Find algorithms to a hash value using Jacksum

 If you need to find the algorithm to a CRC, checksum or hash value you can use Jacksum.

For those who don't know: Jacksum is a free and cross platform data integrity software tool. For more information go to https://jacksum.net

Let's keep things simple and let's pretend that you know your algorithm returns a message digest of 16 bits, and the the message digest is d893 in hex, lowercase. Input was 050000 in hex, lowercase. You can call jacksum with the following options:

• Option -a unknown:16 means you don't know the algorithm, but at least you know it returns 16 bits
• Option -E hex means you want a hexadecimal encoding for the message digest
• Option -q hex:050000 means you want to calcualate the message digest from the hex input 050000 quickly
• Option -e d893 means an expected hash value of d893, expressed as hex
  

jacksum -a unknown:16 -q hex:050000 -E hex -e d893 

produces the following output:

Trying 13 algorithms with a width of 16 bits that are supported by Jacksum 3.0.0 ...

Trying 30 CRC algorithms with a width of 16 bits by testing against well known CRCs ...
crc:16,1021,FFFF,false,false,FFFF
    --> CRC-16/GENIBUS

Trying all CRC algorithms with a width of 16 bits by brute force (be patient!) ...
crc:16,1021,FFFF,false,false,FFFF
crc:16,37D2,FFFF,true,false,FFFF
crc:16,3E2D,0000,true,false,FFFF
crc:16,4175,FFFF,true,false,FFFF
crc:16,4A5B,FFFF,true,true,0000
crc:16,5A41,FFFF,true,false,FFFF
crc:16,5C63,FFFF,true,true,0000
crc:16,6287,FFFF,true,true,0000
crc:16,649C,0000,false,true,FFFF
crc:16,6D55,FFFF,true,true,0000
crc:16,75AC,FFFF,true,false,FFFF
crc:16,7D64,FFFF,false,false,FFFF
crc:16,81A6,FFFF,true,false,FFFF
crc:16,B9F9,FFFF,true,true,0000
crc:16,C3D6,FFFF,false,false,FFFF
crc:16,D436,0000,true,false,FFFF
crc:16,D6D2,0000,false,true,FFFF
crc:16,DA9C,FFFF,true,false,FFFF
crc:16,E03E,FFFF,false,false,FFFF
crc:16,F701,FFFF,true,false,FFFF


Jacksum: algorithms tested: 1048620
Jacksum: algorithms found: 21

Jacksum: elapsed time: 6 s, 460 ms

Means Jacksum has tested more than one million algorithms in about 7 seconds and it found 21 matching algorithms. Each of those returns the same CRC value. Test with more input/output sequences and/or longer input sequences in order to find the right algorithm. The most likely algorithm is printed with a name if it is a well known CRC. In this example it has been identified as the CRC-16/GENIBUS.

Once you have identified the correct algorithm, you can calculate your own input data using the CRC definitions that have been found:

jacksum -a crc:16,1021,FFFF,false,false,FFFF -E hex -q hex:050000
d893 3

The output "d893 3" means that 3 bytes have been read (050000) in order to produce the 16 bit (2 byte) hexadecimal value d893 using the algorithm as defined by -a.

Mission completed.

Cheers,
Johann

Jacksum 3 is on the web!

I am pleased to announce that Jacksum 3 has been released!

Jacksum 3 is a major release. I call it the "good things will take time" release ;-)

See also https://jacksum.net

Detailed release notes at https://jacksum.net/en/release-notes.html

Here is an eagle view comparison chart with Jacksum 1.7.0. There was never an official Jacksum 2 release and I lifted the version number immediately to 3 due to the feature richness of Jacksum 3.

 

	Jacksum 1.7.0	Jacksum 3.0.0
Algorithm support
Supported Algorithms (including different lengths)	58	470
Default algorithm	SHA-1	SHA-3-256
Full SHA-3 family support	no	yes
Full SHA-2 family support	no*1	yes
Full BLAKE-family support	no	almost*2
Full FNV-familiy support*3	no	yes
Customizable CRCs	yes	yes
Modern non-US modern national standards*4	no	yes
Older non-US national standards*5	yes	yes
All algos from round three of the NIST SHA-3 competition*6	no	yes
proposals from the NIST crypto workshops*7	no	yes
eXtendable Output Functions (XOF) as cryptographic hash functions*8	no	yes
Multi core/processor support
multiple algorithms calculation	yes*9	yes
multiple algorithms calculation simultanously	no	yes
parallel hash calculation for files	no	yes
multi processor support for checking files	no	yes
Other highlights
Finding an algorithm/CRC by knowing both data and hash	no	yes
Select algorithms that match a bit width or a search string	no	yes
producing the output in a format you want	yes	yes
checking an output produced by a foreign software using parser definitions	no	yes
License	GPLv2+	GPLv3+

 

*1 SHA-512/224, SHA-512/256 were missing, because those algos were introduced in March 2012.

*2 BLAKE-[224,384,256,512], BLAKE2s-[8..256/8], BLAKE2b-[8..512/8], and BLAKE3 are supported; BLAKE2sp and BLAKE2bp are not yet supported

*3 including FNV-0, FNV-1, and FNV-1a for all bit lengths [32,64,128,256,512,1024]

*4 Streebog-[256,512] (Russia, GOST R 34.11-2012); SM3 (China); Kupyna[256,384,512] (Ukraine, DSTU 7564:2014); LSH-256-[224,256], LSH-512-[224,256,384,512] (South Korea, KS X 3262)

*5 GOST, GOST Crypto-Pro (Russia, GOST R 34.11-94); HAS-160 (KISA, South Korea) 

 *6 all five candidates from round 3 the NIST SHA-3 competition were BLAKE, Groestl, JH, Keccak, and  Skein

 *7 before the SHA-3 competition they were proposals from the NIST crypto workshops called FORK-256, DHA-256, and VSH-1024

*8 SHAKE128, SHAKE256, KangarooTwelve, MarsupilamiFourteen

*9 while a file is read only once if multiple algorithms have been selected, the actual hash calculation occurred sequentially and not in parallel