boundary_compiler/
digest.rs

1//! blake3 ContentDigest over JCS bytes.
2//!
3//! RFC 8785 does not define a digest algorithm; this module computes a blake3
4//! Content-Digest over the canonical JSON bytes, following the IETF Content-Digest
5//! spec (RFC 9562, draft-ietf-httpbis-digest-headers).
6
7use crate::error::JcsError;
8use blake3::Hash;
9
10/// A blake3 content digest of JCS bytes, in hex.
11#[derive(Debug, Clone, PartialEq, Eq)]
12pub struct ContentDigest(pub Hash);
13
14impl ContentDigest {
15    /// Computes the blake3 content digest over the JCS bytes of a JSON value.
16    pub fn compute(value: &serde_json::Value) -> Result<Self, JcsError> {
17        use crate::canonicalizer::Canonicalizer;
18        let canonical_bytes = Canonicalizer::new().canonicalize_bytes(value)?;
19        Ok(Self(blake3::hash(&canonical_bytes)))
20    }
21
22    /// Returns the hex-encoded digest.
23    pub fn hex(&self) -> String {
24        self.0.to_hex().to_string()
25    }
26
27    /// Returns the raw digest bytes.
28    pub fn as_bytes(&self) -> [u8; 32] {
29        *self.0.as_bytes()
30    }
31}
32
33impl std::fmt::Display for ContentDigest {
34    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
35        write!(f, "{}", self.hex())
36    }
37}
38
39impl std::fmt::LowerHex for ContentDigest {
40    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
41        write!(f, "{}", self.hex())
42    }
43}
44
45#[cfg(test)]
46mod tests {
47    use super::*;
48    use serde_json::json;
49
50    #[test]
51    fn test_digest_same_input_same_output() {
52        let val = json!({"b": 1, "a": 2});
53        let d1 = ContentDigest::compute(&val).unwrap();
54        let d2 = ContentDigest::compute(&val).unwrap();
55        assert_eq!(d1, d2);
56        assert_eq!(d1.hex(), d2.hex());
57    }
58
59    #[test]
60    fn test_digest_different_inputs_different_output() {
61        let val1 = json!({"a": 1});
62        let val2 = json!({"a": 2});
63        let d1 = ContentDigest::compute(&val1).unwrap();
64        let d2 = ContentDigest::compute(&val2).unwrap();
65        assert_ne!(d1, d2);
66    }
67
68    #[test]
69    fn test_digest_is_deterministic() {
70        let val = json!({"z": {"b": [1, 2], "a": null}, "a": true});
71        let d1 = ContentDigest::compute(&val).unwrap();
72        // Run multiple times
73        for _ in 0..10 {
74            let d2 = ContentDigest::compute(&val).unwrap();
75            assert_eq!(d1, d2);
76        }
77    }
78
79    #[test]
80    fn test_digest_display() {
81        let val = json!({"x": 1});
82        let d = ContentDigest::compute(&val).unwrap();
83        let display = format!("{}", d);
84        let hex = format!("{:x}", d);
85        assert_eq!(display, hex);
86    }
87}
boundary_compiler/digest.rs

boundary_compiler/
digest.rs
