Exetools Idenitfying a cryptographic algorithm
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#1
07-15-2020, 16:14
 wassim_ Friend Join Date: Nov 2002 Posts: 100 Rept. Given: 1 Rept. Rcvd 1 Time in 1 Post Thanks Given: 14 Thanks Rcvd at 10 Times in 4 Posts
Idenitfying a cryptographic algorithm

I need help identifying this decryption algorithm, the argument "s" in the function d3 is the encrypted string.
If this is a known algorithm, I would like to get the algorithm to write the encrypted string "s" myslef.

Code:
```function d3(s)
{
var _loc4_ = s.substr(0,11);
var _loc9_ = Number(_loc4_.substr(10,1));
var _loc3_ = Number(_loc4_.substr(_loc9_,2));
var _loc7_ = s.substr(22,_loc3_);
var _loc10_ = String(s.substr(11,11));
var _loc8_ = Number(s.substr(21,1));
var _loc6_ = Number(s.substr(11 + _loc8_,2));
var _loc5_ = s.substr(22 + _loc3_,s.length - (22 + _loc3_));
return this.d(_loc7_,_loc6_,_loc5_);
}
function d(a, k, s)
{
return this.t(a,- k,s);
}
function t(a, k, s)
{
var _loc8_ = undefined;
var _loc3_ = "";
var _loc4_ = s.length;
var _loc2_ = 0;
while(_loc2_ < _loc4_)
{
_loc3_ = _loc3_ + this.r(a,s.charAt(_loc2_),k);
_loc2_ = _loc2_ + 1;
}
return _loc3_;
}
function r(a, c, k)
{
var _loc2_ = a.indexOf(c);
var _loc1_ = a.length;
if(_loc2_ != -1)
{
return a.charAt((_loc2_ + k + _loc1_) % _loc1_);
}
return c;
}```
#2
07-15-2020, 22:15
 chants Family Join Date: Jul 2016 Posts: 559 Rept. Given: 6 Rept. Rcvd 35 Times in 21 Posts Thanks Given: 472 Thanks Rcvd at 835 Times in 392 Posts
I think if you rewrote and cleaned up that code, it would be easier. It appears not as a much of a cryptographic algorithm as some simple string manipulation code. It can be a single function with a loop having a single condition inside of it. After cleaning it up, figuring out how to invert the function should be somewhat straight forward.
 The Following User Says Thank You to chants For This Useful Post: niculaita (07-16-2020)

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