Delphi：如何计算大文件的SHA哈希 [英] Delphi: How to calculate the SHA hash of a large file

问题描述

我需要在5 Gig文件上生成SHA。

Hi I need to generate a SHA over a 5 Gig file

您知道基于非字符串的Delphi库吗？

Do you know of a non string based Delphi library that can do this ?

推荐答案

您应使用 DCPcrypt v2 并读取缓冲的文件，并使用缓冲区为SHA哈希器提供数据，直到您读取完整的5GB文件为止。

You should use DCPcrypt v2 and read your file buffered and feed the SHA hasher with the buffer until you've read the complete 5GB file.

如果您想知道如何读取已缓冲的大文件，请参阅我的答案有关使用自定义缓冲的文件副本。

If you want to know how to read a large file buffered, see my answer about a file copy using custom buffering.

所以在概念上（没有真正的delphi代码！）：

so in concept (no real delphi code!):

function GetShaHash(const AFilename: String)
begin
  sha := TSHAHasher.Create;
  SetLength(Result, sha.Size);
  file := OpenFile(AFilename, GENERIC_READ);
  while not eof file do
  begin
     BytesRead := ReadFile(file, buffer[0], 0, 1024 * 1024);
     sha.Update(buffer[0], BytesRead);
  end;
  sha.Final(Result[0]); 
  CloseFile(file);
end;

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