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IDProjectCategoryView StatusLast Update
0031934Lazarus CCROtherpublic2020-03-07 15:24
ReporterScott Assigned To 
Status newResolutionopen 
Platformx64OSWindows Vista Home Premium 
Summary0031934: Component DCPHashes, which are part of DCPCrypt do not calculate Hashes correctly for files greatre than 4 GB
DescriptionWhen calculating the MD5, SHA1, SHA256 hashes for a file that is greater than 4 GB, the resulting hash is incorrect.
Steps To ReproduceTo give you a test file, go here:

Download the Windows 8.1 64-bit ISO (Win8.1_English_x64.iso)

Calculate one of these sums: MD5, SHA1, SHA256

The generated sums will be incorrect.

The incorrect hash sums that DCPHashes calculates for this file are as follows:

  FILE: Win8.1_English_x64.iso
   MD5: 1e356350e3719878493eb7270cf19251
  SHA1: 9954c50d6452095a2bb8fb3f1e2de75ed19a606d
SHA256: a056230d2f74a9a912a0e0d1e68259fda40ef51969cb4eee8c21160f60373ef4

The hash time is also very short, a matter of a few seconds, compared to a file that is just under 4 GB, which takes several minutes to compute.

The correct hash sums for the same file:

  FILE: Win8.1_English_x64.iso
   MD5: e0d4594e56c0545d379340e0db9519a5
  SHA1: a8b5df0b0816280ae18017bc4b119c77b6c6eb79
SHA256: d8333cf427eb3318ff6ab755eb1dd9d433f0e2ae43745312c1cd23e83ca1ce51
TagsNo tags attached.
Attached Files


has duplicate 0033853 resolvedBart Broersma DCPhashes: incorrect hash for files > 4GB 



2017-05-29 05:05

reporter   ~0100728

The same result also occurs when tested on Windows XP Service Pack 3 (x86).

Bart Broersma

2020-01-15 16:15

developer   ~0120465

You might ask Graeme Geldenhuys, he seems to be current maintainer (according to

Bart Broersma

2020-03-07 15:24

developer   ~0121432

I emailed Graeme.

Issue History

Date Modified Username Field Change
2017-05-29 05:04 Scott New Issue
2017-05-29 05:05 Scott Note Added: 0100728
2017-05-29 21:48 Bart Broersma Project Lazarus => Lazarus CCR
2018-07-28 18:05 Bart Broersma Relationship added has duplicate 0033853
2020-01-15 16:15 Bart Broersma Note Added: 0120465
2020-03-07 15:24 Bart Broersma Note Added: 0121432