Research implementation of iso 9797 algorithm 3 in C.
I first published this on one of my blogs in 2010.
http://devinvenable.blogspot.com/2010/01/iso-9797-algorithm-3.html
Last Friday I set out to implement ISO 9797 algorithm 3 using the OpenSSL library. I did not have the specification handy, so I decided to to the best I could with what I could find by way of examples on the net.
I came across a description of the algorithm in this 2005 thread (http://www.derkeiler.com/Newsgroups/sci.crypt/2005-02/0374.html). This was posted in a query by someone named Christian. He also posted his keys, data and the expected answer.
H0 = 0 stages 1 to n: Hj = Enc(K, Dj XOR H{j-1}) MAC = Enc(K, Dec(K', Hn))
Francois Grieu replied with, "This is very likely ISO/IEC 9797-1, using DES as the block cipher, padding method 2, MAC algorithm 3." He provided an answer by sharing sample code in "some near-extinct dialect".
set m0 72C29C2371CC9BDB #message set m1 65B779B8E8D37B29 set m2 ECC154AA56A8799F set m3 AE2F498F76ED92F2
set pd 8000000000000000 #padding
set iv 0000000000000000 #initialisation vector
set k0 7962D9ECE03D1ACD #key set k1 4C76089DCE131543
set xx {iv} # setup
for mj in {m0} {m1} {m2} {m3} {pd} # for each block including padding
set xx xor {xx} {mj} # chain
set xx des -k {k0} -c {xx} #encrypt
end
set xx des -k {k1} -d {xx} #decrypt
set xx des -k {k0} -c {xx} #encrypt
echo {xx} #show result
5F1448EEA8AD90A7
I've implemented the same in c for the purpose of research.