#!/usr/bin/env python3 """Sign/verify an offline release manifest. Requires OpenSSL 3 with Ed25519. The signing key belongs outside the repository and must never ship to customers. A verifier must obtain the public-key fingerprint from a trusted separate channel. This verifies delivered files, not the identity of a running patched process. """ import argparse import hashlib import json import os from pathlib import Path import subprocess import sys import tempfile PRODUCT = "BMX STAGE AUDIO" MAX_MANIFEST = 4 * 1024 * 1024 def openssl(*args): result = subprocess.run([os.environ.get("BMX_OPENSSL", "openssl"), *map(str, args)], stdout=subprocess.PIPE, stderr=subprocess.PIPE) if result.returncode: raise ValueError("OpenSSL 操作失败：请检查版本、密钥格式或数字签名。") return result.stdout def digest(path): h = hashlib.sha256() with path.open("rb") as f: for block in iter(lambda: f.read(1024 * 1024), b""): h.update(block) return h.hexdigest() def fingerprint(public): return hashlib.sha256(openssl("pkey", "-pubin", "-in", public, "-outform", "DER")).hexdigest() def release_file(root, name): p = Path(name) if p.is_absolute() or "\\" in name or ".." in p.parts or not p.parts or p.as_posix() != name: raise ValueError("发行清单包含无效路径。") candidate = root / p if candidate.is_symlink() or not candidate.is_file() or not candidate.resolve().is_relative_to(root.resolve()): raise ValueError("发行文件缺失或路径超出发行目录。") return candidate def keygen(private, public): if private.exists() or public.exists(): raise ValueError("密钥文件已存在，拒绝覆盖。") private.parent.mkdir(mode=0o700, parents=True, exist_ok=True) public.parent.mkdir(parents=True, exist_ok=True) # Reserve the secret with owner-only permissions before OpenSSL writes it. fd = os.open(private, os.O_CREAT | os.O_EXCL | os.O_WRONLY, 0o600) os.close(fd) openssl("genpkey", "-algorithm", "ED25519", "-out", private) openssl("pkey", "-in", private, "-pubout", "-out", public) print("公钥 SHA-256 (DER):", fingerprint(public)) def sign(root, files, private, manifest): signature = Path(str(manifest) + ".sig") if manifest.exists() or signature.exists(): raise ValueError("签名输出已存在，拒绝覆盖。") if not 0 < len(files) <= 1000 or len(set(files)) != len(files): raise ValueError("发行文件列表为空、重复或过长。") entries = [] for name in sorted(files): f = release_file(root, name) if f.resolve() in (private.resolve(), manifest.resolve(), signature.resolve()): raise ValueError("禁止把密钥或清单本身打包进发行文件列表。") entries.append({"file": name, "bytes": f.stat().st_size, "sha256": digest(f)}) version = json.loads((Path(__file__).resolve().parent.parent / "package.json").read_text())["version"] data = {"schema": 1, "product": PRODUCT, "version": version, "algorithm": "Ed25519", "files": entries} manifest.write_bytes((json.dumps(data, ensure_ascii=False, indent=2) + "\n").encode()) openssl("pkeyutl", "-sign", "-rawin", "-inkey", private, "-in", manifest, "-out", signature) print("PASS: 发行清单已签名，文件数", len(entries)) def verify(root, public, trusted, manifest): if manifest.stat().st_size > MAX_MANIFEST: raise ValueError("发行清单过大。") # Freeze the bytes being checked; do not reopen a mutable original after verification. data = manifest.read_bytes() if len(data) > MAX_MANIFEST: raise ValueError("发行清单过大。") public_data = public.read_bytes() signature_data = Path(str(manifest) + ".sig").read_bytes() if len(signature_data) != 64 or len(public_data) > 4096: raise ValueError("公钥或签名长度无效。") with tempfile.TemporaryDirectory(prefix="bmx-verify-") as temp: frozen = Path(temp) / "manifest.json" frozen.write_bytes(data) frozen_public = Path(temp) / "public.pem" frozen_public.write_bytes(public_data) frozen_sig = Path(temp) / "signature.bin" frozen_sig.write_bytes(signature_data) if not trusted or fingerprint(frozen_public) != trusted.lower(): raise ValueError("公钥指纹与可信来源不一致。") openssl("pkeyutl", "-verify", "-pubin", "-inkey", frozen_public, "-rawin", "-in", frozen, "-sigfile", frozen_sig) obj = json.loads(data) if obj.get("schema") != 1 or obj.get("product") != PRODUCT or obj.get("algorithm") != "Ed25519": raise ValueError("不是受支持的 BMX 发行清单。") entries = obj.get("files") if not isinstance(entries, list) or not 0 < len(entries) <= 1000: raise ValueError("发行清单文件列表无效。") seen = set() for entry in entries: name = entry["file"] if name in seen: raise ValueError("发行清单文件重复。") seen.add(name) f = release_file(root, name) if f.stat().st_size != entry["bytes"] or digest(f) != entry["sha256"]: raise ValueError("发行文件被更改或下载不完整：" + name) print("PASS: 可信公钥、Ed25519 签名及全部发行文件校验通过；文件数", len(entries)) def main(): p = argparse.ArgumentParser(description=__doc__) sub = p.add_subparsers(dest="action", required=True) k = sub.add_parser("keygen") k.add_argument("--private-key", required=True, type=Path) k.add_argument("--public-key", required=True, type=Path) s = sub.add_parser("sign") s.add_argument("--private-key", required=True, type=Path) s.add_argument("--root", required=True, type=Path) s.add_argument("--manifest", required=True, type=Path) s.add_argument("files", nargs="+") v = sub.add_parser("verify") v.add_argument("--public-key", required=True, type=Path) v.add_argument("--trusted-key-sha256", required=True) v.add_argument("--root", required=True, type=Path) v.add_argument("--manifest", required=True, type=Path) a = p.parse_args() try: if a.action == "keygen": keygen(a.private_key, a.public_key) elif a.action == "sign": sign(a.root, a.files, a.private_key, a.manifest) else: verify(a.root, a.public_key, a.trusted_key_sha256, a.manifest) except (ValueError, OSError, KeyError, TypeError) as e: print("FAIL:", e, file=sys.stderr) return 1 return 0 if __name__ == "__main__": sys.exit(main())