P2P文件完整性校验延迟隐藏算法

Latency Hiding Algorithm for P2P File Integrity Verification

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。

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.