WinXP problem with large files was: Re: Decrypt problem with large file
snoken at tunedal.nu
Wed Nov 28 10:06:43 CET 2007
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.
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