triblespace-core 0.33.0

use crate::macros::entity;
use crate::value::TryToValue;
use crate::macros::pattern;
use ed25519::Signature;
use ed25519_dalek::SignatureError;
use ed25519_dalek::SigningKey;
use ed25519_dalek::Verifier;
use ed25519_dalek::VerifyingKey;
use itertools::Itertools;

use ed25519::signature::Signer;

use crate::blob::schemas::longstring::LongString;
use crate::blob::schemas::simplearchive::SimpleArchive;
use crate::blob::Blob;
use crate::prelude::valueschemas::Handle;
use crate::query::find;
use crate::trible::TribleSet;
use crate::value::Value;

use crate::value::schemas::hash::Blake3;
use hifitime::Epoch;

/// Error returned when commit signature verification fails.
pub enum ValidationError {
    /// The metadata contains multiple signature entities for the same commit.
    AmbiguousSignature,
    /// No signature information was found in the metadata.
    MissingSignature,
    /// The signature did not match the commit bytes or the public key was invalid.
    FailedValidation,
}

impl From<SignatureError> for ValidationError {
    /// Converts an Ed25519 signature error into a [`ValidationError::FailedValidation`].
    fn from(_: SignatureError) -> Self {
        ValidationError::FailedValidation
    }
}

/// Constructs commit metadata describing `content`, optional `metadata`, and its parent commits.
///
/// The resulting [`TribleSet`] is signed using `signing_key` so that its
/// authenticity can later be verified. If `msg` is provided it is stored as a
/// long commit message via a LongString blob handle. If `metadata` is provided
/// it is stored as a SimpleArchive handle.
pub fn commit_metadata(
    signing_key: &SigningKey,
    parents: impl IntoIterator<Item = Value<Handle<Blake3, SimpleArchive>>>,
    msg: Option<Value<Handle<Blake3, LongString>>>,
    content: Option<Blob<SimpleArchive>>,
    metadata: Option<Value<Handle<Blake3, SimpleArchive>>>,
) -> TribleSet {
    let mut commit = TribleSet::new();
    let commit_entity = crate::id::rngid();
    let now = Epoch::now().expect("system time");

    commit += entity! { &commit_entity @  crate::metadata::created_at: (now, now).try_to_value().expect("point interval")  };

    if let Some(content) = content {
        let handle = content.get_handle();
        let signature = signing_key.sign(&content.bytes);

        commit += entity! { &commit_entity @
           super::content: handle,
           super::signed_by: signing_key.verifying_key(),
           super::signature_r: signature,
           super::signature_s: signature,
        };
    }

    if let Some(h) = msg {
        commit += entity! { &commit_entity @
           super::message: h,
        };
    }

    if let Some(handle) = metadata {
        commit += entity! { &commit_entity @
           super::metadata: handle,
        };
    }

    for parent in parents {
        commit += entity! { &commit_entity @
           super::parent: parent,
        };
    }

    commit
}

/// Validates that the `metadata` blob genuinely signs the supplied commit
/// `content`.
///
/// Returns an error if the signature information is missing, malformed or does
/// not match the commit bytes.
pub fn verify(content: Blob<SimpleArchive>, metadata: TribleSet) -> Result<(), ValidationError> {
    let handle = content.get_handle();
    let (pubkey, r, s) = match find!(
    (pubkey: Value<_>, r, s),
    pattern!(&metadata, [
    {
        super::content: handle,
        super::signed_by: ?pubkey,
        super::signature_r: ?r,
        super::signature_s: ?s
    }]))
    .at_most_one()
    {
        Ok(Some(result)) => result,
        Ok(None) => return Err(ValidationError::MissingSignature),
        Err(_) => return Err(ValidationError::AmbiguousSignature),
    };

    let pubkey: VerifyingKey = pubkey.try_from_value()?;
    let signature = Signature::from_components(r, s);
    pubkey.verify(&content.bytes, &signature)?;
    Ok(())
}