WinXP problem with large files was: Re: Decrypt problem with large file

Snoken snoken at
Wed Nov 28 10:06:43 CET 2007

Hi again,
I found the old thread: Trouble decrypting AES256 symmetric encrypted file:

You  (Ryan) wrote:
This is surpisingly *not* a Windows issue. We have 200+ GB database
files on many of our database servers. All using NTFS.

I think the issue is that GnuPG is using a 32-bit DWORD file pointer
and the older file functions. Werner mentioned using GetFIleSize, but
the platform SDK indicates that you need to use GetFileSizeEx to
enable files greater than 2^32 bytes:

Werner, do you use GetFileSize or GetFileSizeEx? There are also
WriteFileEx and any number of other -Ex file-related functions to
handle files larger than 4 GB.



At 00:59 2007-11-28, you wrote:
 >> Snoken wrote:
 >> > is the old problem with files greater than 4 GB solved? How large
 >> > files can gpg handle on WindowsXP? On other systems?
 >My recollection is that the file size issue was fixed years ago, as it
 >was a limitation in the MinGW layer or something that was remedied. I
 >never followed up much, though, becuase GnuPG's encryption was very
 >slow compared with alternatives (7-zip). When I used GnuPG, encryption
 >was CPU-bound, even with compression turned off. When I use 7-zip,
 >encryption of our 500 GB backup files is disk-bound.
 >I also recall that Werner stated the AES code in GnuPG wouldn't be
 >optimized for a number of reasons, becasue of security (timing
 >attacks), and also a desire to keep GnuPG architecture-agnostinc. The
 >faster AES code used by 7-zip pretty much assumes a 32-bit x86
 >processor is the target. It's C, not assembler, but the data alignment
 >in 7-zip's code is very architecture specific.
 >Gnupg-users mailing list
 >Gnupg-users at

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