freeware rar utility
Free rar software
   DOWNLOAD PEAZIP FREE RAR AND ZIP UTILITY
ONLINE SUPPORT SOFTWARE'S FAQ
LEARN MORE
rar free
free rar software free rar utility
portable rar rar freeware free rar
free rar tool

free checksum program

PeaZip is a free cross-platform file archiver and file hashing utility that provides an unified portable GUI for many Open Source technologies like 7-Zip, FreeArc, PAQ, UPX...
Create 7Z, ARC, BZ2, GZ, *PAQ, PEA, QUAD/BALZ, TAR, UPX, WIM, XZ, ZIP files
Open and extract over 180 archive types: ACE, ARJ, CAB, DMG, ISO, LHA, RAR, UDF, ZIPX files and more...
Features of PeaZip includes extract, create and convert multiple archives at once, create self-extracting archives, split/join files, strong encryption with two factor authentication, encrypted password manager, secure deletion, find duplicate files, calculate hashes, export job definition as script.

file hasing utility

free rar
FAQ / FILE MANAGER > CALCULATE CHECKSUM AND HASH
open source rar

Verify file integrity (hash, checksum)



COMPUTE CRC, MD5, SHA, RIPEMD HASH TO DETECT DATA CORRUPTION

detect file corruption



PeaZip provides primitives to compute multiple hash and checksum algorithms, and this feature can be used either to find duplicate files (which have identical checksum/hash value), and to detect corrupted files which have different checksum / hash value from a known one.
Data corruption may arise by simple technical issues - transmission faults, degradation of memory support - which can usually be detected with ease by quick and computationally light functions (often integrated at various levels of transmission protocols and memory technologies), or may arise from forgery, purposely crafted modifications of data created by a malicious attacker to exploit weakness of simpler error detection mechanisms - which requires calculation of more powerful verification functions like cryptographically strong hash algorithms.


Compute error detection algorithms


Check files entry in "File tools" submenu (context menu) allows to verify multiple hash and checksum algorithms on multiple files at once, e.g. to compare a group of file to identify redundant ones, or to check files for corruption when an original checksum or hash value is known (or when it can be calculated for reference from a known safe copy of the data).
Selected algorithms are performed in a single passage so reading the data from disk (usually the main performance bottleneck) occurs only one time, speeding up the disk-bound part of the process.

The algorithms to be performed can be selected in Options > Settings, in File Tools tab; calculated output value of hashes and checksums can be seen as exadecimal (HEX, either LSB or MSB) or encoded as Base64.

15 checksum and hash algorithms are currently supported:
  • checksum functions Adler32, CRC16, CRC24, CRC32, CRC64

  • general-purpose hash functions as eDonkey/eMule, MD4, MD5

  • cryptographically strong hash:

    • Ripemd160

    • SHA-1

    • SHA-2 family (SHA256, SHA512)

    • SHA-3 family (SHA-3 256, SHA-3 512)

    • AES-based Whirlpool512


error detection algorithm

Hint: chose faster checksums like CRC32 to perform a quick comparison (e.g. to detect duplicate files of test for casual corruption data errors), but it is recommended to employ a cryptographically secure hash function (like sha-2-family SHA256, SHA512, SHA-3 algorithms, or the AES-based Whirlpool512) to detect malicious corruption / forgery attacks that might be calculated in order to pass undetected to one (or some) of the non-secure algorithms exploiting collision - algorithm maps different input to same ouput digest.

calculate file hash


Employing multiple functions at once, and especially relying on cryptographically strong hash functions as Ripemd160, SHA-2, SHA-3 or Whirlpool, can defeat attempt of forging identical-looking files, as it is computationally feasible to find a collision (different input files mapped to same output digest) for simpler checksum and hash functions, while finding digest value collisions is currently not computationally feasible for more robust cryptographic hash functions.

This way, even a purposely crafted modification of a file would not pass unnoticed to most sophisticated error / forgery detection algorithms, making possible to identify not only plain data corruption (e.g. communication or device fault) but also to avoid certain classes of attacks relying on replacing original content with forged data.


Byte-to-byte file comparison


Compare files entry in "File tools" submenu performs byte to byte comparison between two files, a slower process in which all single bytes of one file are verified and matched with the same offset byte of the other file.
Unlike checksum / hash comparison, this method it is not subject to collisions under any circumstance, and can effectively tell what the different bytes are, providing not only a way to verify if two files are identical or different, but also to find in details what changes were made between the two versions.


Test archive for errors


Most archive formats can be tested for errors using PeaZip routines (Test button), detecting if data is correctly readable and matches file format specification's standards, either testing archive table of content and single archive items.
Some archive types (7z, rar, tar, zipx...) improves error detection storing pre-computed checksum values (usually CRC32) of archived data.
Data errors can be due to random corruption (faulty support, troubles during download), out of standard archiving processes (bug, obsolete specifications), or in worst case purposeful alteration of original content. In some cases corruption or alteration of data can lead to an unreadable archive as result.
Testing archives for errors is an useful good practice sufficient for low risk scenarios, but if there is a reasonable suspicion of the data being purposely manipulated it is preferable to test the file with a cryptographically strong hash function (SHA family, Ripemd, Whirlpool) against a known value, using aforementioned "Check files" tool.
PEA file format provides a wide array of strong hash functions and authenticated encryption options, saving inside the archive the calculated digest values.
In this way the data integrity can be thoroughly tested during extraction, reducing needs of relying on external hashing tools, for verification both of integrity and autenticity of the content.

Read more about error detection and related topics: definitions of data integrityverify file content, checksumvalidate data integrity, hashfind hash value, cryptographically secure hash functioncryptographic hash algorithms, and data deduplicationidentify duplicates on Wikipedia, sha-2-familyfips certified hash standard.


RELATED & SIMILAR PAGES
DETECT DUPLICATE FILES
PROTECT INTEGRITY OF PRIVATE FILES
Tag Cloud
7z file type ace files cab files checksum utility convert archives compare files CRC detect data corruption encrypt files extract rar file extract zip files file management find duplicate files free zip utility hash files MD5 open iso image open rar password protection rar files extraction rar software download secure delete SHA split files tar files unrar unzip files verify file integrity zip file software zipx files utility





download rar software
DOWNLOADS
free rar archiver
All PeaZip downloads
PeaZip for Windows 32 bit
PeaZip for Windows 64 bit
PeaZip Portable
PeaZip Linux/BSD
online rar program support
SUPPORT
how do i zip unzip files
Online help
Frequently Asked Questions
More information





open rar files
DONATE
rar files
Support PeaZip project, or donate to FAO, UNICEF and UNESCO from donation page

© PeaZip srl: TOS, Privacy
OSDN software repository
free rar downloads
SourceForge software repository
free rar
Releases Feed zipx files
PeaZip Wiki rar files
Developer email download rar software
Search knowledge-base
rar archiver