Hi I need to generate a SHA over a 5 Gig file
Do you know of a non string based Delphi library that can do this ?
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.
If you want to know how to read a large file buffered, see my answer about a file copy using custom buffering .
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;
I would recommend Wolfgang Ehrhardt's CRC/Hash.
http://home.netsurf.de/wolfgang.ehrhardt/
It's fast and "can be compiled with most current Pascal (TP 5/5.5/6, BP 7, VP 2.1, FPC 1.0/2.0/2.2) and Delphi versions (tested with V1 up to V7/9/10)".
I've used it with D11/D12 too.
如果我没记错的话,Indy会提供几种基于流的哈希方法。
@Davy Landman, thank you, your answer really helped me out. This is the code I ended up using:
function HashFileSHA256(const fileName: String): String;
var
sha256: TDCP_sha256;
buffer: array[0..1024*1024] of byte;
i, bytesRead: Integer;
streamIn: TFileStream;
hashBuf: array[0..31] of byte;
begin
// Initialization
Result := '';
streamIn := TFileStream.Create(fileName, fmOpenRead);
sha256 := TDCP_sha256.Create(nil);
for i:=0 to Sizeof(buffer) do
buffer[i] := 0;
for i:=0 to Sizeof(hashBuf) do
hashBuf[i] := 0;
bytesRead := -1;
// Compute
try
sha256.Init;
while bytesRead <> 0 do
begin
bytesRead := streamIn.Read(buffer[0], Sizeof(buffer));
sha256.Update(buffer[0], bytesRead);
end;
sha256.Final(hashBuf);
for I := 0 to 31 do
Result := Result + IntToHex(hashBuf[i], 2);
finally
streamIn.Free;
sha256.Free;
end;
Result := LowerCase(Result);
end;
PS: I am a total beginner with Pascal, so this code most likely sucks. But I tested it on the MSYS2 installer and was able to verify the hash, so that's nice.
There is a Delphi interface for OpenSSL, isn't there?
That should provide you with better performances.
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