Package: integv
integvintegv is a file integrity verifier based on the format of the file. It's
capable of checking the integrity of multiple types of files without any
additional information like Content-Length or checksum. The main goal of integv
is to detect file corruption (mostly shortened) during file download caused by
network glitch. But integv still can be used for many other purposes as well.InstallationpipinstallintegvWhy integvSometimes when you download some media files usingrequests, a network glitch
happens and your file downloaded is corrupted. If there's aContent-Lengthheader, you can compare it to the downloaded file size. But the worst thing is
most of the time, media files are served using HTTP chunked transfer encoding,
and there's noContent-Lengthheader. So you don't know if the download file
is good or not. And that's the time integv comes to help, just feed the
downloaded file to integv and it can verify the integrity of the file with zero
other information likeContent-Length. All integv needs are the type of the file.integv has many advantages.integv is light, integv is written in pure python with 0 dependencies. Which
makes integv portable and easy to integrate into your project.integv is fast, integv does not try to decode the file, it just checks all the
key points in the file, so integv is much faster than other solutions that try
to decode the file.Here's a comparison of verifying a 70 MB mp4 file using integv and FFmpeg.
integv only takes about 60 microseconds, FFmpeg takes about 10 seconds.python3 -m timeit "import integv;integv.FileIntegrityVerifier().verify('../test.mp4')"
5000 loops, best of 5: 61.4 usec per loop

python3 -m timeit "import subprocess;subprocess.run('ffmpeg -v error -i ../test.mp4 -f null -', shell=True)"
1 loop, best of 5: 11.2 sec per loopQuick Startimportintegv# load a test mp4 filefile_path="./test/sample/video/sample.mp4"withopen(file_path,"rb")asf:file=f.read()# verify using the file and file_type# file_type can be a simple filename extension like "mp4" or "jpg"# or you can provide a full MIME type like "video/mp4" or "image/jpeg"integv.verify(file,file_type="mp4")# True# a corrupted file (in this case, shortened by one byte) will not pass the verificationintegv.verify(file[:-1],file_type="mp4")# False# the file input for the verifier can be bytes or a binary file like objectintegv.verify(open(file_path,"rb"),file_type="mp4")# True# it can also be a string representing a file path# if the file path contains a proper filename extension, the file_type is not needed.integv.verify(file_path)# TrueSupported typesVideomp4:video/mp4mkv:video/x-matroskawebm:video/webmavi:video/vnd.aviflv*:video/x-flv* not f4v. Basically, f4v is just mp4 with a different name.
For f4v files, use mp4 integrity verifier.Imagejpeg:image/jpegpng:image/pnggif:image/gifwebpimage/webpAudiowav:audio/x-wavogg:audio/oggLimitation of integvThe integv verifier only checks the file by the format information embedded in
file like file size in header, chunk size in chunk header, end of file markers,
etc. It does not try to decode the file which makes integv fast and simple.
But that also means the possibility of false negative (corrupted files can't be
detected). The baseline of all integv file integrity verifiers must be extremely
sensitive to shortened files, which is very common in file downloaded from the
network. Some types of files like png contain checksum inside, which is less
error-prone. By all means, do not use integv for any kind of security
verification. As a bad file which passes the verification can be simply forged.Effectiveness of integv on different types of corruptionTypes of corruption:SmallDeletion at theEnd of the file. (SDE)A few bytes of data were deleted at the end of the file. The length of the file
is reduced.Original file:  ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ
Corrupted file: ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYLargeDeletion at theEnd of the file. (LDE)A large chunk of data was deleted at the end of the file. The length of the
file is reduced.Original file:  ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ
Corrupted file: ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOSmallSubstitution at theEnd of the file. (SSE)A few bytes of data were substituted at the end of file. The length of the file
remains the same.Original file:  ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ
Corrupted file: ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYALargeSubstitution at theEnd of the file. (LSE)A large chunk of data was substituted at the end of file. The length of the
file remains the same.Original file:  ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ
Corrupted file: ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNAAAAAAAAAAAASmallDeletion at aRandom position of the file. (SDR)A few bytes of data were deleted at a random position of the file. The length of
the file is reduced.Original file:  ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ
Corrupted file: ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLNOPQRSTUVWXYZ
                                                      ^LargeDeletion at aRandom position of the file. (LDR)A large chunk of data was deleted at a random position of the file. The length
of the file is reduced.Original file:  ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ
Corrupted file: ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLYZ
                                                      ^SmallSubstitution at aRandom position of the file. (SSR)A few bytes of data were substituted at a random position of the file. The length
of the file remains the same.Original file:  ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ
Corrupted file: ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLANOPQRSTUVWXYZ
                                                      ^LargeSubstitution at aRandom position of the file. (LSR)A large chunk of data wass substituted at a random position of the file. The
length of the file remains the same.Original file:  ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ
Corrupted file: ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLAAAAAAAAAAWXYZ
                                                      ^Effectiveness TableFrom my personal experience, the most common types of corruption happen during
file downloading usingrequestsor similar things areSDEandLDE.SDELDESSELSESDRLDRSSRLSRmp4:smiley::smiley::frowning::smiley::smiley::smiley::frowning::smiley:mkv:smiley::smiley::frowning::smiley::smiley::smiley::frowning::smiley:webm:smiley::smiley::frowning::smiley::smiley::smiley::frowning::smiley:avi:smiley::smiley::frowning::frowning::smiley::smiley::frowning::frowning:flv:smiley::smiley::smiley::smiley::smiley::smiley::frowning::smiley:jpeg:smiley::smiley::smiley::smiley::frowning::frowning::frowning::frowning:png:smiley::smiley::smiley::smiley::smiley::smiley::smiley::smiley:gif:smiley::smiley::smiley::smiley::frowning::frowning::frowning::frowning:webp:smiley::smiley::frowning::frowning::smiley::smiley::frowning::frowning:wav:smiley::smiley::frowning::frowning::smiley::smiley::frowning::frowning:ogg:smiley::smiley::frowning::smiley::smiley::smiley::frowning::smiley:ogg(slow):smiley::smiley::smiley::smiley::smiley::smiley::smiley::smiley:Advanced UsageUsing a FileIntegrityVerifier objectYou can use a FileIntegrityVerifier object to verify your file just likeintegv.verify.fromintegvimportFileIntegrityVerifierverifier=FileIntegrityVerifier()verifier.verify("./test/sample/video/sample.mp4")# TrueSpecialized File Integrity VerifierThere are some specialized file integrity verifier for different types of files.
You can find them inintegv.video,integv.imageandintegv.audio. They are
used exactly like theFileIntegrityVerifierexceptfile_typeare not needed.fromintegv.videoimportMP4IntegrityVerifierverifier=MP4IntegrityVerifier()verifier.verify("./test/sample/video/sample.mp4")# TrueOptionalslowargument in verifier initializationA boolean argumentslowcan be provided in verifier initialization. It will
enable some sophisticated verification to eliminate false negatives. And that
will consume more time. The default value ofslowisFalse. For now, only
one verifier,OGGIntegrityVerifierhas aslowmethod of verification.fromintegvimportFileIntegrityVerifierverifier=FileIntegrityVerifier()slow_verifier=FileIntegrityVerifier(slow=True)file_path="./test/sample/audio/sample.ogg"verifier.verify(file_path)# Trueslow_verifier.verify(file_path)# also True, but slower