Fix desktop updater latest.json generation for releases (#6540)

.github/scripts/verify-updater-signatures.py

@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+"""Verify Tauri updater .sig files against plugins.updater.pubkey in tauri.conf.json.
+
+Usage: verify-updater-signatures.py <dir-to-scan> [tauri.conf.json]
+"""
+
+import binascii
+import sys
+import json
+import base64
+import hashlib
+from pathlib import Path
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PublicKey
+from cryptography.exceptions import InvalidSignature
+
+ART_ROOT = Path(sys.argv[1])
+CONF = Path(
+    sys.argv[2] if len(sys.argv) > 2 else "frontend/editor/src-tauri/tauri.conf.json"
+)
+
+
+def load_pubkey():
+    # tauri pubkey = base64 of a minisign .pub file; last line is base64 of
+    # [2 algo][8 key-id][32 ed25519 public key].
+    raw = json.loads(CONF.read_text())["plugins"]["updater"]["pubkey"]
+    blob = base64.b64decode(base64.b64decode(raw).decode().splitlines()[-1])
+    return blob[2:10], Ed25519PublicKey.from_public_bytes(blob[10:])
+
+
+def hash_file(path: Path) -> bytes:
+    h = hashlib.blake2b(digest_size=64)
+    with path.open("rb") as f:
+        for chunk in iter(lambda: f.read(1 << 16), b""):
+            h.update(chunk)
+    return h.digest()
+
+
+def verify(artifact: Path, sig_file: Path, keyid_pub, pub) -> str:
+    # tauri .sig = base64 of a minisign signature file (4 lines).
+    try:
+        lines = base64.b64decode(sig_file.read_text()).decode().splitlines()
+        sig_blob = base64.b64decode(lines[1])
+    except (binascii.Error, IndexError, UnicodeDecodeError) as e:
+        return f"FAIL malformed sig ({type(e).__name__})"
+    algo, keyid, sig = sig_blob[:2], sig_blob[2:10], sig_blob[10:74]
+    if keyid != keyid_pub:
+        return f"FAIL key-id mismatch (sig {keyid.hex()} vs pub {keyid_pub.hex()})"
+    # 'ED' = prehashed (BLAKE2b-512), 'Ed' = legacy (raw message).
+    msg = hash_file(artifact) if algo == b"ED" else artifact.read_bytes()
+    try:
+        pub.verify(sig, msg)
+    except InvalidSignature:
+        return f"FAIL signature invalid (algo={algo.decode()})"
+    # Global signature covers sig + trusted_comment.
+    gc = "global-sig FAIL"
+    try:
+        tc = lines[2].split("trusted comment: ", 1)[1]
+        pub.verify(base64.b64decode(lines[3]), sig + tc.encode())
+        gc = "global-sig OK"
+    except (InvalidSignature, IndexError, binascii.Error):
+        pass
+    return f"VALID (algo={algo.decode()}, keyid={keyid.hex()}, {gc})"
+
+
+keyid_pub, pub = load_pubkey()
+print(f"updater pubkey keyid={keyid_pub.hex()}\n")
+sigs = sorted(ART_ROOT.rglob("*.sig"))
+if not sigs:
+    print(f"WARN: no .sig files under {ART_ROOT} - nothing to verify")
+    sys.exit(0)
+bad = 0
+for sig_file in sigs:
+    artifact = sig_file.with_suffix("")
+    if not artifact.exists():
+        print(f"  ? {sig_file.name}: artifact missing")
+        bad += 1
+        continue
+    res = verify(artifact, sig_file, keyid_pub, pub)
+    print(f"  {artifact.name}: {res}")
+    if not res.startswith("VALID") or "global-sig FAIL" in res:
+        bad += 1
+print(f"\n{'ALL SIGNATURES VALID' if bad == 0 else f'{bad} SIGNATURE(S) FAILED'}")
+sys.exit(1 if bad else 0)