Jacksum is a free and platform independent software for computing and verifying checksums, CRCs and message digests.
Jacksum supports 44 popular algorithms (Adler32, BSD sum, POSIX cksum, CRC-8, CRC-16, CRC-24, CRC-32 (FCS-32), CRC-64, ELF-32, eMule/eDonkey, FCS-16, GOST R 34.11-94, HAVAL (3/4/5 passes, 128/160/192/224/256 bits), MD2, MD4, MD5, MPEG-2's CRC-32, RIPEMD-128, RIPEMD-160, RIPEMD-256, RIPEMD-320, SHA-0, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, Tiger-128, Tiger-160, Tiger, Tiger2, Unix System V sum, sum8, sum16, sum24, sum32, Whirlpool-0, Whirlpool-1, Whirlpool and xor8).
Jacksum has opened it's source code and it is released under the terms of the GNU GPL. Jacksum is OSI Certified Open Source Software. OSI Certified is a certification mark of the Open Source Initiative.
Jacksum is platform independent, because it is written entirely in the Java programming language, the software runs on any platform having a Java Runtime Environment.
With Jacksum you can check if a filetransfer was successful. If you download software or huge files, like CD-images (so called iso files) from the internet, often there is a checksum or a hashcode provided. With Jacksum you can calculate such a checksum or hashcode from your local copy. If both checksequences are identical you know that the filetransfer was successful.
As Jacksum supports recursively file processing, you can compare two directory trees. Therefore you will be able to verify, if your copies or backups are identical with the original source, even if you don't have access to both trees at the same time (compare two DVDs with just one drive for example).
Jacksum can assist you if you want to perform an unidirectional sync of two directory trees, even if they are on two different computer without a connection in between.
As Jacksum reads each byte of a file, you can check if all files are still readable on your CD-ROM or DVD.
As Jacksum supports a platform independent and compatible file format, it helps you to verify data integrity of burned data on CD-ROMs or DVDs even after many years and even if you will have changed your Operating System.
Jacksum can help you to create incremental backups. If you are a developer, Jacksum can help you to create patches for your customers.
You can use Jacksum for intrusion detection, because Jacksum can check whether and what files have been changed or deleted on your system. Jacksum can not only check the content of each file you want, but also the file timestamps.
Use Jacksum for website content change detection, so get informed if something has changed on your favorite website (can be useful if the website has no announcement-mail-alias).
Here are some key features of "Jacksum":
ˇ This software is OSI Certified Open Source software
ˇ It is entirely free software (it runs on free platforms and therefore it is listed also at the Free Software Foundation directory)
ˇ It is free of charge, it costs nothing
ˇ It is free of registration (well, I'm happy if you write an e-mail to firstname.lastname@example.org for feedback)
ˇ It never expires
ˇ JRE version 1.3.1 or later
What's New in This Release:
ˇ added a customizable CRC algorithm, now you can calculate any CRC which can be described by the Rocksoft Model CRC Algorithm (8 to 64 bit width), see also sf# 1518023 Setting of an initial value for a CRC
ˇ support for combinable checksums, see also sf# 1210489 (multiple hashes at the same time), thanks to synonymous2 for this feature request support for using all algorithms at once (-a all) two new algorithms are supported: crc32_bzip2, HAS-160
ˇ support for Tiger Tree hashes (aka Merkle Hashes). Thanks to Carsten Krüger, Germany for the feature request and pointers to some resources
ˇ support for new encodings (bin, dec, oct)
ˇ support for the combination of both options -c and -w, Thanks to Dipl.-Inf. (FH) Ralf Kahrl, Germany for the implementation of this feature a small performance improvement for the whirlpool algorithms
ˇ replaced the crc24 with a faster one by using the customizable CRC algorithm (the old one had also a minor bug in the parameterless constructor)
ˇ bug fixed: -V summary does not always return reasonable values
ˇ bug fixed: update(byte, int, int) fails if offset is > 0 (sf # 1525183) This can cause problems if Jacksum is incorporated in different projects
ˇ The bouncycastle and gnu classes have been moved to jonelo.jacksum.adapt so that they won't clash with different downloaded versions of the classes. Actually this is to avoid potential problems if a project uses both bouncycastle and Jacksum for example. Thanks to Alberto Rodriguez, Spain for the feature request documentation updated (BeOS' data integrity programs, Tru64 and year of the invention for many algorithms)
ˇ tested with gij 4.0.2, JRE 1.3.1_18, 1.4.2_12, 5.0_07, 6.0-rc-b93