tiny.content.Identifier

1/// Carries the identity of content, and nothing else about it, so a caller2/// compares identifiers to decide whether two byte strings are the same. The3/// struct holds two fields: the algorithm and its 32-byte digest, so it names4/// no location, no provider, and no type.5pub const Identifier = struct {6    algorithm: Algorithm,7    digest: [digest_bytes]u8,89    /// Derives an identifier from the complete bytes by running the chosen hash10    /// over every byte and pairing the digest with the algorithm tag.11    pub fn fromBytes(algorithm: Algorithm, bytes: []const u8) Identifier {12        var digest: [digest_bytes]u8 = undefined;13        switch (algorithm) {14            .blake3 => std.crypto.hash.Blake3.hash(bytes, &digest, .{}),15            .sha256 => std.crypto.hash.sha2.Sha256.hash(bytes, &digest, .{}),16        }17        return .{ .algorithm = algorithm, .digest = digest };18    }1920    /// Reports whether two identifiers carry the same algorithm and the same21    /// digest, which is how a provider looks for an identifier among the ones22    /// it holds. The check compares the digests in constant time, so the answer23    /// leaks nothing about where they first differ.24    pub fn eql(left: Identifier, right: Identifier) bool {25        const algorithm_matches = left.algorithm == right.algorithm;26        const digest_matches = std.crypto.timing_safe.eql(27            [digest_bytes]u8,28            left.digest,29            right.digest,30        );31        return algorithm_matches and digest_matches;32    }3334    /// Checks bytes a provider staged or read by rehashing them with this35    /// identifier's algorithm and reporting whether the digests agree.36    pub fn matches(self: Identifier, bytes: []const u8) bool {37        return self.eql(fromBytes(self.algorithm, bytes));38    }39};

1pub const Identifier = model.Identifier;