From 8218fd584e4053848738a310258893e14c4ee10e Mon Sep 17 00:00:00 2001
From: salmonik <salmonik@tuta.io>
Date: Mon, 24 Aug 2026 15:27:06 +0200
Subject: TOFU host trust: SPKI fingerprint pinning, tests, forget-host

---
 tests/tofu.rs | 139 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 tests/tofu.rs

(limited to 'tests/tofu.rs')

diff --git a/tests/tofu.rs b/tests/tofu.rs
new file mode 100644
index 0000000..260e1b6
--- /dev/null
+++ b/tests/tofu.rs
@@ -0,0 +1,139 @@
+//! TOFU trust tests.
+//!
+//! These pin the not-yet-implemented TOFU behavior: every test here is
+//! expected to FAIL until the corresponding feature lands in `src/tofu.rs`
+//! and the client storage layer.
+
+use std::path::PathBuf;
+use std::process::Command;
+
+use zagan_bet::client_database;
+use zagan_bet::tofu::{decide, spki_fingerprint, TrustDecision};
+
+/// Generate a self-signed certificate under target/ and return its DER bytes.
+fn make_cert(tag: &str) -> Vec<u8> {
+    let dir = PathBuf::from(env!("CARGO_TARGET_TMPDIR")).join("tofu-certs");
+    std::fs::create_dir_all(&dir).unwrap();
+    let key = dir.join(format!("{tag}.key"));
+    let pem = dir.join(format!("{tag}.pem"));
+    if !pem.exists() {
+        let status = Command::new("openssl")
+            .args([
+                "req",
+                "-x509",
+                "-newkey",
+                "rsa:2048",
+                "-keyout",
+                key.to_str().unwrap(),
+                "-out",
+                pem.to_str().unwrap(),
+                "-days",
+                "365",
+                "-nodes",
+                "-subj",
+                "/CN=zagan-test",
+            ])
+            .status()
+            .expect("openssl must be available for tests");
+        assert!(status.success(), "openssl failed");
+    }
+    // Convert PEM to DER.
+    let status = Command::new("openssl")
+        .args([
+            "x509",
+            "-in",
+            pem.to_str().unwrap(),
+            "-outform",
+            "DER",
+            "-out",
+            dir.join(format!("{tag}.der")).to_str().unwrap(),
+        ])
+        .status()
+        .unwrap();
+    assert!(status.success());
+    std::fs::read(dir.join(format!("{tag}.der"))).unwrap()
+}
+
+/// Independent expected value computed with openssl, not with our code:
+/// SHA-256 over the SPKI DER of the certificate.
+fn openssl_spki_sha256(pem_path: &str) -> String {
+    let out = Command::new("sh")
+        .arg("-c")
+        .arg(format!(
+            "openssl x509 -in {pem} -pubkey -noout | \
+             openssl pkey -pubin -outform DER | sha256sum",
+            pem = pem_path
+        ))
+        .output()
+        .unwrap();
+    assert!(out.status.success());
+    let s = String::from_utf8(out.stdout).unwrap();
+    s.split_whitespace().next().unwrap().to_string()
+}
+
+#[test]
+fn fingerprint_is_sha256_of_spki() {
+    let der = make_cert("primary");
+    let dir = PathBuf::from(env!("CARGO_TARGET_TMPDIR")).join("tofu-certs");
+    let expected = openssl_spki_sha256(dir.join("primary.pem").to_str().unwrap());
+
+    let fp = spki_fingerprint(&der).expect("must parse the test certificate");
+    assert_eq!(fp, expected, "fingerprint must equal openssl's SPKI SHA-256");
+}
+
+#[test]
+fn fingerprint_rejects_garbage() {
+    assert!(spki_fingerprint(b"not a certificate").is_err());
+}
+
+#[test]
+fn first_contact_trusts_and_records() {
+    let observed = "ab12cd34";
+    assert_eq!(decide(None, observed), TrustDecision::TrustNew);
+}
+
+#[test]
+fn matching_key_is_trusted() {
+    assert_eq!(
+        decide(Some("ab12cd34"), "ab12cd34"),
+        TrustDecision::Trusted
+    );
+}
+
+#[test]
+fn changed_key_is_mismatch_with_details() {
+    let d = decide(Some("ab12cd34"), "ef56ab78");
+    match d {
+        TrustDecision::Mismatch { expected, actual } => {
+            assert_eq!(expected, "ab12cd34");
+            assert_eq!(actual, "ef56ab78");
+        }
+        other => panic!("expected Mismatch, got {:?}", other),
+    }
+}
+
+/// Fingerprint persistence roundtrip in the client database.
+#[test]
+fn fingerprint_roundtrip_in_client_db() {
+    let db_path = PathBuf::from(env!("CARGO_TARGET_TMPDIR"))
+        .join("tofu-roundtrip.db")
+        .to_string_lossy()
+        .into_owned();
+    let _ = std::fs::remove_file(&db_path);
+    let conn = rusqlite::Connection::open(&db_path).unwrap();
+    client_database::init_db(&conn);
+
+    // Host starts unknown.
+    assert_eq!(client_database::get_fingerprint(&conn, "host1"), None);
+
+    // Save, read back.
+    client_database::save_fingerprint(&conn, "host1", "deadbeef").unwrap();
+    assert_eq!(
+        client_database::get_fingerprint(&conn, "host1"),
+        Some("deadbeef".to_string())
+    );
+
+    // Forget clears it.
+    client_database::forget_host(&conn, "host1").unwrap();
+    assert_eq!(client_database::get_fingerprint(&conn, "host1"), None);
+}
-- 
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