本地计算文件的保管箱哈希 [英] Locally calculate dropbox hash of files

问题描述

Dropbox rest api，在metatada函数中有一个名为哈希的参数 https：/ /www.dropbox.com/developers/reference/api#metadata

Dropbox rest api, in function metatada has a parameter named "hash" https://www.dropbox.com/developers/reference/api#metadata

我可以在不调用任何远程api rest函数的情况下在本地计算此哈希值吗？

Can I calculate this hash locally without call any remote api rest function?

我需要知道此值以减少上传带宽。

I need know this value to reduce upload bandwidth.

推荐答案

https://www.dropbox.com/developers/reference/content-hash 解释了如何Dropbox计算其文件哈希。以下是Python的实现：

https://www.dropbox.com/developers/reference/content-hash explains how Dropbox computes their file hashes. A Python implementation of this is below:

import hashlib
import math
import os

DROPBOX_HASH_CHUNK_SIZE = 4*1024*1024

def compute_dropbox_hash(filename):
    file_size = os.stat(filename).st_size
    with open(filename, 'rb') as f:
        block_hashes = b''
        while True:
            chunk = f.read(DROPBOX_HASH_CHUNK_SIZE)
            if not chunk:
                break
            block_hashes += hashlib.sha256(chunk).digest()
        return hashlib.sha256(block_hashes).hexdigest()

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