatureError> for ValidationError {
34    /// Converts an Ed25519 signature error into a [`ValidationError::FailedValidation`].
35    fn from(_: SignatureError) -> Self {
36        ValidationError::FailedValidation
37    }
38}
39
40/// Constructs commit metadata describing `content`, optional `metadata`, and its parent commits.
41///
42/// The resulting [`TribleSet`] is signed using `signing_key` when content is
43/// present, so that its authenticity can later be verified. If `msg` is
44/// provided it is stored as a long commit message via a LongString blob
45/// handle. If `metadata` is provided it is stored as a SimpleArchive handle.
46///
47/// The commit's entity id is derived intrinsically from the
48/// `(attribute, value)` pairs present in the metadata — so two commits with
49/// identical content, parents, and signatures collide on entity id and blob
50/// hash alike. This matters especially for **merge commits**
51/// (`content = None`): merges carry no author-specific bits (no signature,
52/// no timestamp, no random entity id), so two peers merging the same parent
53/// set produce bit-identical merge commits, and parallel-merge scenarios
54/// converge in zero extra rounds.
55pub fn commit_metadata(
56    signing_key: &SigningKey,
57    parents: impl IntoIterator<Item = Inline<Handle<SimpleArchive>>>,
58    msg: Option<Inline<Handle<LongString>>>,
59    content: Option<Blob<SimpleArchive>>,
60    metadata: Option<Inline<Handle<SimpleArchive>>>,
61) -> TribleSet {
62    // Authored commits carry a timestamp and a signature. Merge commits
63    // (content = None) carry neither, so they stay content-deterministic.
64    let (content_handle, signed_by, signature, created_at) = match content.as_ref() {
65        Some(blob) => {
66            let now = Epoch::now().expect("system time");
67            let timestamp: Inline<_> =
68                (now, now).try_to_inline().expect("point interval");
69            (
70                Some(blob.get_handle()),
71                Some(signing_key.verifying_key()),
72                Some(signing_key.sign(&blob.bytes)),
73                Some(timestamp),
74            )
75        }
76        None => (None, None, None, None),
77    };
78    let parents: Vec<_> = parents.into_iter().collect();
79
80    // `entity!` without an explicit `id @` prefix derives the entity id
81    // by hashing the sorted/deduped (attr_id, value) pairs. The resulting
82    // commit is content-addressed at both the blob level (via
83    // SimpleArchive) and the entity-id level.
84    let fragment = entity! {
85        crate::metadata::created_at?: created_at,
86        super::content?: content_handle,
87        super::signed_by?: signed_by,
88        super::signature_r?: signature,
89        super::signature_s?: signature,
90        super::message?: msg,
91        super::metadata?: metadata,
92        super::parent*: parents,
93    };
94
95    fragment.into()
96}
97
98/// Validates that the `metadata` blob genuinely signs the supplied commit
99/// `content`.
100///
101/// Returns an error if the signature information is missing, malformed or does
102/// not match the commit bytes.
103pub fn verify(content: Blob<SimpleArchive>, metadata: TribleSet) -> Result<(), ValidationError> {
104    let handle = content.get_handle();
105    let (pubkey, r, s) = match find!(
106    (pubkey: Inline<_>, r, s),
107    pattern!(&metadata, [
108    {
109        super::content: handle,
110        super::signed_by: ?pubkey,
111        super::signature_r: ?r,
112        super::signature_s: ?s
113    }]))
114    .at_most_one()
115    {
116        Ok(Some(result)) => result,
117        Ok(None) => return Err(ValidationError::MissingSignature),
118        Err(_) => return Err(ValidationError::AmbiguousSignature),
119    };
120
121    let pubkey: VerifyingKey = pubkey.try_from_inline()?;
122    let signature = Signature::from_components(r, s);
123    pubkey.verify(&content.bytes, &signature)?;
124    Ok(())
125}
triblespace_core/repo/commit.rs

triblespace_core/repo/
commit.rs
