摘要： P2P下载中文件完整性校验会影响下载性能，针对该问题，提出一种校验延迟的隐藏算法。利用文件完整性校验中使用的哈希算法的流式特性和TCP异步接收缓冲区的特点，将大文件块的哈希计算分成多次对较小的子数据块的计算，收到一个子数据块后，就开始计算哈希。由于计算每一个子数据块的哈希的时间开销很小，保证了计算延迟可以被TCP异步接收缓冲区所隐藏，使哈希计算与数据接收几乎可以并行进行，消除其对P2P文件下载性能的影响，提高了下载效率。

关键词: P2P下载, 文件校验, 延迟隐藏, SHA1算法, MD4算法

Abstract: A latency hiding algorithm, called HASH-Latency Hiding(HASH-LH), is promoted. By leveraging the streaming process characteristics of the Hash algorithms used for P2P file integrity verification and the asynchronous receiving buffer of TCP, it is reasonable for HASH-LH to divide a big file block into multiple smaller sub-blocks, which makes the latency much shorter for calculating Hash values on each sub-block. Furthermore, the Hash calculation starts just after the first sub-block is received. As the latency of each sub-block Hash calculation becomes as short as it can be hidden by the asynchronous receiving buffer of TCP, it makes calculation and receiving processed nearly at the same time. As a result, all the latency from file verification is hidden and performance boosts up.

Key words: P2P downloading, file verification, latency hiding, SHA1 algorithm, MD4 algorithm

中图分类号: 

• TP393