lou
210 lines
7.4 KiB
Python
210 lines
7.4 KiB
Python
"""
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元数据生成模块 (metadata)
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模块:客户端 / 元数据生成
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输入:文件信息 + 加密参数 + 卷清单
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输出:init json (file_name/file_size/chunk_count/total_sha256/enc/chunks)
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init json 是服务端建任务的唯一依据 (POST /init 请求体),字段缺一不可,
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组装后先自校验再输出。chunks 剥离本地 filename (服务端不关心客户端路径)。
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用法:
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cd /home/lou/文档/7z-encrypt
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.venv/bin/python metadata.py [文件] [--chunk-size MB] [--key-id 密钥ID]
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"""
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import argparse
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import hashlib
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import json
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import sys
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from pathlib import Path
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from typing import Any
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from tqdm import tqdm
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from crypto import CryptoEngine, KeyNotFoundError
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from splitter import split_stream
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SHA256_HEX_LEN = 64
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DEFAULT_CHUNK_MB = 10
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class MetadataError(ValueError):
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"""init json 字段缺失或非法"""
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def _require_str(obj: dict[str, Any], key: str) -> str:
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v = obj.get(key)
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if not isinstance(v, str) or not v:
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raise MetadataError(f"字段 '{key}' 缺失或非空字符串")
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return v
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def _require_pos_int(obj: dict[str, Any], key: str) -> int:
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v = obj.get(key)
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if not isinstance(v, int) or isinstance(v, bool) or v <= 0:
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raise MetadataError(f"字段 '{key}' 缺失或非正整数")
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return v
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def _require_sha256(obj: dict[str, Any], key: str) -> str:
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v = _require_str(obj, key)
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if len(v) != SHA256_HEX_LEN:
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raise MetadataError(f"字段 '{key}' 长度不是 {SHA256_HEX_LEN} (SHA-256 hex)")
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return v
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def build_init_json(
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file_name: str,
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file_size: int,
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total_sha256: str,
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enc: dict[str, str],
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chunks: list[dict[str, Any]],
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) -> dict[str, Any]:
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"""组装并校验 init json
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Args:
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file_name: 原始文件名
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file_size: 原始文件字节数
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total_sha256: 密文整体 SHA-256 (服务端合并后验证)
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enc: 加密参数 {alg, key_id, context} (来自 crypto.encrypt_stream)
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chunks: 卷清单 (来自 splitter, 含 filename; 组装时剥离)
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Returns:
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dict: init json {file_name, file_size, chunk_count, total_sha256, enc, chunks}
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Raises:
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MetadataError: 任一必填字段缺失/非法/卷序号不连续
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"""
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# enc 校验
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if not enc:
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raise MetadataError("字段 'enc' 缺失或为空")
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for k in ("alg", "key_id", "context"):
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_require_str(enc, k)
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# chunks 校验 (序号必须 1..N 连续)
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if not chunks:
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raise MetadataError("字段 'chunks' 缺失或为空")
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clean_chunks: list[dict[str, Any]] = []
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for i, ch in enumerate(chunks, start=1):
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if ch.get("index") != i:
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raise MetadataError(
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f"chunks[{i}] 序号不连续 (期望 {i}, 实际 {ch.get('index')})"
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)
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clean_chunks.append({
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"index": i,
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"size": _require_pos_int(ch, "size"),
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"sha256": _require_sha256(ch, "sha256"),
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})
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# 整体校验
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if not file_name:
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raise MetadataError("file_name 缺失或为空")
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if isinstance(file_size, bool) or file_size <= 0:
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raise MetadataError("file_size 缺失或非法")
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if len(total_sha256) != SHA256_HEX_LEN:
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raise MetadataError(f"total_sha256 长度不是 {SHA256_HEX_LEN} (SHA-256 hex)")
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return {
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"file_name": file_name,
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"file_size": file_size,
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"chunk_count": len(clean_chunks),
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"total_sha256": total_sha256,
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"enc": enc,
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"chunks": clean_chunks,
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}
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def sha256_of(path: str | Path) -> str:
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"""流式计算文件 SHA-256 (不整块进内存)"""
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h = hashlib.sha256()
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with open(path, "rb") as f:
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while True:
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chunk = f.read(1 << 16)
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if not chunk:
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break
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h.update(chunk)
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return h.hexdigest()
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def main() -> int:
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ap = argparse.ArgumentParser(description="元数据生成: 加密 -> 分卷 -> 组装 init json")
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ap.add_argument("file", nargs="?", default="index.mp4", help="要处理的文件 (默认 index.mp4)")
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ap.add_argument("--chunk-size", type=int, default=DEFAULT_CHUNK_MB,
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help=f"每卷大小 MB (默认 {DEFAULT_CHUNK_MB})")
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ap.add_argument("--key-id", default="default_key", help="密钥ID (默认 default_key)")
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ap.add_argument("--file-name", help="覆盖 init json 的 file_name (压缩场景用原名)")
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ap.add_argument("--compressed", action="store_true",
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help="标记 7z 压缩 (enc_params 加 compressed, 下载端自动解压)")
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ap.add_argument("--no-encrypt-name", action="store_true",
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help="不加密文件名 (默认加密成 enc: 前缀)")
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args = ap.parse_args()
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src_path = Path(args.file).resolve()
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if not src_path.exists():
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print(f"[错误] 文件不存在: {src_path}")
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return 1
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chunk_size = args.chunk_size * 1024 * 1024
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enc_path = src_path.with_name(src_path.name + ".enc")
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manifest_path = src_path.with_name(src_path.name + "_manifest.json")
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init_path = src_path.with_name(src_path.name + ".init.json")
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print("=== 元数据生成 (加密 -> 分卷 -> init json) ===")
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print(f"文件: {src_path.name} ({src_path.stat().st_size / 1048576:.1f} MB), 卷大小: {args.chunk_size} MB")
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# 1. 加密 -> 加密参数
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engine = CryptoEngine()
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try:
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engine.get_key(args.key_id)
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except KeyNotFoundError:
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engine.generate_key(args.key_id)
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print(f"[密钥库] 已生成新密钥 -> {engine.keyring_path}")
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with open(src_path, "rb") as src, open(enc_path, "wb") as dst:
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pbar = tqdm(total=src_path.stat().st_size, desc="[加密]", unit="B",
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unit_scale=True, leave=False)
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enc_params = engine.encrypt_stream(src, dst, args.key_id,
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progress=lambda n: pbar.update(n))
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pbar.close()
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print(f"[1/4] 加密完成 -> {enc_path.name} ({enc_path.stat().st_size / 1048576:.1f} MB)")
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# 2. 分卷 -> 卷清单
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with open(enc_path, "rb") as f:
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pbar = tqdm(total=enc_path.stat().st_size, desc="[分卷]", unit="B",
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unit_scale=True, leave=False)
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manifest = split_stream(f, chunk_size, str(enc_path),
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total_size=enc_path.stat().st_size,
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progress=lambda n: pbar.update(n))
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pbar.close()
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with open(manifest_path, "w", encoding="utf-8") as f:
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json.dump(manifest, f, indent=2, ensure_ascii=False)
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print(f"[2/4] 分卷完成: {len(manifest)} 卷, 清单 -> {manifest_path.name}")
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# 3. 密文整体 SHA-256
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total_sha256 = sha256_of(enc_path)
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print(f"[3/4] 密文 SHA-256: {total_sha256}")
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# 4. 组装 init json
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if args.compressed:
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enc_params["compressed"] = True # 下载端据此 7z 解压
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file_name = args.file_name or src_path.name
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if not args.no_encrypt_name:
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# 元数据零知识: 文件名加密成 'enc:' 前缀 (服务端只存密文, 客户端解密还原)
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file_name = engine.encrypt_name(file_name)
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init_json = build_init_json(
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file_name=file_name,
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file_size=src_path.stat().st_size,
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total_sha256=total_sha256,
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enc=enc_params,
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chunks=manifest,
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)
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with open(init_path, "w", encoding="utf-8") as f:
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json.dump(init_json, f, indent=2, ensure_ascii=False)
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print(f"[4/4] init json -> {init_path.name}")
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print("\n=== init json ===")
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print(json.dumps(init_json, indent=2, ensure_ascii=False))
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return 0
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if __name__ == "__main__":
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sys.exit(main())
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