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.NET Forum / Languages / Managed C++ / June 2005Hash File Stream ?
Hello, I'm writing a security related application in .NET 1.1 and I wonder how I compute hashes from very large files (up to 1 GB). Does anybody know a good pattern of how to create a stream from a binary file and compute the hash of it? I appriciate your comments. Thanks in advance, Sebastain Dau. > Hello, > [quoted text clipped - 7 lines] > I appriciate your comments. > Thanks in advance, Sebastain Dau. Thread is closed... I got it. SHA256Managed* hash = new SHA256Managed (); String* sHashVal = UTF8Encoding->GetString ( hash->ComputeHash ( File::OpenRead ( "c:\test.txt" ) )); Hi Sebastian! >>I'm writing a security related application in .NET 1.1 >>and I wonder how I compute hashes from very large files (up to 1 GB). [quoted text clipped - 5 lines] > String* sHashVal = UTF8Encoding->GetString ( hash->ComputeHash ( > File::OpenRead ( "c:\test.txt" ) )); I dodnßt know if this is a good idea for large files ( > 1GB)... For this you need to read small pieces of the file and incremently create the hash...  SignatureGreetings Jochen My blog about Win32 and .NET http://blog.kalmbachnet.de/ >> SHA256Managed* hash = new SHA256Managed (); >> String* sHashVal = UTF8Encoding->GetString ( hash->ComputeHash ( [quoted text clipped - 3 lines] > For this you need to read small pieces of the file and incremently create > the hash... Right, that's exactly what it's doing... ComputeHash takes a stream object and internally hashes block by block File::OpenRead returns such a Stream inherited object. Greetings, Sebastian Hi Sebastian! >>>SHA256Managed* hash = new SHA256Managed (); >>>String* sHashVal = UTF8Encoding->GetString ( hash->ComputeHash ( [quoted text clipped - 5 lines] > > Right, that's exactly what it's doing... Upps... yes, you are right... sorry for the confusion... SignatureGreetings Jochen My blog about Win32 and .NET http://blog.kalmbachnet.de/ Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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