i have a .dat file. how do i go about decryting it and what tool or tutorial that i need to read. been reading everywhere but to no avail....

You'll need to do RDE (Reverse Data Engineering) instead of RCE then... or if you have the program which manipulates the .dat file you said, then you could reverse that program to figure it out.

im still searching the crack archive for a very good crypto tutorial and type of soft that use the same method or more or less....

but here a low down on the security spec, (it is the weirdess of security, but im sure u guys can do it within half an hour.)

it uses a so called dongle for the the full version of the software. the software check with "daemon" wherether it is connected or not. after that is full fledge.
"daemon" installed is the actual one that check for the dongle. virtually wiping out the patch for the Software. Now we only need to patch the "daemon" to make it stay connected forever. And here comes the second part, the Registration key file. There are two file both *.dat file but one is encryted and the other is not. Both hold the Reg name inside of it, so you cant go changing one and expect it to work. (Tried it but softwares auto exit on error of reg, stating the reg name on one is not the same in the other, which is the encrypted one.)

ok here come the best part, i manage to find the demo key file in a zip file in the cd given but to only god knows why it is password lock, but the inside of the was a gold mine, it has all the other demo key file for the other softwares that was offered. I manage to crack the password with plaintext, i found one of the unencryted demo key file which was there in the cd and which is exactly the same in the zip and bada bing bada boom! your password is....

So ran the new key file which was the demo ( here we must make note that the both key file must be present during the installation, and that is unencrypt.dat and encrypt.dat, the unencrypt.dat is always the same but the encrypt.dat have different file name for each type of app) and the app started without the need of the dongle.(very curious????). switch both the key file, and what do you know... the app hangs because the dongle was not present.(the unencrypt.dat file is the same, only difference is the the reg name, i know since i can see it, and since i mention earlier it check if both are the same reg name)

This made me come to one conclusion that the security and type of app that can run is depending the encrypted key file. so that is why im here.......

by the way between the full key file and the demo key file. the full key file is about 640+ bytes and the demo is about 540+ bytes.